chore: vendor go dependencies

23 files changed, 2020 insertions, 0 deletions

diff --git a/vendor/github.com/opencontainers/go-digest/.mailmap b/vendor/github.com/opencontainers/go-digest/.mailmap
new file mode 100644
index 0000000..eaf8b2f
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/.mailmap
@@ -0,0 +1,4 @@
+Aaron Lehmann <aaronl@vitelus.com> <aaron.lehmann@docker.com>
+Derek McGowan <derek@mcg.dev> <derek@mcgstyle.net>
+Stephen J Day <stephen.day@docker.com> <stevvooe@users.noreply.github.com>
+Haibing Zhou <zhouhaibing089@gmail.com>
diff --git a/vendor/github.com/opencontainers/go-digest/.pullapprove.yml b/vendor/github.com/opencontainers/go-digest/.pullapprove.yml
new file mode 100644
index 0000000..b6165f8
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/.pullapprove.yml
@@ -0,0 +1,28 @@
+version: 2
+
+requirements:
+  signed_off_by:
+    required: true
+
+always_pending:
+  title_regex: '^WIP'
+  explanation: 'Work in progress...'
+
+group_defaults:
+  required: 2
+  approve_by_comment:
+    enabled: true
+    approve_regex: '^LGTM'
+    reject_regex: '^Rejected'
+  reset_on_push:
+    enabled: true
+  author_approval:
+    ignored: true
+  conditions:
+    branches:
+      - master
+
+groups:
+  go-digest:
+    teams:
+      - go-digest-maintainers
diff --git a/vendor/github.com/opencontainers/go-digest/.travis.yml b/vendor/github.com/opencontainers/go-digest/.travis.yml
new file mode 100644
index 0000000..5775f88
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/.travis.yml
@@ -0,0 +1,5 @@
+language: go
+go:
+  - 1.12.x
+  - 1.13.x
+  - master
diff --git a/vendor/github.com/opencontainers/go-digest/CONTRIBUTING.md b/vendor/github.com/opencontainers/go-digest/CONTRIBUTING.md
new file mode 100644
index 0000000..e4d962a
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/CONTRIBUTING.md
@@ -0,0 +1,72 @@
+# Contributing to Docker open source projects
+
+Want to hack on this project? Awesome! Here are instructions to get you started.
+
+This project is a part of the [Docker](https://www.docker.com) project, and follows
+the same rules and principles. If you're already familiar with the way
+Docker does things, you'll feel right at home.
+
+Otherwise, go read Docker's
+[contributions guidelines](https://github.com/docker/docker/blob/master/CONTRIBUTING.md),
+[issue triaging](https://github.com/docker/docker/blob/master/project/ISSUE-TRIAGE.md),
+[review process](https://github.com/docker/docker/blob/master/project/REVIEWING.md) and
+[branches and tags](https://github.com/docker/docker/blob/master/project/BRANCHES-AND-TAGS.md).
+
+For an in-depth description of our contribution process, visit the
+contributors guide: [Understand how to contribute](https://docs.docker.com/opensource/workflow/make-a-contribution/)
+
+### Sign your work
+
+The sign-off is a simple line at the end of the explanation for the patch. Your
+signature certifies that you wrote the patch or otherwise have the right to pass
+it on as an open-source patch. The rules are pretty simple: if you can certify
+the below (from [developercertificate.org](http://developercertificate.org/)):
+
+```
+Developer Certificate of Origin
+Version 1.1
+
+Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
+1 Letterman Drive
+Suite D4700
+San Francisco, CA, 94129
+
+Everyone is permitted to copy and distribute verbatim copies of this
+license document, but changing it is not allowed.
+
+
+Developer's Certificate of Origin 1.1
+
+By making a contribution to this project, I certify that:
+
+(a) The contribution was created in whole or in part by me and I
+    have the right to submit it under the open source license
+    indicated in the file; or
+
+(b) The contribution is based upon previous work that, to the best
+    of my knowledge, is covered under an appropriate open source
+    license and I have the right under that license to submit that
+    work with modifications, whether created in whole or in part
+    by me, under the same open source license (unless I am
+    permitted to submit under a different license), as indicated
+    in the file; or
+
+(c) The contribution was provided directly to me by some other
+    person who certified (a), (b) or (c) and I have not modified
+    it.
+
+(d) I understand and agree that this project and the contribution
+    are public and that a record of the contribution (including all
+    personal information I submit with it, including my sign-off) is
+    maintained indefinitely and may be redistributed consistent with
+    this project or the open source license(s) involved.
+```
+
+Then you just add a line to every git commit message:
+
+    Signed-off-by: Joe Smith <joe.smith@email.com>
+
+Use your real name (sorry, no pseudonyms or anonymous contributions.)
+
+If you set your `user.name` and `user.email` git configs, you can sign your
+commit automatically with `git commit -s`.
diff --git a/vendor/github.com/opencontainers/go-digest/LICENSE b/vendor/github.com/opencontainers/go-digest/LICENSE
new file mode 100644
index 0000000..3ac8ab6
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/LICENSE
@@ -0,0 +1,192 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        https://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   Copyright 2019, 2020 OCI Contributors
+   Copyright 2016 Docker, Inc.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       https://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
diff --git a/vendor/github.com/opencontainers/go-digest/LICENSE.docs b/vendor/github.com/opencontainers/go-digest/LICENSE.docs
new file mode 100644
index 0000000..e26cd4f
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/LICENSE.docs
@@ -0,0 +1,425 @@
+Attribution-ShareAlike 4.0 International
+
+=======================================================================
+
+Creative Commons Corporation ("Creative Commons") is not a law firm and
+does not provide legal services or legal advice. Distribution of
+Creative Commons public licenses does not create a lawyer-client or
+other relationship. Creative Commons makes its licenses and related
+information available on an "as-is" basis. Creative Commons gives no
+warranties regarding its licenses, any material licensed under their
+terms and conditions, or any related information. Creative Commons
+disclaims all liability for damages resulting from their use to the
+fullest extent possible.
+
+Using Creative Commons Public Licenses
+
+Creative Commons public licenses provide a standard set of terms and
+conditions that creators and other rights holders may use to share
+original works of authorship and other material subject to copyright
+and certain other rights specified in the public license below. The
+following considerations are for informational purposes only, are not
+exhaustive, and do not form part of our licenses.
+
+     Considerations for licensors: Our public licenses are
+     intended for use by those authorized to give the public
+     permission to use material in ways otherwise restricted by
+     copyright and certain other rights. Our licenses are
+     irrevocable. Licensors should read and understand the terms
+     and conditions of the license they choose before applying it.
+     Licensors should also secure all rights necessary before
+     applying our licenses so that the public can reuse the
+     material as expected. Licensors should clearly mark any
+     material not subject to the license. This includes other CC-
+     licensed material, or material used under an exception or
+     limitation to copyright. More considerations for licensors:
+	wiki.creativecommons.org/Considerations_for_licensors
+
+     Considerations for the public: By using one of our public
+     licenses, a licensor grants the public permission to use the
+     licensed material under specified terms and conditions. If
+     the licensor's permission is not necessary for any reason--for
+     example, because of any applicable exception or limitation to
+     copyright--then that use is not regulated by the license. Our
+     licenses grant only permissions under copyright and certain
+     other rights that a licensor has authority to grant. Use of
+     the licensed material may still be restricted for other
+     reasons, including because others have copyright or other
+     rights in the material. A licensor may make special requests,
+     such as asking that all changes be marked or described.
+     Although not required by our licenses, you are encouraged to
+     respect those requests where reasonable. More_considerations
+     for the public:
+	wiki.creativecommons.org/Considerations_for_licensees
+
+=======================================================================
+
+Creative Commons Attribution-ShareAlike 4.0 International Public
+License
+
+By exercising the Licensed Rights (defined below), You accept and agree
+to be bound by the terms and conditions of this Creative Commons
+Attribution-ShareAlike 4.0 International Public License ("Public
+License"). To the extent this Public License may be interpreted as a
+contract, You are granted the Licensed Rights in consideration of Your
+acceptance of these terms and conditions, and the Licensor grants You
+such rights in consideration of benefits the Licensor receives from
+making the Licensed Material available under these terms and
+conditions.
