CNAB to OCI

The intent of CNAB to OCI is to propose a library for sharing a CNAB using an OCI or Docker registry.

Getting Started

To get and build the project:

$ go get -u github.com/docker/cnab-to-oci
$ cd $GOPATH/src/github.com/docker/cnab-to-oci
$ make

You should now have a cnab-to-oci binary the bin/ folder. To run it, execute:

$ bin/cnab-to-oci --help

Prerequisites

Make
Golang 1.9+
Git

Installing

For installing, make sure your $GOPATH/bin is part of your $PATH.

$ make install

This will build and install cnab-to-oci into $GOPATH/bin.

Usage

The cnab-to-oci binary is a demonstration tool to push and pull a CNAB to a registry. It has three commands: push, pull and fixup which are described in the following sections.

Push

The push command packages a bundle.json file into an OCI image index (falling back to a Docker manifest if the registry does not support this) and pushes this to the registry. As part of this process, fixup process is implicitly run.

$ bin/cnab-to-oci push examples/helloworld-cnab/bundle.json --target myhubusername/repo
Ensuring image cnab/helloworld:0.1.1 is present in repository docker.io/myhubusername/repo
Image is not present in repository
Mounting descriptor sha256:bbffe37bb3899b1384bf1483cdcff44bd148d52078b4655e69cd23d534ea043d with media type application/vnd.docker.image.rootfs.diff.tar.gzip (size: 203)
Mounting descriptor sha256:e280b57a032b8bb2ab45f26ea67f42b5d47fd5aca2dd63c5bcdbbd1f753f20b7 with media type application/vnd.docker.image.rootfs.diff.tar.gzip (size: 370)
Mounting descriptor sha256:8e3ba11ec2a2b39ab372c60c16b421536e50e5ce64a0bc81765c2e38381bcff6 with media type application/vnd.docker.image.rootfs.diff.tar.gzip (size: 2206542)
Mounting descriptor sha256:58e6f39290459b6563b348052b2a1a8cf2a44fac19a80ae0da36c82a32f151f8 with media type application/vnd.docker.container.image.v1+json (size: 2135)
Copying descriptor sha256:a59a4e74d9cc89e4e75dfb2cc7ea5c108e4236ba6231b53081a9e2506d1197b6 with media type application/vnd.docker.distribution.manifest.v2+json (size: 942)
{"errors":[{"code":"MANIFEST_INVALID","message":"manifest invalid","detail":{}}]}

Pushed successfully, with digest "sha256:6cabd752cb01d2efb9485225baf7fc26f4322c1f45f537f76c5eeb67ba8d83e0"

Note: cnab-to-oci does not push images from your docker daemon image store. Make sure all your invocation images are already present on a registry before pushing your bundle.

Note: The MANIFEST_INVALID error in the above case is because the Docker Hub does not currently support the OCI image index type.

Note: When using the Docker Hub, no tag will show up in the Hub interface. The artifact must be referenced by its SHA - see pull.

Pull

The pull command is used to fetch a CNAB packaged as an OCI image index or Docker manifest from a registry. This must be done using the digest returned by the push command. By default the output is saved to pulled.json.

$ bin/cnab-to-oci pull myhubusername/repo@sha256:6cabd752cb01d2efb9485225baf7fc26f4322c1f45f537f76c5eeb67ba8d83e0

$ cat pulled.json
{
 "name": "helloworld",
 "version": "0.1.1",
 "description": "A short description of your bundle",
 "keywords": [
  "helloworld",
  "cnab",
  "tutorial"
 ],
 "maintainers": [
  {
   "name": "Jane Doe",
   "email": "jane.doe@example.com",
   "url": "https://example.com"
  }
 ],
 "invocationImages": [
  {
   "imageType": "docker",
   "image": "myhubusername/repo@sha256:a59a4e74d9cc89e4e75dfb2cc7ea5c108e4236ba6231b53081a9e2506d1197b6",
   "size": 942,
   "mediaType": "application/vnd.docker.distribution.manifest.v2+json"
  }
 ],
 "images": null,
 "parameters": null,
 "credentials": null
}

