Registry

Azure Red Hat OpenShift 4

Configuring registries for Azure Red Hat OpenShift 4

Red Hat OpenShift Documentation Team

Abstract

This document provides instructions for configuring and managing the internal registry for Azure Red Hat OpenShift 4. It also provides a general overview of registries associated with Azure Red Hat OpenShift 4.

Chapter 1. Image Registry

1.1. Integrated Azure Red Hat OpenShift registry

Azure Red Hat OpenShift provides a built in container image registry which runs as a standard workload on the cluster. The registry is configured and managed by an infrastructure operator. It provides an out of the box solution for users to manage the images that run their workloads, and runs on top of the existing cluster infrastructure. This registry can be scaled up or down like any other cluster workload and does not require specific infrastructure provisioning. In addition, it is integrated into the cluster user authentication and authorization system which means that access to create and retrieve images is controlled by defining user permissions on the image resources.

The registry is typically used as a publication target for images built on the cluster as well as a source of images for workloads running on the cluster. When a new image is pushed to the registry, the cluster is notified of the new image and other components can react to and consume the updated image.

Image data is stored in two locations. The actual image data is stored in a configurable storage location such as cloud storage or a filesystem volume. The image metadata, which is exposed by the standard cluster APIs and is used to perform access control, is stored as standard API resources, specifically images and imagestreams.

Chapter 2. Image Registry Operator in Azure Red Hat OpenShift

2.1. Image Registry on cloud platforms and OpenStack

The Image Registry Operator installs a single instance of the Azure Red Hat OpenShift registry, and manages all registry configuration, including setting up registry storage.

Note

Storage is only automatically configured when you install an installer-provisioned infrastructure cluster on AWS, GCP, Azure, or OpenStack.

After the control plane deploys, the Operator will create a default configs.imageregistry.operator.openshift.io resource instance based on configuration detected in the cluster.

If insufficient information is available to define a complete configs.imageregistry.operator.openshift.io resource, the incomplete resource will be defined and the operator will update the resource status with information about what is missing.

The Image Registry Operator runs in the openshift-image-registry namespace, and manages the registry instance in that location as well. All configuration and workload resources for the registry reside in that namespace.

Chapter 3. Registry options

Azure Red Hat OpenShift can build images from your source code, deploy them, and manage their lifecycle. To enable this, Azure Red Hat OpenShift provides an internal, integrated container image registry that can be deployed in your Azure Red Hat OpenShift environment to locally manage images.

3.1. Integrated Azure Red Hat OpenShift registry

Azure Red Hat OpenShift provides a built in container image registry which runs as a standard workload on the cluster. The registry is configured and managed by an infrastructure operator. It provides an out of the box solution for users to manage the images that run their workloads, and runs on top of the existing cluster infrastructure. This registry can be scaled up or down like any other cluster workload and does not require specific infrastructure provisioning. In addition, it is integrated into the cluster user authentication and authorization system which means that access to create and retrieve images is controlled by defining user permissions on the image resources.

The registry is typically used as a publication target for images built on the cluster as well as a source of images for workloads running on the cluster. When a new image is pushed to the registry, the cluster is notified of the new image and other components can react to and consume the updated image.

Image data is stored in two locations. The actual image data is stored in a configurable storage location such as cloud storage or a filesystem volume. The image metadata, which is exposed by the standard cluster APIs and is used to perform access control, is stored as standard API resources, specifically images and imagestreams.

3.2. Third party registries

Azure Red Hat OpenShift can create containers using images from third party registries, but it is unlikely that these registries offer the same image notification support as the integrated Azure Red Hat OpenShift registry. In this situation Azure Red Hat OpenShift will fetch tags from the remote registry upon imagestream creation.

Refreshing the fetched tags is as simple as running oc import-image <stream>. When new images are detected, the previously-described build and deployment reactions occur.

3.2.1. Authentication

Azure Red Hat OpenShift can communicate with registries to access private image repositories using credentials supplied by the user. This allows Azure Red Hat OpenShift to push and pull images to and from private repositories.

3.3. Red Hat Quay registries

If you need an enterprise-quality container image registry, Red Hat Quay is available both as a hosted service and as software you can install in your own data center or cloud environment. Advanced registry features in Red Hat Quay include geo-replication, image scanning, and the ability to roll back images.

Visit the Quay.io site to set up your own hosted Quay registry account. After that, follow the Quay Tutorial to log in to the Quay registry and start managing your images.

You can access your Red Hat Quay registry from Azure Red Hat OpenShift like any remote container image registry.