+
+
+Section 1 -- Definitions.
+
+  a. Adapted Material means material subject to Copyright and Similar
+     Rights that is derived from or based upon the Licensed Material
+     and in which the Licensed Material is translated, altered,
+     arranged, transformed, or otherwise modified in a manner requiring
+     permission under the Copyright and Similar Rights held by the
+     Licensor. For purposes of this Public License, where the Licensed
+     Material is a musical work, performance, or sound recording,
+     Adapted Material is always produced where the Licensed Material is
+     synched in timed relation with a moving image.
+
+  b. Adapter's License means the license You apply to Your Copyright
+     and Similar Rights in Your contributions to Adapted Material in
+     accordance with the terms and conditions of this Public License.
+
+  c. BY-SA Compatible License means a license listed at
+     creativecommons.org/compatiblelicenses, approved by Creative
+     Commons as essentially the equivalent of this Public License.
+
+  d. Copyright and Similar Rights means copyright and/or similar rights
+     closely related to copyright including, without limitation,
+     performance, broadcast, sound recording, and Sui Generis Database
+     Rights, without regard to how the rights are labeled or
+     categorized. For purposes of this Public License, the rights
+     specified in Section 2(b)(1)-(2) are not Copyright and Similar
+     Rights.
+
+  e. Effective Technological Measures means those measures that, in the
+     absence of proper authority, may not be circumvented under laws
+     fulfilling obligations under Article 11 of the WIPO Copyright
+     Treaty adopted on December 20, 1996, and/or similar international
+     agreements.
+
+  f. Exceptions and Limitations means fair use, fair dealing, and/or
+     any other exception or limitation to Copyright and Similar Rights
+     that applies to Your use of the Licensed Material.
+
+  g. License Elements means the license attributes listed in the name
+     of a Creative Commons Public License. The License Elements of this
+     Public License are Attribution and ShareAlike.
+
+  h. Licensed Material means the artistic or literary work, database,
+     or other material to which the Licensor applied this Public
+     License.
+
+  i. Licensed Rights means the rights granted to You subject to the
+     terms and conditions of this Public License, which are limited to
+     all Copyright and Similar Rights that apply to Your use of the
+     Licensed Material and that the Licensor has authority to license.
+
+  j. Licensor means the individual(s) or entity(ies) granting rights
+     under this Public License.
+
+  k. Share means to provide material to the public by any means or
+     process that requires permission under the Licensed Rights, such
+     as reproduction, public display, public performance, distribution,
+     dissemination, communication, or importation, and to make material
+     available to the public including in ways that members of the
+     public may access the material from a place and at a time
+     individually chosen by them.
+
+  l. Sui Generis Database Rights means rights other than copyright
+     resulting from Directive 96/9/EC of the European Parliament and of
+     the Council of 11 March 1996 on the legal protection of databases,
+     as amended and/or succeeded, as well as other essentially
+     equivalent rights anywhere in the world.
+
+  m. You means the individual or entity exercising the Licensed Rights
+     under this Public License. Your has a corresponding meaning.
+
+
+Section 2 -- Scope.
+
+  a. License grant.
+
+       1. Subject to the terms and conditions of this Public License,
+          the Licensor hereby grants You a worldwide, royalty-free,
+          non-sublicensable, non-exclusive, irrevocable license to
+          exercise the Licensed Rights in the Licensed Material to:
+
+            a. reproduce and Share the Licensed Material, in whole or
+               in part; and
+
+            b. produce, reproduce, and Share Adapted Material.
+
+       2. Exceptions and Limitations. For the avoidance of doubt, where
+          Exceptions and Limitations apply to Your use, this Public
+          License does not apply, and You do not need to comply with
+          its terms and conditions.
+
+       3. Term. The term of this Public License is specified in Section
+          6(a).
+
+       4. Media and formats; technical modifications allowed. The
+          Licensor authorizes You to exercise the Licensed Rights in
+          all media and formats whether now known or hereafter created,
+          and to make technical modifications necessary to do so. The
+          Licensor waives and/or agrees not to assert any right or
+          authority to forbid You from making technical modifications
+          necessary to exercise the Licensed Rights, including
+          technical modifications necessary to circumvent Effective
+          Technological Measures. For purposes of this Public License,
+          simply making modifications authorized by this Section 2(a)
+          (4) never produces Adapted Material.
+
+       5. Downstream recipients.
+
+            a. Offer from the Licensor -- Licensed Material. Every
+               recipient of the Licensed Material automatically
+               receives an offer from the Licensor to exercise the
+               Licensed Rights under the terms and conditions of this
+               Public License.
+
+            b. Additional offer from the Licensor -- Adapted Material.
+               Every recipient of Adapted Material from You
+               automatically receives an offer from the Licensor to
+               exercise the Licensed Rights in the Adapted Material
+               under the conditions of the Adapter's License You apply.
+
+            c. No downstream restrictions. You may not offer or impose
+               any additional or different terms or conditions on, or
+               apply any Effective Technological Measures to, the
+               Licensed Material if doing so restricts exercise of the
+               Licensed Rights by any recipient of the Licensed
+               Material.
+
+       6. No endorsement. Nothing in this Public License constitutes or
+          may be construed as permission to assert or imply that You
+          are, or that Your use of the Licensed Material is, connected
+          with, or sponsored, endorsed, or granted official status by,
+          the Licensor or others designated to receive attribution as
+          provided in Section 3(a)(1)(A)(i).
+
+  b. Other rights.
+
+       1. Moral rights, such as the right of integrity, are not
+          licensed under this Public License, nor are publicity,
+          privacy, and/or other similar personality rights; however, to
+          the extent possible, the Licensor waives and/or agrees not to
+          assert any such rights held by the Licensor to the limited
+          extent necessary to allow You to exercise the Licensed
+          Rights, but not otherwise.
+
+       2. Patent and trademark rights are not licensed under this
+          Public License.
+
+       3. To the extent possible, the Licensor waives any right to
+          collect royalties from You for the exercise of the Licensed
+          Rights, whether directly or through a collecting society
+          under any voluntary or waivable statutory or compulsory
+          licensing scheme. In all other cases the Licensor expressly
+          reserves any right to collect such royalties.
+
+
+Section 3 -- License Conditions.
+
+Your exercise of the Licensed Rights is expressly made subject to the
+following conditions.
+
+  a. Attribution.
+
+       1. If You Share the Licensed Material (including in modified
+          form), You must:
+
+            a. retain the following if it is supplied by the Licensor
+               with the Licensed Material:
+
+                 i. identification of the creator(s) of the Licensed
+                    Material and any others designated to receive
+                    attribution, in any reasonable manner requested by
+                    the Licensor (including by pseudonym if
+                    designated);
+
+                ii. a copyright notice;
+
+               iii. a notice that refers to this Public License;
+
+                iv. a notice that refers to the disclaimer of
+                    warranties;
+
+                 v. a URI or hyperlink to the Licensed Material to the
+                    extent reasonably practicable;
+
+            b. indicate if You modified the Licensed Material and
+               retain an indication of any previous modifications; and
+
+            c. indicate the Licensed Material is licensed under this
+               Public License, and include the text of, or the URI or
+               hyperlink to, this Public License.
+
+       2. You may satisfy the conditions in Section 3(a)(1) in any
+          reasonable manner based on the medium, means, and context in
+          which You Share the Licensed Material. For example, it may be
+          reasonable to satisfy the conditions by providing a URI or
+          hyperlink to a resource that includes the required
+          information.
+
+       3. If requested by the Licensor, You must remove any of the
+          information required by Section 3(a)(1)(A) to the extent
+          reasonably practicable.
+
+  b. ShareAlike.
+
+     In addition to the conditions in Section 3(a), if You Share
+     Adapted Material You produce, the following conditions also apply.