Fixup

The fixup command resolves all the image digest references (for the invocationImages as well as the images in the bundle.json) from the relevant registries and pushes them to the target repository to ensure they're available to anyone who has access to the CNAB in the target repository. A patched bundle.json is saved by default to fixed-bundle.json

$ bin/cnab-to-oci fixup examples/helloworld-cnab/bundle.json --target myhubusername/repo
Ensuring image cnab/helloworld:0.1.1 is present in repository docker.io/myhubusername/repo
Image is not present in repository
Mounting descriptor sha256:bbffe37bb3899b1384bf1483cdcff44bd148d52078b4655e69cd23d534ea043d with media type application/vnd.docker.image.rootfs.diff.tar.gzip (size: 203)
Mounting descriptor sha256:e280b57a032b8bb2ab45f26ea67f42b5d47fd5aca2dd63c5bcdbbd1f753f20b7 with media type application/vnd.docker.image.rootfs.diff.tar.gzip (size: 370)
Mounting descriptor sha256:8e3ba11ec2a2b39ab372c60c16b421536e50e5ce64a0bc81765c2e38381bcff6 with media type application/vnd.docker.image.rootfs.diff.tar.gzip (size: 2206542)
Mounting descriptor sha256:58e6f39290459b6563b348052b2a1a8cf2a44fac19a80ae0da36c82a32f151f8 with media type application/vnd.docker.container.image.v1+json (size: 2135)
Copying descriptor sha256:a59a4e74d9cc89e4e75dfb2cc7ea5c108e4236ba6231b53081a9e2506d1197b6 with media type application/vnd.docker.distribution.manifest.v2+json (size: 942)

$ cat fixed-bundle.json
{
  "name": "helloworld",
  "version": "0.1.1",
  "description": "A short description of your bundle",
  "keywords": [
    "helloworld",
    "cnab",
    "tutorial"
  ],
  "maintainers": [
    {
      "name": "Jane Doe",
      "email": "jane.doe@example.com",
      "url": "https://example.com"
    }
  ],
  "invocationImages": [
    {
      "imageType": "docker",
      "image": "myhubusername/repo@sha256:a59a4e74d9cc89e4e75dfb2cc7ea5c108e4236ba6231b53081a9e2506d1197b6",
      "size": 942,
      "mediaType": "application/vnd.docker.distribution.manifest.v2+json"
    }
  ],
  "images": null,
  "parameters": null,
  "credentials": null
}

Note: In the above example, the invocation image reference now matches the target repository.

Example

The following is an example of an OCI image index sent to the registry.

{
  "schemaVersion": 1,
  "manifests": [
    {
      "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
      "digest": "sha256:d59a1aa7866258751a261bae525a1842c7ff0662d4f34a355d5f36826abc0341",
      "size": 315,
      "annotations": {
        "io.cnab.type": "config"
      }
    },
    {
      "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
      "digest": "sha256:196d12cf6ab19273823e700516e98eb1910b03b17840f9d5509f03858484d321",
      "size": 506,
      "annotations": {
        "io.cnab.type": "invocation"
      }
    },
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "digest": "sha256:6bb891430fb6e2d3b4db41fd1f7ece08c5fc769d8f4823ec33c7c7ba99679213",
      "size": 507,
      "annotations": {
        "io.cnab.component_name": "image-1",
        "io.cnab.original_name": "nginx:2.12",
        "io.cnab.type": "component"
      }
    }
  ],
  "annotations": {
    "io.cnab.keywords": "[\"keyword1\",\"keyword2\"]",
    "io.cnab.runtime_version": "v1.0.0-WD",
    "io.docker.app.format": "cnab",
    "io.docker.type": "app",
    "org.opencontainers.image.authors": "[{\"name\":\"docker\",\"email\":\"docker@docker.com\",\"url\":\"docker.com\"}]",
    "org.opencontainers.image.description": "description",
    "org.opencontainers.image.title": "my-app",
    "org.opencontainers.image.version": "0.1.0"
  }
}

Development

Running the tests

$ make test

Running the e2e tests

$ make e2e

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.

Maintainers

See also the list of maintainers who participated in this project.

Contributors

See also the list of contributors who participated in this project.

License

This project is licensed under the Apache 2 License - see the LICENSE file for details.

ebriney / cnab-to-oci