3.4. Authentication enabled Red Hat registry

All container images available through the Red Hat Container Catalog are hosted on an image registry, registry.redhat.io.

The registry, registry.redhat.io, requires authentication for access to images and hosted content on Azure Red Hat OpenShift. Following the move to the new registry, the existing registry will be available for a period of time.

Note

Azure Red Hat OpenShift pulls images from registry.redhat.io, so you must configure your cluster to use it.

The new registry uses standard OAuth mechanisms for authentication, with the following methods:

  • Authentication token. Tokens, which are generated by administrators, are service accounts that give systems the ability to authenticate against the container image registry. Service accounts are not affected by changes in user accounts, so the token authentication method is reliable and resilient. This is the only supported authentication option for production clusters.
  • Web username and password. This is the standard set of credentials you use to log in to resources such as access.redhat.com. While it is possible to use this authentication method with Azure Red Hat OpenShift, it is not supported for production deployments. Restrict this authentication method to stand-alone projects outside Azure Red Hat OpenShift.

You can use podman login with your credentials, either username and password or authentication token, to access content on the new registry.

All imagestreams point to the new registry. Because the registry requires authentication for access, the Samples Operator creates the samples-registry-credentials secret.

You must place your credentials in two places:

  • OpenShift namespace. Your credentials must exist in the OpenShift namespace so that the imagestreams in the OpenShift namespace can import.
  • Your host. Your credentials must exist on your host because Kubernetes uses the credentials from your host when it goes to pull images.

Chapter 4. Accessing the registry

Use the following sections for instructions on accessing the registry, including viewing logs and metrics, as well as securing and exposing the registry.

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

Prerequisites

  • You must have configured an identity provider (IDP).
  • For pulling images, for example when using the podman pull command, the user must have the registry-viewer role. To add this role:

    $ oc policy add-role-to-user registry-viewer <user_name>
  • For writing or pushing images, for example when using the podman push command, the user must have the registry-editor role. To add this role:

    $ oc policy add-role-to-user registry-editor <user_name>

4.1. Accessing registry directly from the cluster

You can access the registry from inside the cluster.

Procedure

Access the registry from the cluster by using internal routes:

  1. Log in to the container image registry by using your access token:

    $ podman login -u $(oc whoami) -p $(oc whoami -t) $(oc -n openshift-image-registry get route default-route -o jsonpath='{.spec.host}')

    You should see a message confirming login, such as:

    Login Succeeded!
    Note

    You can pass any value for the user name; the token contains all necessary information. Passing a user name that contains colons will result in a login failure.

    Since the Image Registry Operator creates the route, it will likely be similar to default-route-openshift-image-registry.<cluster_name>.

  2. Perform podman pull and podman push operations against your registry:

    Important

    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, use:

    ComponentValue

    <project>

    openshift

    <image>

    image

    <tag>

    omitted (defaults to latest)

    1. Pull an arbitrary image:

      $ podman pull name.io/image
    2. Tag the new image with the form <registry_url>:<project>/<image>. The project name must appear in this pull specification for Azure Red Hat OpenShift to correctly place and later access the image in the registry:

      $ podman tag name.io/image $(oc -n openshift-image-registry get route default-route -o jsonpath='{.spec.host}')/openshift/image
      Note

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

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

      $ podman push $(oc -n openshift-image-registry get route default-route -o jsonpath='{.spec.host}')/openshift/image

4.2. Viewing the registry’s contents

As an administrator, you can view your registry’s contents.

Prerequisites

  • Log in as administrator.

Procedure

  1. Check the pods under project openshift-image-registry:

    # oc get pods
    NAME READY STATUS RESTARTS AGE
    cluster-image-registry-operator-764bd7f846-qqtpb 1/1 Running 0 78m
    image-registry-79fb4469f6-llrln 1/1 Running 0 77m
    node-ca-hjksc 1/1 Running 0 73m
    node-ca-tftj6 1/1 Running 0 77m
    node-ca-wb6ht 1/1 Running 0 77m
    node-ca-zvt9q 1/1 Running 0 74m

4.3. Viewing registry logs

You can view the logs for the registry by using the oc logs command.

Procedure

  1. Use the oc logs command with deployments to view the logs for the container image registry:

    $ oc logs deployments/image-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" instance.id=9ed6c43d-23ee-453f-9a4b-031fea646002
    2015-05-01T19:48:36.303422845Z time="2015-05-01T19:48:36Z" level=info msg="using inmemory layerinfo cache" instance.id=9ed6c43d-23ee-453f-9a4b-031fea646002
    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" instance.id=9ed6c43d-23ee-453f-9a4b-031fea646002

4.4. 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.