+
+       1. The Adapter's License You apply must be a Creative Commons
+          license with the same License Elements, this version or
+          later, or a BY-SA Compatible License.
+
+       2. You must include the text of, or the URI or hyperlink to, the
+          Adapter's License You apply. You may satisfy this condition
+          in any reasonable manner based on the medium, means, and
+          context in which You Share Adapted Material.
+
+       3. You may not offer or impose any additional or different terms
+          or conditions on, or apply any Effective Technological
+          Measures to, Adapted Material that restrict exercise of the
+          rights granted under the Adapter's License You apply.
+
+
+Section 4 -- Sui Generis Database Rights.
+
+Where the Licensed Rights include Sui Generis Database Rights that
+apply to Your use of the Licensed Material:
+
+  a. for the avoidance of doubt, Section 2(a)(1) grants You the right
+     to extract, reuse, reproduce, and Share all or a substantial
+     portion of the contents of the database;
+
+  b. if You include all or a substantial portion of the database
+     contents in a database in which You have Sui Generis Database
+     Rights, then the database in which You have Sui Generis Database
+     Rights (but not its individual contents) is Adapted Material,
+
+     including for purposes of Section 3(b); and
+  c. You must comply with the conditions in Section 3(a) if You Share
+     all or a substantial portion of the contents of the database.
+
+For the avoidance of doubt, this Section 4 supplements and does not
+replace Your obligations under this Public License where the Licensed
+Rights include other Copyright and Similar Rights.
+
+
+Section 5 -- Disclaimer of Warranties and Limitation of Liability.
+
+  a. UNLESS OTHERWISE SEPARATELY UNDERTAKEN BY THE LICENSOR, TO THE
+     EXTENT POSSIBLE, THE LICENSOR OFFERS THE LICENSED MATERIAL AS-IS
+     AND AS-AVAILABLE, AND MAKES NO REPRESENTATIONS OR WARRANTIES OF
+     ANY KIND CONCERNING THE LICENSED MATERIAL, WHETHER EXPRESS,
+     IMPLIED, STATUTORY, OR OTHER. THIS INCLUDES, WITHOUT LIMITATION,
+     WARRANTIES OF TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR
+     PURPOSE, NON-INFRINGEMENT, ABSENCE OF LATENT OR OTHER DEFECTS,
+     ACCURACY, OR THE PRESENCE OR ABSENCE OF ERRORS, WHETHER OR NOT
+     KNOWN OR DISCOVERABLE. WHERE DISCLAIMERS OF WARRANTIES ARE NOT
+     ALLOWED IN FULL OR IN PART, THIS DISCLAIMER MAY NOT APPLY TO YOU.
+
+  b. TO THE EXTENT POSSIBLE, IN NO EVENT WILL THE LICENSOR BE LIABLE
+     TO YOU ON ANY LEGAL THEORY (INCLUDING, WITHOUT LIMITATION,
+     NEGLIGENCE) OR OTHERWISE FOR ANY DIRECT, SPECIAL, INDIRECT,
+     INCIDENTAL, CONSEQUENTIAL, PUNITIVE, EXEMPLARY, OR OTHER LOSSES,
+     COSTS, EXPENSES, OR DAMAGES ARISING OUT OF THIS PUBLIC LICENSE OR
+     USE OF THE LICENSED MATERIAL, EVEN IF THE LICENSOR HAS BEEN
+     ADVISED OF THE POSSIBILITY OF SUCH LOSSES, COSTS, EXPENSES, OR
+     DAMAGES. WHERE A LIMITATION OF LIABILITY IS NOT ALLOWED IN FULL OR
+     IN PART, THIS LIMITATION MAY NOT APPLY TO YOU.
+
+  c. The disclaimer of warranties and limitation of liability provided
+     above shall be interpreted in a manner that, to the extent
+     possible, most closely approximates an absolute disclaimer and
+     waiver of all liability.
+
+
+Section 6 -- Term and Termination.
+
+  a. This Public License applies for the term of the Copyright and
+     Similar Rights licensed here. However, if You fail to comply with
+     this Public License, then Your rights under this Public License
+     terminate automatically.
+
+  b. Where Your right to use the Licensed Material has terminated under
+     Section 6(a), it reinstates:
+
+       1. automatically as of the date the violation is cured, provided
+          it is cured within 30 days of Your discovery of the
+          violation; or
+
+       2. upon express reinstatement by the Licensor.
+
+     For the avoidance of doubt, this Section 6(b) does not affect any
+     right the Licensor may have to seek remedies for Your violations
+     of this Public License.
+
+  c. For the avoidance of doubt, the Licensor may also offer the
+     Licensed Material under separate terms or conditions or stop
+     distributing the Licensed Material at any time; however, doing so
+     will not terminate this Public License.
+
+  d. Sections 1, 5, 6, 7, and 8 survive termination of this Public
+     License.
+
+
+Section 7 -- Other Terms and Conditions.
+
+  a. The Licensor shall not be bound by any additional or different
+     terms or conditions communicated by You unless expressly agreed.
+
+  b. Any arrangements, understandings, or agreements regarding the
+     Licensed Material not stated herein are separate from and
+     independent of the terms and conditions of this Public License.
+
+
+Section 8 -- Interpretation.
+
+  a. For the avoidance of doubt, this Public License does not, and
+     shall not be interpreted to, reduce, limit, restrict, or impose
+     conditions on any use of the Licensed Material that could lawfully
+     be made without permission under this Public License.
+
+  b. To the extent possible, if any provision of this Public License is
+     deemed unenforceable, it shall be automatically reformed to the
+     minimum extent necessary to make it enforceable. If the provision
+     cannot be reformed, it shall be severed from this Public License
+     without affecting the enforceability of the remaining terms and
+     conditions.
+
+  c. No term or condition of this Public License will be waived and no
+     failure to comply consented to unless expressly agreed to by the
+     Licensor.
+
+  d. Nothing in this Public License constitutes or may be interpreted
+     as a limitation upon, or waiver of, any privileges and immunities
+     that apply to the Licensor or You, including from the legal
+     processes of any jurisdiction or authority.
+
+
+=======================================================================
+
+Creative Commons is not a party to its public licenses.
+Notwithstanding, Creative Commons may elect to apply one of its public
+licenses to material it publishes and in those instances will be
+considered the "Licensor." Except for the limited purpose of indicating
+that material is shared under a Creative Commons public license or as
+otherwise permitted by the Creative Commons policies published at
+creativecommons.org/policies, Creative Commons does not authorize the
+use of the trademark "Creative Commons" or any other trademark or logo
+of Creative Commons without its prior written consent including,
+without limitation, in connection with any unauthorized modifications
+to any of its public licenses or any other arrangements,
+understandings, or agreements concerning use of licensed material. For
+the avoidance of doubt, this paragraph does not form part of the public
+licenses.
+
+Creative Commons may be contacted at creativecommons.org.
diff --git a/vendor/github.com/opencontainers/go-digest/MAINTAINERS b/vendor/github.com/opencontainers/go-digest/MAINTAINERS
new file mode 100644
index 0000000..843b1b2
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/MAINTAINERS
@@ -0,0 +1,5 @@
+Derek McGowan <derek@mcgstyle.net> (@dmcgowan)
+Stephen Day <stevvooe@gmail.com> (@stevvooe)
+Vincent Batts <vbatts@hashbangbash.com> (@vbatts)
+Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp> (@AkihiroSuda)
+Sebastiaan van Stijn <github@gone.nl> (@thaJeztah)
diff --git a/vendor/github.com/opencontainers/go-digest/README.md b/vendor/github.com/opencontainers/go-digest/README.md
new file mode 100644
index 0000000..a112872
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/README.md
@@ -0,0 +1,96 @@
+# go-digest
+
+[![GoDoc](https://godoc.org/github.com/opencontainers/go-digest?status.svg)](https://godoc.org/github.com/opencontainers/go-digest) [![Go Report Card](https://goreportcard.com/badge/github.com/opencontainers/go-digest)](https://goreportcard.com/report/github.com/opencontainers/go-digest) [![Build Status](https://travis-ci.org/opencontainers/go-digest.svg?branch=master)](https://travis-ci.org/opencontainers/go-digest)
+
+Common digest package used across the container ecosystem.
