Viewing Logs

To view the logs for the Docker registry, use the oc logs command with the deployment config:

$ oc logs dc/docker-registry
2015-05-01T19:48:36.300593110Z time="2015-05-01T19:48:36Z" level=info msg="version=v2.0.0+unknown"
2015-05-01T19:48:36.303294724Z time="2015-05-01T19:48:36Z" level=info msg="redis not configured"
2015-05-01T19:48:36.303422845Z time="2015-05-01T19:48:36Z" level=info msg="using inmemory layerinfo cache"
2015-05-01T19:48:36.303433991Z time="2015-05-01T19:48:36Z" level=info msg="Using OpenShift Auth handler"
2015-05-01T19:48:36.303439084Z time="2015-05-01T19:48:36Z" level=info msg="listening on :5000"

File Storage

Tag and image metadata is stored in OpenShift Origin, but the registry stores layer and signature data in a volume that is mounted into the registry container at /registry. As oc exec does not work on privileged containers, to view a registry’s contents you must manually SSH into the node housing the registry pod’s container, then run docker exec on the container itself:

  1. List the current pods to find the pod name of your Docker registry:

    # oc get pods

    Then, use oc describe to find the host name for the node running the container:

    # oc describe pod <pod_name>
  2. Log into the desired node:

    # ssh
  3. List the running containers on the node host and identify the container ID for the Docker registry:

    # docker ps | grep ose-docker-registry
  4. List the registry contents using the docker exec command:

    # docker exec -it 4c01db0b339c find /registry
    /registry/docker/registry/v2/blobs (1)
    /registry/docker/registry/v2/blobs/sha256/ed/ede17b139a271d6b1331ca3d83c648c24f92cece5f89d95ac6c34ce751111810/data (2)
    /registry/docker/registry/v2/repositories (3)
    /registry/docker/registry/v2/repositories/p1/pause (4)
    /registry/docker/registry/v2/repositories/p1/pause/_manifests/revisions/sha256/e9a2ac6418981897b399d3709f1b4a6d2723cd38a4909215ce2752a5c068b1cf/signatures (5)
    /registry/docker/registry/v2/repositories/p1/pause/_manifests/revisions/sha256/e9a2ac6418981897b399d3709f1b4a6d2723cd38a4909215ce2752a5c068b1cf/signatures/sha256/ede17b139a271d6b1331ca3d83c648c24f92cece5f89d95ac6c34ce751111810/link (6)
    /registry/docker/registry/v2/repositories/p1/pause/_uploads (7)
    /registry/docker/registry/v2/repositories/p1/pause/_layers (8)
    /registry/docker/registry/v2/repositories/p1/pause/_layers/sha256/a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4/link (9)
    1 This directory stores all layers and signatures as blobs.
    2 This file contains the blob’s contents.
    3 This directory stores all the image repositories.
    4 This directory is for a single image repository p1/pause.
    5 This directory contains signatures for a particular image manifest revision.
    6 This file contains a reference back to a blob (which contains the signature data).
    7 This directory contains any layers that are currently being uploaded and staged for the given repository.
    8 This directory contains links to all the layers this repository references.
    9 This file contains a reference to a specific layer that has been linked into this repository via an image.

Accessing the Registry Directly

For advanced usage, you can access the registry directly to invoke docker commands. This allows you to push images to or pull them from the integrated registry directly using operations like docker push or docker pull. To do so, you must be logged in to the registry using the docker login command. The operations you can perform depend on your user permissions, as described in the following sections.

User Prerequisites

To access the registry directly, the user that you use must satisfy the following, depending on your intended usage:

  • For any direct access, you must have a regular user, if one does not already exist, for your preferred identity provider. A regular user can generate an access token required for logging in to the registry. System users, such as system:admin, cannot obtain access tokens and, therefore, cannot access the registry directly.

    For example, if you are using HTPASSWD authentication, you can create one using the following command:

    # htpasswd /etc/origin/openshift-htpasswd <user_name>
  • The user must have the system:registry role. To add this role:

    # oadm policy add-role-to-user system:registry <user_name>
  • Have the admin role for the project associated with the Docker operation. For example, if accessing images in the global openshift project:

     $ oadm policy add-role-to-user admin <user_name> -n openshift
  • For writing or pushing images, for example when using the docker push command, the user must have the system:image-builder role. To add this role:

    $ oadm policy add-role-to-user system:image-builder <user_name>

For more information on user permissions, see Managing Role Bindings.

Logging in to the Registry

Ensure your user satisfies the prerequisites for accessing the registry directly.

To log in to the registry directly:

  1. Ensure you are logged in to OpenShift Origin as a regular user:

    $ oc login
  2. Get your access token:

    $ oc whoami -t
  3. Log in to the Docker registry:

    $ docker login -u <username> -e <any_email_address> \
        -p <token_value> <registry_ip>:<port>

Pushing and Pulling Images

After logging in to the registry, you can perform docker pull and docker push operations against your registry.

You can pull arbitrary images, but if you have the system:registry role added, you can only push images to the registry in your project.

In the following examples, we use:











omitted (defaults to latest)

  1. Pull an arbitrary image:

    $ docker pull
  2. Tag the new image with the form <registry_ip>:<port>/<project>/<image>. The project name must appear in this pull specification for OpenShift Origin to correctly place and later access the image in the registry.

    $ docker tag

    Your regular user must have the system:image-builder role for the specified project, which allows the user to write or push an image. Otherwise, the docker push in the next step will fail. To test, you can create a new project to push the busybox image.

  3. Push the newly-tagged image to your registry:

    $ docker push
    cf2616975b4a: Image successfully pushed
    Digest: sha256:3662dd821983bc4326bee12caec61367e7fb6f6a3ee547cbaff98f77403cab55

Accessing Registry Metrics

The OpenShift Container Registry provides an endpoint for Prometheus metrics. Prometheus is a stand-alone, open source systems monitoring and alerting toolkit.

The metrics are exposed at the /extensions/v2/metrics path of the registry endpoint. However, this route must first be enabled; see Extended Registry Configuration for instructions.

The following is a simple example of a metrics query:

$ curl -s -u <user>:<secret> \ (1) | grep openshift | head -n 10

# HELP openshift_build_info A metric with a constant '1' value labeled by major, minor, git commit & git version from which OpenShift was built.
# TYPE openshift_build_info gauge
openshift_build_info{gitCommit="67275e1",gitVersion="v3.6.0-alpha.1+67275e1-803",major="3",minor="6+"} 1
# HELP openshift_registry_request_duration_seconds Request latency summary in microseconds for each operation
# TYPE openshift_registry_request_duration_seconds summary
openshift_registry_request_duration_seconds{name="test/origin-pod",operation="blobstore.create",quantile="0.5"} 0
openshift_registry_request_duration_seconds{name="test/origin-pod",operation="blobstore.create",quantile="0.9"} 0
openshift_registry_request_duration_seconds{name="test/origin-pod",operation="blobstore.create",quantile="0.99"} 0
openshift_registry_request_duration_seconds_sum{name="test/origin-pod",operation="blobstore.create"} 0
openshift_registry_request_duration_seconds_count{name="test/origin-pod",operation="blobstore.create"} 5
1 <user> can be arbitrary, but <secret> must match the value specified in the registry configuration.

See the upstream Prometheus documentation for more advanced queries and recommended visualizers.