Registry Image Resource

Supports checking, fetching, and pushing of images to Docker registries.

This resource is intended as a replacement for the Docker Image resource. Here are the key differences:

• This resource is implemented in pure Go and does not use the Docker daemon or CLI. This makes it safer (no need for privileged: true), more efficient, and less error-prone (now that we're using Go APIs and not parsing docker CLI output).

• This resource has stronger test coverage.

• This resource does not and will never support building - only registry image pushing/pulling. Building should instead be done with something like the oci-build task (or anything that can produce OCI image tarballs).

• A goal of this resource is to stay as focused and simple as possible. The Docker Image resource grew way too large and complicated. There are simply too many ways to build and publish Docker images. It will be easier to support many smaller resources + tasks rather than one huge interface.

Source Configuration

• repository: Required. The name of the repository, e.g. alpine. If using ecr you only need the repository name, not the full URI e.g. alpine not 012345678910.dkr.ecr.us-east-1.amazonaws.com/alpine

• tag: Optional. Default latest. The name of the tag to monitor and publish to.

• username and password: Optional. A username and password to use when authenticating to the registry. Must be specified for private repos or when using put.

• aws_access_key_id: Optional. Default "". The access key ID to use for authenticating with ECR.

• aws_secret_access_key: Optional. Default "". The secret access key to use for authenticating with ECR.

• aws_session_token: Optional. Default "". The session token to use for authenticating with STS credentials with ECR.

• aws_region: Optional. Default "". The region to use for accessing ECR. This is required if you are using ECR. This region will help determine the full repository URL you are accessing (e.g., 012345678910.dkr.ecr.us-east-1.amazonaws.com)

• aws_role_arn: Optional. Default "". If set, then this role will be assumed before authenticating to ECR.

• debug: Optional. Default false. If set, progress bars will be disabled and debugging output will be printed instead.

• registry_mirror: Optional.

  • host: Required. A hostname pointing to a Docker registry mirror service. Note that this is only used if no registry hostname prefix is specified in the repository. If the repository contains a registry hostname prefix -- such as my-registry.com/foo/bar -- the registry_mirror is ignored and the explicitly declared registry in the repository value is used.
  • username and password: Optional. A username and password to use when authenticating to the mirror.

• content_trust: Optional. Configuration about content trust.

  • server: Optional. URL for the notary server. (equal to DOCKER_CONTENT_TRUST_SERVER)
  • repository_key_id: Required. Target key's ID used to sign the trusted collection, could be retrieved by notary key list
  • repository_key: Required. Target key used to sign the trusted collection.
  • repository_passphrase: Required. The passphrase of the signing/target key. (equal to DOCKER_CONTENT_TRUST_REPOSITORY_PASSPHRASE)
  • tls_key: Optional. Default "" TLS key for the notary server.
  • tls_cert: Optional. Default "" TLS certificate for the notary server.

Signing with Docker Hub

Configure Docker Content Trust for use with the Docker Hub and Notary service by specifying the above source parameters as follows:

• repository_key should be set to the contents of the DCT key file located in your ~/.docker/trust/private directory.
• repository_key_id should be set to the full key itself, which is also the filename of the key file mentioned above, without the .key extension.

Consider the following resource:

resources:
- name: trusted-image
  type: registry-image
  source:
    repository: docker.io/foo/bar
    username: ((registry_user))
    password: ((registry_pass))
    content_trust:
      repository_key_id: ((registry_key_id))
      repository_key: ((registry_key))
      repository_passphrase: ((registry_passphrase))

Specify the values for these variables as shown in the following static variable file, or preferrably in a configured credential manager:

registry_user: jertel
registry_pass: my_docker_hub_token
registry_passphrase: my_dct_key_passphrase
registry_key_id: 1452a842871e529ffc2be29a012618e1b2a0e6984a89e92e34b5a0fc21a04cd
registry_key: |
  -----BEGIN ENCRYPTED PRIVATE KEY-----
  role: jertel

  MIhsj2sd41fwaa...
  -----END ENCRYPTED PRIVATE KEY-----

NOTE This configuration only applies to the out action. check & in aren't impacted. Hence, it would be possible to check or use in to get unsigned images.