+
+Please see the [godoc](https://godoc.org/github.com/opencontainers/go-digest) for more information.
+
+# What is a digest?
+
+A digest is just a [hash](https://en.wikipedia.org/wiki/Hash_function).
+
+The most common use case for a digest is to create a content identifier for use in [Content Addressable Storage](https://en.wikipedia.org/wiki/Content-addressable_storage) systems:
+
+```go
+id := digest.FromBytes([]byte("my content"))
+```
+
+In the example above, the id can be used to uniquely identify the byte slice "my content".
+This allows two disparate applications to agree on a verifiable identifier without having to trust one another.
+
+An identifying digest can be verified, as follows:
+
+```go
+if id != digest.FromBytes([]byte("my content")) {
+  return errors.New("the content has changed!")
+}
+```
+
+A `Verifier` type can be used to handle cases where an `io.Reader` makes more sense:
+
+```go
+rd := getContent()
+verifier := id.Verifier()
+io.Copy(verifier, rd)
+
+if !verifier.Verified() {
+  return errors.New("the content has changed!")
+}
+```
+
+Using [Merkle DAGs](https://en.wikipedia.org/wiki/Merkle_tree), this can power a rich, safe, content distribution system.
+
+# Usage
+
+While the [godoc](https://godoc.org/github.com/opencontainers/go-digest) is considered the best resource, a few important items need to be called out when using this package.
+
+1. Make sure to import the hash implementations into your application or the package will panic.
+    You should have something like the following in the main (or other entrypoint) of your application:
+   
+    ```go
+    import (
+        _ "crypto/sha256"
+        _ "crypto/sha512"
+    )
+    ```
+    This may seem inconvenient but it allows you replace the hash 
+    implementations with others, such as https://github.com/stevvooe/resumable.
+ 
+2. Even though `digest.Digest` may be assemblable as a string, _always_ verify your input with `digest.Parse` or use `Digest.Validate` when accepting untrusted input.
+    While there are measures to avoid common problems, this will ensure you have valid digests in the rest of your application.
+
+3. While alternative encodings of hash values (digests) are possible (for example, base64), this package deals exclusively with hex-encoded digests.
+
+# Stability
+
+The Go API, at this stage, is considered stable, unless otherwise noted.
+
+As always, before using a package export, read the [godoc](https://godoc.org/github.com/opencontainers/go-digest).
+
+# Contributing
+
+This package is considered fairly complete.
+It has been in production in thousands (millions?) of deployments and is fairly battle-hardened.
+New additions will be met with skepticism.
+If you think there is a missing feature, please file a bug clearly describing the problem and the alternatives you tried before submitting a PR.
+
+## Code of Conduct
+
+Participation in the OpenContainers community is governed by [OpenContainer's Code of Conduct][code-of-conduct].
+
+## Security
+
+If you find an issue, please follow the [security][security] protocol to report it.
+
+# Copyright and license
+
+Copyright © 2019, 2020 OCI Contributors
+Copyright © 2016 Docker, Inc.
+All rights reserved, except as follows.
+Code is released under the [Apache 2.0 license](LICENSE).
+This `README.md` file and the [`CONTRIBUTING.md`](CONTRIBUTING.md) file are licensed under the Creative Commons Attribution 4.0 International License under the terms and conditions set forth in the file [`LICENSE.docs`](LICENSE.docs).
+You may obtain a duplicate copy of the same license, titled CC BY-SA 4.0, at http://creativecommons.org/licenses/by-sa/4.0/.
+
+[security]: https://github.com/opencontainers/org/blob/master/security
+[code-of-conduct]: https://github.com/opencontainers/org/blob/master/CODE_OF_CONDUCT.md
diff --git a/vendor/github.com/opencontainers/go-digest/algorithm.go b/vendor/github.com/opencontainers/go-digest/algorithm.go
new file mode 100644
index 0000000..490951d
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/algorithm.go
@@ -0,0 +1,193 @@
+// Copyright 2019, 2020 OCI Contributors
+// Copyright 2017 Docker, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package digest
+
+import (
+	"crypto"
+	"fmt"
+	"hash"
+	"io"
+	"regexp"
+)
+
+// Algorithm identifies and implementation of a digester by an identifier.
+// Note the that this defines both the hash algorithm used and the string
+// encoding.
+type Algorithm string
+
+// supported digest types
+const (
+	SHA256 Algorithm = "sha256" // sha256 with hex encoding (lower case only)
+	SHA384 Algorithm = "sha384" // sha384 with hex encoding (lower case only)
+	SHA512 Algorithm = "sha512" // sha512 with hex encoding (lower case only)
+
+	// Canonical is the primary digest algorithm used with the distribution
+	// project. Other digests may be used but this one is the primary storage
+	// digest.
+	Canonical = SHA256
+)
+
+var (
+	// TODO(stevvooe): Follow the pattern of the standard crypto package for
+	// registration of digests. Effectively, we are a registerable set and
+	// common symbol access.
+
+	// algorithms maps values to hash.Hash implementations. Other algorithms
+	// may be available but they cannot be calculated by the digest package.
+	algorithms = map[Algorithm]crypto.Hash{
+		SHA256: crypto.SHA256,
+		SHA384: crypto.SHA384,
+		SHA512: crypto.SHA512,
+	}
+
+	// anchoredEncodedRegexps contains anchored regular expressions for hex-encoded digests.
+	// Note that /A-F/ disallowed.
+	anchoredEncodedRegexps = map[Algorithm]*regexp.Regexp{
+		SHA256: regexp.MustCompile(`^[a-f0-9]{64}$`),
+		SHA384: regexp.MustCompile(`^[a-f0-9]{96}$`),
+		SHA512: regexp.MustCompile(`^[a-f0-9]{128}$`),
+	}
+)
+
+// Available returns true if the digest type is available for use. If this
+// returns false, Digester and Hash will return nil.
+func (a Algorithm) Available() bool {
+	h, ok := algorithms[a]
+	if !ok {
+		return false
+	}
+
+	// check availability of the hash, as well
+	return h.Available()
+}
+
+func (a Algorithm) String() string {
+	return string(a)
+}
+
+// Size returns number of bytes returned by the hash.
+func (a Algorithm) Size() int {
+	h, ok := algorithms[a]
+	if !ok {
+		return 0
+	}
+	return h.Size()
+}
+
+// Set implemented to allow use of Algorithm as a command line flag.
+func (a *Algorithm) Set(value string) error {
+	if value == "" {
+		*a = Canonical
+	} else {
+		// just do a type conversion, support is queried with Available.
+		*a = Algorithm(value)
+	}
+
+	if !a.Available() {
+		return ErrDigestUnsupported
+	}
+
+	return nil
+}
+
+// Digester returns a new digester for the specified algorithm. If the algorithm
+// does not have a digester implementation, nil will be returned. This can be
+// checked by calling Available before calling Digester.
+func (a Algorithm) Digester() Digester {
+	return &digester{
+		alg:  a,
+		hash: a.Hash(),
+	}
+}
+
+// Hash returns a new hash as used by the algorithm. If not available, the
+// method will panic. Check Algorithm.Available() before calling.
+func (a Algorithm) Hash() hash.Hash {
+	if !a.Available() {
+		// Empty algorithm string is invalid
+		if a == "" {
+			panic(fmt.Sprintf("empty digest algorithm, validate before calling Algorithm.Hash()"))
+		}
+
+		// NOTE(stevvooe): A missing hash is usually a programming error that
+		// must be resolved at compile time. We don't import in the digest
+		// package to allow users to choose their hash implementation (such as
+		// when using stevvooe/resumable or a hardware accelerated package).
+		//
+		// Applications that may want to resolve the hash at runtime should
+		// call Algorithm.Available before call Algorithm.Hash().
+		panic(fmt.Sprintf("%v not available (make sure it is imported)", a))
+	}
+
+	return algorithms[a].New()
+}
+
+// Encode encodes the raw bytes of a digest, typically from a hash.Hash, into
+// the encoded portion of the digest.
+func (a Algorithm) Encode(d []byte) string {
+	// TODO(stevvooe): Currently, all algorithms use a hex encoding. When we
+	// add support for back registration, we can modify this accordingly.
+	return fmt.Sprintf("%x", d)
+}
+
+// FromReader returns the digest of the reader using the algorithm.
+func (a Algorithm) FromReader(rd io.Reader) (Digest, error) {
+	digester := a.Digester()
+
+	if _, err := io.Copy(digester.Hash(), rd); err != nil {
+		return "", err
+	}
+
+	return digester.Digest(), nil
+}
+
+// FromBytes digests the input and returns a Digest.
+func (a Algorithm) FromBytes(p []byte) Digest {
+	digester := a.Digester()
+
+	if _, err := digester.Hash().Write(p); err != nil {
+		// Writes to a Hash should never fail. None of the existing
+		// hash implementations in the stdlib or hashes vendored
+		// here can return errors from Write. Having a panic in this
+		// condition instead of having FromBytes return an error value
+		// avoids unnecessary error handling paths in all callers.
+		panic("write to hash function returned error: " + err.Error())
+	}
+
+	return digester.Digest()
+}
+
+// FromString digests the string input and returns a Digest.
+func (a Algorithm) FromString(s string) Digest {
+	return a.FromBytes([]byte(s))
+}
+
+// Validate validates the encoded portion string
+func (a Algorithm) Validate(encoded string) error {
+	r, ok := anchoredEncodedRegexps[a]
+	if !ok {
+		return ErrDigestUnsupported
+	}
+	// Digests much always be hex-encoded, ensuring that their hex portion will
+	// always be size*2
+	if a.Size()*2 != len(encoded) {
+		return ErrDigestInvalidLength
+	}
+	if r.MatchString(encoded) {
+		return nil
+	}
+	return ErrDigestInvalidFormat
+}
diff --git a/vendor/github.com/opencontainers/go-digest/digest.go b/vendor/github.com/opencontainers/go-digest/digest.go
new file mode 100644
index 0000000..518b5e7
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/digest.go
@@ -0,0 +1,157 @@
+// Copyright 2019, 2020 OCI Contributors
+// Copyright 2017 Docker, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package digest
+
+import (
+	"fmt"
+	"hash"
+	"io"
+	"regexp"
+	"strings"
+)
+
+// Digest allows simple protection of hex formatted digest strings, prefixed
+// by their algorithm. Strings of type Digest have some guarantee of being in
+// the correct format and it provides quick access to the components of a
+// digest string.
+//
+// The following is an example of the contents of Digest types:
+//
+// 	sha256:7173b809ca12ec5dee4506cd86be934c4596dd234ee82c0662eac04a8c2c71dc
+//
+// This allows to abstract the digest behind this type and work only in those
+// terms.
+type Digest string
+
+// NewDigest returns a Digest from alg and a hash.Hash object.
+func NewDigest(alg Algorithm, h hash.Hash) Digest {
+	return NewDigestFromBytes(alg, h.Sum(nil))
+}
+
+// NewDigestFromBytes returns a new digest from the byte contents of p.
+// Typically, this can come from hash.Hash.Sum(...) or xxx.SumXXX(...)
+// functions. This is also useful for rebuilding digests from binary
+// serializations.
+func NewDigestFromBytes(alg Algorithm, p []byte) Digest {
+	return NewDigestFromEncoded(alg, alg.Encode(p))
+}
+
+// NewDigestFromHex is deprecated. Please use NewDigestFromEncoded.
+func NewDigestFromHex(alg, hex string) Digest {
+	return NewDigestFromEncoded(Algorithm(alg), hex)
+}
+
+// NewDigestFromEncoded returns a Digest from alg and the encoded digest.
+func NewDigestFromEncoded(alg Algorithm, encoded string) Digest {
+	return Digest(fmt.Sprintf("%s:%s", alg, encoded))
+}
+
+// DigestRegexp matches valid digest types.
+var DigestRegexp = regexp.MustCompile(`[a-z0-9]+(?:[.+_-][a-z0-9]+)*:[a-zA-Z0-9=_-]+`)
+
+// DigestRegexpAnchored matches valid digest types, anchored to the start and end of the match.
+var DigestRegexpAnchored = regexp.MustCompile(`^` + DigestRegexp.String() + `$`)
+
+var (
+	// ErrDigestInvalidFormat returned when digest format invalid.
+	ErrDigestInvalidFormat = fmt.Errorf("invalid checksum digest format")
+
+	// ErrDigestInvalidLength returned when digest has invalid length.
+	ErrDigestInvalidLength = fmt.Errorf("invalid checksum digest length")
+
+	// ErrDigestUnsupported returned when the digest algorithm is unsupported.
+	ErrDigestUnsupported = fmt.Errorf("unsupported digest algorithm")
+)
+
+// Parse parses s and returns the validated digest object. An error will
+// be returned if the format is invalid.
+func Parse(s string) (Digest, error) {
+	d := Digest(s)
+	return d, d.Validate()
+}
+
+// FromReader consumes the content of rd until io.EOF, returning canonical digest.
+func FromReader(rd io.Reader) (Digest, error) {
+	return Canonical.FromReader(rd)
+}
+
+// FromBytes digests the input and returns a Digest.
+func FromBytes(p []byte) Digest {
+	return Canonical.FromBytes(p)
+}
+
+// FromString digests the input and returns a Digest.
+func FromString(s string) Digest {
+	return Canonical.FromString(s)
+}
+
+// Validate checks that the contents of d is a valid digest, returning an
+// error if not.
+func (d Digest) Validate() error {
+	s := string(d)
+	i := strings.Index(s, ":")
+	if i <= 0 || i+1 == len(s) {
+		return ErrDigestInvalidFormat
+	}
+	algorithm, encoded := Algorithm(s[:i]), s[i+1:]
+	if !algorithm.Available() {
+		if !DigestRegexpAnchored.MatchString(s) {
+			return ErrDigestInvalidFormat
+		}
+		return ErrDigestUnsupported
+	}
+	return algorithm.Validate(encoded)
+}
+
+// Algorithm returns the algorithm portion of the digest. This will panic if
+// the underlying digest is not in a valid format.
+func (d Digest) Algorithm() Algorithm {
+	return Algorithm(d[:d.sepIndex()])
+}
+
+// Verifier returns a writer object that can be used to verify a stream of
+// content against the digest. If the digest is invalid, the method will panic.
+func (d Digest) Verifier() Verifier {
+	return hashVerifier{
+		hash:   d.Algorithm().Hash(),
+		digest: d,
+	}
+}
+
+// Encoded returns the encoded portion of the digest. This will panic if the
+// underlying digest is not in a valid format.
+func (d Digest) Encoded() string {
+	return string(d[d.sepIndex()+1:])
+}
+
+// Hex is deprecated. Please use Digest.Encoded.
+func (d Digest) Hex() string {
+	return d.Encoded()
+}
+
+func (d Digest) String() string {
+	return string(d)
+}
+
+func (d Digest) sepIndex() int {
+	i := strings.Index(string(d), ":")
+
+	if i < 0 {
+		panic(fmt.Sprintf("no ':' separator in digest %q", d))
+	}
+
+	return i
+}
diff --git a/vendor/github.com/opencontainers/go-digest/digester.go b/vendor/github.com/opencontainers/go-digest/digester.go
new file mode 100644
index 0000000..ede9077
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/digester.go
@@ -0,0 +1,40 @@
+// Copyright 2019, 2020 OCI Contributors
+// Copyright 2017 Docker, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package digest
+
+import "hash"
+
+// Digester calculates the digest of written data. Writes should go directly
+// to the return value of Hash, while calling Digest will return the current
+// value of the digest.