Behavior

check: Discover new digests.

Reports the current digest that the registry has for the tag configured in source.

in: Fetch the image's rootfs and metadata.

Fetches an image at a digest.

Parameters

• format: Optional. Default rootfs. The format to fetch as.
• skip_download: Optional. Default false. Skip downloading the image. Useful only to trigger a job without using the object.

Files created by the resource

The resource will produce the following files:

• ./digest: A file containing the image's digest, e.g. sha256:....
• ./tag: A file containing the tag from source, e.g. latest.

The remaining files depend on the configuration value for format:

rootfs

The rootfs format will fetch and unpack the image for use by Concourse task and resource type images.

This the default for the sake of brevity in pipelines and task configs.

In this format, the resource will produce the following files:

• ./rootfs/...: the unpacked rootfs produced by the image.
• ./metadata.json: the runtime information to propagate to Concourse.

oci

The oci format will fetch the image and write it to disk in OCI format. This is analogous to running docker save.

In this format, the resource will produce the following files:

• ./image.tar: the OCI image tarball, suitable for passing to docker load.

out: Push an image up to the registry under the given tags.

Uploads an image to the registry under the tag configured in source.

If additional_tags param is defined then the uploaded image will also be tagged with each one of the values specified in that file.

The currently encouraged way to build these images is by using the oci-build-task.

Parameters

• image: Required. The path to the OCI image tarball to upload. Expanded with filepath.Glob.
• additional_tags: Optional. The path to a file with whitespace-separated list of tag values to tag the image with (in addition to the tag configured in source).

Use in tasks

Images used as image resources in tasks are called anonymous resources. Anonymous resources can specify a version, which is the image digest. For example:

image_resource:
  type: docker-image
  source:
    repository: golang
  version:
    digest: 'sha256:5f640aeb8b78e9876546a9d06b928d2ad0c6e51900bcba10ff4e12dc57f6f265'

This is useful when the registry image does not have tags, or when the tags are going to be re-used.

Development

Prerequisites

• golang is required - version 1.11.x or above is required for go mod to work
• docker is required - version 17.06.x is tested; earlier versions may also work.
• go mod is used for dependency management of the golang packages.

Running the tests

The tests have been embedded with the Dockerfile; ensuring that the testing environment is consistent across any docker enabled platform. When the docker image builds, the test are run inside the docker container, on failure they will stop the build.

Run the tests with the following commands for both alpine and ubuntu images:

docker build -t registry-image-resource -f dockerfiles/alpine/Dockerfile .
docker build -t registry-image-resource -f dockerfiles/ubuntu/Dockerfile .

Integration tests

The integration requires 2 docker repos, one private and one public. The docker build step requires setting --build-args so the integration will run.

Run the tests with the following command:

docker build . -t registry-image-resource -f dockerfiles/alpine/Dockerfile \
  --build-arg DOCKER_PRIVATE_USERNAME="some-username" \
  --build-arg DOCKER_PRIVATE_PASSWORD="some-password" \
  --build-arg DOCKER_PRIVATE_REPO="some/repo" \
  --build-arg DOCKER_PUSH_USERNAME="some-username" \
  --build-arg DOCKER_PUSH_PASSWORD="some-password" \
  --build-arg DOCKER_PUSH_REPO="some/repo"

docker build . -t registry-image-resource -f dockerfiles/ubuntu/Dockerfile \
  --build-arg DOCKER_PRIVATE_USERNAME="some-username" \
  --build-arg DOCKER_PRIVATE_PASSWORD="some-password" \
  --build-arg DOCKER_PRIVATE_REPO="some/repo" \
  --build-arg DOCKER_PUSH_USERNAME="some-username" \
  --build-arg DOCKER_PUSH_PASSWORD="some-password" \
  --build-arg DOCKER_PUSH_REPO="some/repo"

Contributing

Please make all pull requests to the master branch and ensure tests pass locally.