+type Digester interface {
+	Hash() hash.Hash // provides direct access to underlying hash instance.
+	Digest() Digest
+}
+
+// digester provides a simple digester definition that embeds a hasher.
+type digester struct {
+	alg  Algorithm
+	hash hash.Hash
+}
+
+func (d *digester) Hash() hash.Hash {
+	return d.hash
+}
+
+func (d *digester) Digest() Digest {
+	return NewDigest(d.alg, d.hash)
+}
diff --git a/vendor/github.com/opencontainers/go-digest/doc.go b/vendor/github.com/opencontainers/go-digest/doc.go
new file mode 100644
index 0000000..83d3a93
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/doc.go
@@ -0,0 +1,62 @@
+// Copyright 2019, 2020 OCI Contributors
+// Copyright 2017 Docker, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package digest provides a generalized type to opaquely represent message
+// digests and their operations within the registry. The Digest type is
+// designed to serve as a flexible identifier in a content-addressable system.
+// More importantly, it provides tools and wrappers to work with
+// hash.Hash-based digests with little effort.
+//
+// Basics
+//
+// The format of a digest is simply a string with two parts, dubbed the
+// "algorithm" and the "digest", separated by a colon:
+//
+// 	<algorithm>:<digest>
+//
+// An example of a sha256 digest representation follows:
+//
+// 	sha256:7173b809ca12ec5dee4506cd86be934c4596dd234ee82c0662eac04a8c2c71dc
+//
+// The "algorithm" portion defines both the hashing algorithm used to calculate
+// the digest and the encoding of the resulting digest, which defaults to "hex"
+// if not otherwise specified. Currently, all supported algorithms have their
+// digests encoded in hex strings.
+//
+// In the example above, the string "sha256" is the algorithm and the hex bytes
+// are the "digest".
+//
+// Because the Digest type is simply a string, once a valid Digest is
+// obtained, comparisons are cheap, quick and simple to express with the
+// standard equality operator.
+//
+// Verification
+//
+// The main benefit of using the Digest type is simple verification against a
+// given digest. The Verifier interface, modeled after the stdlib hash.Hash
+// interface, provides a common write sink for digest verification. After
+// writing is complete, calling the Verifier.Verified method will indicate
+// whether or not the stream of bytes matches the target digest.
+//
+// Missing Features
+//
+// In addition to the above, we intend to add the following features to this
+// package:
+//
+// 1. A Digester type that supports write sink digest calculation.
+//
+// 2. Suspend and resume of ongoing digest calculations to support efficient digest verification in the registry.
+//
+package digest
diff --git a/vendor/github.com/opencontainers/go-digest/verifiers.go b/vendor/github.com/opencontainers/go-digest/verifiers.go
new file mode 100644
index 0000000..afef506
--- /dev/null
+++ b/vendor/github.com/opencontainers/go-digest/verifiers.go
@@ -0,0 +1,46 @@
+// Copyright 2019, 2020 OCI Contributors
+// Copyright 2017 Docker, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package digest
+
+import (
+	"hash"
+	"io"
+)
+
+// Verifier presents a general verification interface to be used with message
+// digests and other byte stream verifications. Users instantiate a Verifier
+// from one of the various methods, write the data under test to it then check
+// the result with the Verified method.
+type Verifier interface {
+	io.Writer
+
+	// Verified will return true if the content written to Verifier matches
+	// the digest.
+	Verified() bool
+}
+
+type hashVerifier struct {
+	digest Digest
+	hash   hash.Hash
+}
+
+func (hv hashVerifier) Write(p []byte) (n int, err error) {
+	return hv.hash.Write(p)
+}
+
+func (hv hashVerifier) Verified() bool {
+	return hv.digest == NewDigest(hv.digest.Algorithm(), hv.hash)
+}
diff --git a/vendor/github.com/opencontainers/image-spec/LICENSE b/vendor/github.com/opencontainers/image-spec/LICENSE
new file mode 100644
index 0000000..9fdc20f
--- /dev/null
+++ b/vendor/github.com/opencontainers/image-spec/LICENSE
@@ -0,0 +1,191 @@
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   Copyright 2016 The Linux Foundation.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
diff --git a/vendor/github.com/opencontainers/image-spec/specs-go/v1/annotations.go b/vendor/github.com/opencontainers/image-spec/specs-go/v1/annotations.go
new file mode 100644
index 0000000..581cf7c
--- /dev/null
+++ b/vendor/github.com/opencontainers/image-spec/specs-go/v1/annotations.go
@@ -0,0 +1,62 @@
+// Copyright 2016 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v1
+
+const (
+	// AnnotationCreated is the annotation key for the date and time on which the image was built (date-time string as defined by RFC 3339).
+	AnnotationCreated = "org.opencontainers.image.created"
+
+	// AnnotationAuthors is the annotation key for the contact details of the people or organization responsible for the image (freeform string).
+	AnnotationAuthors = "org.opencontainers.image.authors"
+
+	// AnnotationURL is the annotation key for the URL to find more information on the image.
+	AnnotationURL = "org.opencontainers.image.url"
+
+	// AnnotationDocumentation is the annotation key for the URL to get documentation on the image.
+	AnnotationDocumentation = "org.opencontainers.image.documentation"
+
+	// AnnotationSource is the annotation key for the URL to get source code for building the image.
+	AnnotationSource = "org.opencontainers.image.source"
+
+	// AnnotationVersion is the annotation key for the version of the packaged software.
+	// The version MAY match a label or tag in the source code repository.
+	// The version MAY be Semantic versioning-compatible.
+	AnnotationVersion = "org.opencontainers.image.version"
+
+	// AnnotationRevision is the annotation key for the source control revision identifier for the packaged software.
+	AnnotationRevision = "org.opencontainers.image.revision"
+
+	// AnnotationVendor is the annotation key for the name of the distributing entity, organization or individual.
+	AnnotationVendor = "org.opencontainers.image.vendor"
+
+	// AnnotationLicenses is the annotation key for the license(s) under which contained software is distributed as an SPDX License Expression.
+	AnnotationLicenses = "org.opencontainers.image.licenses"
+
+	// AnnotationRefName is the annotation key for the name of the reference for a target.
+	// SHOULD only be considered valid when on descriptors on `index.json` within image layout.
+	AnnotationRefName = "org.opencontainers.image.ref.name"
+
+	// AnnotationTitle is the annotation key for the human-readable title of the image.
+	AnnotationTitle = "org.opencontainers.image.title"
+
+	// AnnotationDescription is the annotation key for the human-readable description of the software packaged in the image.
+	AnnotationDescription = "org.opencontainers.image.description"
+
+	// AnnotationBaseImageDigest is the annotation key for the digest of the image's base image.
+	AnnotationBaseImageDigest = "org.opencontainers.image.base.digest"
+
+	// AnnotationBaseImageName is the annotation key for the image reference of the image's base image.
+	AnnotationBaseImageName = "org.opencontainers.image.base.name"
+)
diff --git a/vendor/github.com/opencontainers/image-spec/specs-go/v1/config.go b/vendor/github.com/opencontainers/image-spec/specs-go/v1/config.go
new file mode 100644
index 0000000..36b0aeb
--- /dev/null
+++ b/vendor/github.com/opencontainers/image-spec/specs-go/v1/config.go
@@ -0,0 +1,111 @@
+// Copyright 2016 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v1
+
+import (
+	"time"
+
+	digest "github.com/opencontainers/go-digest"
+)
+
+// ImageConfig defines the execution parameters which should be used as a base when running a container using an image.
+type ImageConfig struct {
+	// User defines the username or UID which the process in the container should run as.
+	User string `json:"User,omitempty"`
+
+	// ExposedPorts a set of ports to expose from a container running this image.
+	ExposedPorts map[string]struct{} `json:"ExposedPorts,omitempty"`
+
+	// Env is a list of environment variables to be used in a container.
+	Env []string `json:"Env,omitempty"`
+
+	// Entrypoint defines a list of arguments to use as the command to execute when the container starts.
+	Entrypoint []string `json:"Entrypoint,omitempty"`
+
+	// Cmd defines the default arguments to the entrypoint of the container.
+	Cmd []string `json:"Cmd,omitempty"`
+
+	// Volumes is a set of directories describing where the process is likely write data specific to a container instance.
+	Volumes map[string]struct{} `json:"Volumes,omitempty"`
+
+	// WorkingDir sets the current working directory of the entrypoint process in the container.
+	WorkingDir string `json:"WorkingDir,omitempty"`
+
+	// Labels contains arbitrary metadata for the container.
+	Labels map[string]string `json:"Labels,omitempty"`
+
+	// StopSignal contains the system call signal that will be sent to the container to exit.
+	StopSignal string `json:"StopSignal,omitempty"`
+
+	// ArgsEscaped
+	//
+	// Deprecated: This field is present only for legacy compatibility with
+	// Docker and should not be used by new image builders.  It is used by Docker
+	// for Windows images to indicate that the `Entrypoint` or `Cmd` or both,
+	// contains only a single element array, that is a pre-escaped, and combined
+	// into a single string `CommandLine`. If `true` the value in `Entrypoint` or
+	// `Cmd` should be used as-is to avoid double escaping.
+	// https://github.com/opencontainers/image-spec/pull/892
+	ArgsEscaped bool `json:"ArgsEscaped,omitempty"`
+}
+
+// RootFS describes a layer content addresses
+type RootFS struct {
+	// Type is the type of the rootfs.
+	Type string `json:"type"`
+
+	// DiffIDs is an array of layer content hashes (DiffIDs), in order from bottom-most to top-most.
+	DiffIDs []digest.Digest `json:"diff_ids"`
+}
+
+// History describes the history of a layer.
+type History struct {
+	// Created is the combined date and time at which the layer was created, formatted as defined by RFC 3339, section 5.6.
+	Created *time.Time `json:"created,omitempty"`
+
+	// CreatedBy is the command which created the layer.
+	CreatedBy string `json:"created_by,omitempty"`
+
+	// Author is the author of the build point.
+	Author string `json:"author,omitempty"`
+
+	// Comment is a custom message set when creating the layer.
+	Comment string `json:"comment,omitempty"`
+
+	// EmptyLayer is used to mark if the history item created a filesystem diff.
+	EmptyLayer bool `json:"empty_layer,omitempty"`
+}
+
+// Image is the JSON structure which describes some basic information about the image.
+// This provides the `application/vnd.oci.image.config.v1+json` mediatype when marshalled to JSON.
+type Image struct {
+	// Created is the combined date and time at which the image was created, formatted as defined by RFC 3339, section 5.6.
+	Created *time.Time `json:"created,omitempty"`
+
+	// Author defines the name and/or email address of the person or entity which created and is responsible for maintaining the image.
+	Author string `json:"author,omitempty"`
+
+	// Platform describes the platform which the image in the manifest runs on.
+	Platform
+
+	// Config defines the execution parameters which should be used as a base when running a container using the image.
+	Config ImageConfig `json:"config,omitempty"`
+
+	// RootFS references the layer content addresses used by the image.
+	RootFS RootFS `json:"rootfs"`
+
+	// History describes the history of each layer.
+	History []History `json:"history,omitempty"`
+}
diff --git a/vendor/github.com/opencontainers/image-spec/specs-go/v1/descriptor.go b/vendor/github.com/opencontainers/image-spec/specs-go/v1/descriptor.go
new file mode 100644
index 0000000..1881b11
--- /dev/null
+++ b/vendor/github.com/opencontainers/image-spec/specs-go/v1/descriptor.go
@@ -0,0 +1,80 @@
+// Copyright 2016-2022 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v1
+
+import digest "github.com/opencontainers/go-digest"
+
+// Descriptor describes the disposition of targeted content.
+// This structure provides `application/vnd.oci.descriptor.v1+json` mediatype
+// when marshalled to JSON.
+type Descriptor struct {
+	// MediaType is the media type of the object this schema refers to.
+	MediaType string `json:"mediaType"`
+
+	// Digest is the digest of the targeted content.
+	Digest digest.Digest `json:"digest"`
+
+	// Size specifies the size in bytes of the blob.
+	Size int64 `json:"size"`
+
+	// URLs specifies a list of URLs from which this object MAY be downloaded
+	URLs []string `json:"urls,omitempty"`
+
+	// Annotations contains arbitrary metadata relating to the targeted content.
+	Annotations map[string]string `json:"annotations,omitempty"`
+
+	// Data is an embedding of the targeted content. This is encoded as a base64
+	// string when marshalled to JSON (automatically, by encoding/json). If
+	// present, Data can be used directly to avoid fetching the targeted content.
+	Data []byte `json:"data,omitempty"`
+
+	// Platform describes the platform which the image in the manifest runs on.
+	//
+	// This should only be used when referring to a manifest.
+	Platform *Platform `json:"platform,omitempty"`
+
+	// ArtifactType is the IANA media type of this artifact.
+	ArtifactType string `json:"artifactType,omitempty"`
+}
+
+// Platform describes the platform which the image in the manifest runs on.
+type Platform struct {
+	// Architecture field specifies the CPU architecture, for example
+	// `amd64` or `ppc64le`.
+	Architecture string `json:"architecture"`
+
+	// OS specifies the operating system, for example `linux` or `windows`.
+	OS string `json:"os"`
+
+	// OSVersion is an optional field specifying the operating system
+	// version, for example on Windows `10.0.14393.1066`.
+	OSVersion string `json:"os.version,omitempty"`
+
+	// OSFeatures is an optional field specifying an array of strings,
+	// each listing a required OS feature (for example on Windows `win32k`).
+	OSFeatures []string `json:"os.features,omitempty"`
+
+	// Variant is an optional field specifying a variant of the CPU, for
+	// example `v7` to specify ARMv7 when architecture is `arm`.
+	Variant string `json:"variant,omitempty"`
+}
+
+// DescriptorEmptyJSON is the descriptor of a blob with content of `{}`.
+var DescriptorEmptyJSON = Descriptor{
+	MediaType: MediaTypeEmptyJSON,
+	Digest:    `sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a`,
+	Size:      2,
+	Data:      []byte(`{}`),
+}
diff --git a/vendor/github.com/opencontainers/image-spec/specs-go/v1/index.go b/vendor/github.com/opencontainers/image-spec/specs-go/v1/index.go
new file mode 100644
index 0000000..e2bed9d
--- /dev/null
+++ b/vendor/github.com/opencontainers/image-spec/specs-go/v1/index.go
@@ -0,0 +1,38 @@
+// Copyright 2016 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v1
+
+import "github.com/opencontainers/image-spec/specs-go"
+
+// Index references manifests for various platforms.
+// This structure provides `application/vnd.oci.image.index.v1+json` mediatype when marshalled to JSON.
+type Index struct {
+	specs.Versioned
+
+	// MediaType specifies the type of this document data structure e.g. `application/vnd.oci.image.index.v1+json`
+	MediaType string `json:"mediaType,omitempty"`
+
+	// ArtifactType specifies the IANA media type of artifact when the manifest is used for an artifact.
+	ArtifactType string `json:"artifactType,omitempty"`
+
+	// Manifests references platform specific manifests.
+	Manifests []Descriptor `json:"manifests"`
+
+	// Subject is an optional link from the image manifest to another manifest forming an association between the image manifest and the other manifest.
+	Subject *Descriptor `json:"subject,omitempty"`
+
+	// Annotations contains arbitrary metadata for the image index.
+	Annotations map[string]string `json:"annotations,omitempty"`
+}
diff --git a/vendor/github.com/opencontainers/image-spec/specs-go/v1/layout.go b/vendor/github.com/opencontainers/image-spec/specs-go/v1/layout.go
new file mode 100644
index 0000000..c5503cb
--- /dev/null
+++ b/vendor/github.com/opencontainers/image-spec/specs-go/v1/layout.go
@@ -0,0 +1,32 @@
+// Copyright 2016 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v1
+
+const (
+	// ImageLayoutFile is the file name containing ImageLayout in an OCI Image Layout
+	ImageLayoutFile = "oci-layout"
+	// ImageLayoutVersion is the version of ImageLayout
+	ImageLayoutVersion = "1.0.0"
+	// ImageIndexFile is the file name of the entry point for references and descriptors in an OCI Image Layout
+	ImageIndexFile = "index.json"
+	// ImageBlobsDir is the directory name containing content addressable blobs in an OCI Image Layout
+	ImageBlobsDir = "blobs"
+)
+
+// ImageLayout is the structure in the "oci-layout" file, found in the root
+// of an OCI Image-layout directory.
+type ImageLayout struct {
+	Version string `json:"imageLayoutVersion"`
+}
diff --git a/vendor/github.com/opencontainers/image-spec/specs-go/v1/manifest.go b/vendor/github.com/opencontainers/image-spec/specs-go/v1/manifest.go
new file mode 100644
index 0000000..26fec52
--- /dev/null
+++ b/vendor/github.com/opencontainers/image-spec/specs-go/v1/manifest.go
@@ -0,0 +1,41 @@
+// Copyright 2016-2022 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v1
+
+import "github.com/opencontainers/image-spec/specs-go"
+
+// Manifest provides `application/vnd.oci.image.manifest.v1+json` mediatype structure when marshalled to JSON.
+type Manifest struct {
+	specs.Versioned
+
+	// MediaType specifies the type of this document data structure e.g. `application/vnd.oci.image.manifest.v1+json`
+	MediaType string `json:"mediaType,omitempty"`
+
+	// ArtifactType specifies the IANA media type of artifact when the manifest is used for an artifact.
+	ArtifactType string `json:"artifactType,omitempty"`
+
+	// Config references a configuration object for a container, by digest.
+	// The referenced configuration object is a JSON blob that the runtime uses to set up the container.
+	Config Descriptor `json:"config"`
+
+	// Layers is an indexed list of layers referenced by the manifest.
+	Layers []Descriptor `json:"layers"`
+
+	// Subject is an optional link from the image manifest to another manifest forming an association between the image manifest and the other manifest.
+	Subject *Descriptor `json:"subject,omitempty"`
+
+	// Annotations contains arbitrary metadata for the image manifest.
+	Annotations map[string]string `json:"annotations,omitempty"`
+}
diff --git a/vendor/github.com/opencontainers/image-spec/specs-go/v1/mediatype.go b/vendor/github.com/opencontainers/image-spec/specs-go/v1/mediatype.go
new file mode 100644
index 0000000..ce8313e
--- /dev/null
+++ b/vendor/github.com/opencontainers/image-spec/specs-go/v1/mediatype.go
@@ -0,0 +1,85 @@
+// Copyright 2016 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v1
+
+const (
+	// MediaTypeDescriptor specifies the media type for a content descriptor.
+	MediaTypeDescriptor = "application/vnd.oci.descriptor.v1+json"
+
+	// MediaTypeLayoutHeader specifies the media type for the oci-layout.
+	MediaTypeLayoutHeader = "application/vnd.oci.layout.header.v1+json"
+
+	// MediaTypeImageIndex specifies the media type for an image index.
+	MediaTypeImageIndex = "application/vnd.oci.image.index.v1+json"
+
+	// MediaTypeImageManifest specifies the media type for an image manifest.
+	MediaTypeImageManifest = "application/vnd.oci.image.manifest.v1+json"
+
+	// MediaTypeImageConfig specifies the media type for the image configuration.
+	MediaTypeImageConfig = "application/vnd.oci.image.config.v1+json"
+
+	// MediaTypeEmptyJSON specifies the media type for an unused blob containing the value "{}".
+	MediaTypeEmptyJSON = "application/vnd.oci.empty.v1+json"
+)
+
+const (
+	// MediaTypeImageLayer is the media type used for layers referenced by the manifest.
+	MediaTypeImageLayer = "application/vnd.oci.image.layer.v1.tar"
+
+	// MediaTypeImageLayerGzip is the media type used for gzipped layers
+	// referenced by the manifest.
+	MediaTypeImageLayerGzip = "application/vnd.oci.image.layer.v1.tar+gzip"
+
+	// MediaTypeImageLayerZstd is the media type used for zstd compressed
+	// layers referenced by the manifest.
+	MediaTypeImageLayerZstd = "application/vnd.oci.image.layer.v1.tar+zstd"
+)
+
+// Non-distributable layer media-types.
+//
+// Deprecated: Non-distributable layers are deprecated, and not recommended
+// for future use. Implementations SHOULD NOT produce new non-distributable
+// layers.
+// https://github.com/opencontainers/image-spec/pull/965
+const (
+	// MediaTypeImageLayerNonDistributable is the media type for layers referenced by
+	// the manifest but with distribution restrictions.
+	//
+	// Deprecated: Non-distributable layers are deprecated, and not recommended
+	// for future use. Implementations SHOULD NOT produce new non-distributable
+	// layers.
+	// https://github.com/opencontainers/image-spec/pull/965
+	MediaTypeImageLayerNonDistributable = "application/vnd.oci.image.layer.nondistributable.v1.tar"
+
+	// MediaTypeImageLayerNonDistributableGzip is the media type for
+	// gzipped layers referenced by the manifest but with distribution
+	// restrictions.
+	//
+	// Deprecated: Non-distributable layers are deprecated, and not recommended
+	// for future use. Implementations SHOULD NOT produce new non-distributable
+	// layers.
+	// https://github.com/opencontainers/image-spec/pull/965
+	MediaTypeImageLayerNonDistributableGzip = "application/vnd.oci.image.layer.nondistributable.v1.tar+gzip"
+
+	// MediaTypeImageLayerNonDistributableZstd is the media type for zstd
+	// compressed layers referenced by the manifest but with distribution
+	// restrictions.
+	//
+	// Deprecated: Non-distributable layers are deprecated, and not recommended
+	// for future use. Implementations SHOULD NOT produce new non-distributable
+	// layers.
+	// https://github.com/opencontainers/image-spec/pull/965
+	MediaTypeImageLayerNonDistributableZstd = "application/vnd.oci.image.layer.nondistributable.v1.tar+zstd"
+)
diff --git a/vendor/github.com/opencontainers/image-spec/specs-go/version.go b/vendor/github.com/opencontainers/image-spec/specs-go/version.go
new file mode 100644
index 0000000..c3897c7
--- /dev/null
+++ b/vendor/github.com/opencontainers/image-spec/specs-go/version.go
@@ -0,0 +1,32 @@
+// Copyright 2016 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package specs
+
+import "fmt"
+
+const (
+	// VersionMajor is for an API incompatible changes
+	VersionMajor = 1
+	// VersionMinor is for functionality in a backwards-compatible manner
+	VersionMinor = 1
+	// VersionPatch is for backwards-compatible bug fixes
+	VersionPatch = 1
+
+	// VersionDev indicates development branch. Releases will be empty string.
+	VersionDev = ""
+)
+
+// Version is the specification version that the package types support.
+var Version = fmt.Sprintf("%d.%d.%d%s", VersionMajor, VersionMinor, VersionPatch, VersionDev)
diff --git a/vendor/github.com/opencontainers/image-spec/specs-go/versioned.go b/vendor/github.com/opencontainers/image-spec/specs-go/versioned.go
new file mode 100644
index 0000000..58a1510
--- /dev/null
+++ b/vendor/github.com/opencontainers/image-spec/specs-go/versioned.go
@@ -0,0 +1,23 @@
+// Copyright 2016 The Linux Foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package specs
+
+// Versioned provides a struct with the manifest schemaVersion and mediaType.
+// Incoming content with unknown schema version can be decoded against this
+// struct to check the version.
+type Versioned struct {
+	// SchemaVersion is the image manifest schema that this image follows
+	SchemaVersion int `json:"schemaVersion"`
+}