Procedure

There are two ways in which you can access the metrics, running a metrics query or using the cluster role.

Metrics query

  1. Run a metrics query, for example:

    $ curl --insecure -s -u <user>:<secret> \ 1
        https://image-registry.openshift-image-registry.svc:5000/extensions/v2/metrics | grep imageregistry | head -n 20
    # HELP imageregistry_build_info A metric with a constant '1' value labeled by major, minor, git commit & git version from which the image registry was built.
    # TYPE imageregistry_build_info gauge
    imageregistry_build_info{gitCommit="9f72191",gitVersion="v3.11.0+9f72191-135-dirty",major="3",minor="11+"} 1
    # HELP imageregistry_digest_cache_requests_total Total number of requests without scope to the digest cache.
    # TYPE imageregistry_digest_cache_requests_total counter
    imageregistry_digest_cache_requests_total{type="Hit"} 5
    imageregistry_digest_cache_requests_total{type="Miss"} 24
    # HELP imageregistry_digest_cache_scoped_requests_total Total number of scoped requests to the digest cache.
    # TYPE imageregistry_digest_cache_scoped_requests_total counter
    imageregistry_digest_cache_scoped_requests_total{type="Hit"} 33
    imageregistry_digest_cache_scoped_requests_total{type="Miss"} 44
    # HELP imageregistry_http_in_flight_requests A gauge of requests currently being served by the registry.
    # TYPE imageregistry_http_in_flight_requests gauge
    imageregistry_http_in_flight_requests 1
    # HELP imageregistry_http_request_duration_seconds A histogram of latencies for requests to the registry.
    # TYPE imageregistry_http_request_duration_seconds summary
    imageregistry_http_request_duration_seconds{method="get",quantile="0.5"} 0.01296087
    imageregistry_http_request_duration_seconds{method="get",quantile="0.9"} 0.014847248
    imageregistry_http_request_duration_seconds{method="get",quantile="0.99"} 0.015981195
    imageregistry_http_request_duration_seconds_sum{method="get"} 12.260727916000022
    1
    <user> can be arbitrary, but <secret> must match the value specified in the registry configuration.

Cluster role

  1. Create a cluster role if you do not already have one to access the metrics:

    $ cat <<EOF |
    apiVersion: rbac.authorization.k8s.io/v1
    kind: ClusterRole
    metadata:
      name: prometheus-scraper
    rules:
    - apiGroups:
      - image.openshift.io
      resources:
      - registry/metrics
      verbs:
      - get
    EOF
    $ oc create -f -
  2. Add this role to a user, run the following command:

    $ oc adm policy add-cluster-role-to-user prometheus-scraper <username>
  3. Access the metrics using cluster role. The part of the configuration file responsible for metrics should look like this:

    openshift:
      version: 1.0
      metrics:
        enabled: true
    ...

Additional resources

Chapter 5. Exposing the registry

By default, the Azure Red Hat OpenShift registry is secured during cluster installation so that it serves traffic through TLS. Unlike previous versions of Azure Red Hat OpenShift, the registry is not exposed outside of the cluster at the time of installation.

5.1. Exposing a secure registry manually

Instead of logging in to the Azure Red Hat OpenShift registry from within the cluster, you can gain external access to it by exposing it with a route. This allows you to log in to the registry from outside the cluster using the route address, and to tag and push images using the route host.

Prerequisites:

  • The following prerequisites are automatically performed:

    • Deploy the Registry Operator.
    • Deploy the Ingress Operator.

Procedure

You can expose the route by using DefaultRoute parameter in the configs.imageregistry.operator.openshift.io resource or by using custom routes.

To expose the registry using DefaultRoute:

  1. Set DefaultRoute to True:

    $ oc patch configs.imageregistry.operator.openshift.io/cluster --patch '{"spec":{"defaultRoute":true}}' --type=merge
  2. Log in with Podman:

    $ HOST=$(oc get route default-route -n openshift-image-registry --template='{{ .spec.host }}')
    $ podman login -u $(oc whoami) -p $(oc whoami -t) --tls-verify=false $HOST 1
    1
    --tls-verify=false is needed if the cluster’s default certificate for routes is untrusted. You can set a custom, trusted certificate as the default certificate with the Ingress Operator.

To expose the registry using custom routes:

  1. Create a secret with your route’s TLS keys:

    $ oc create secret tls public-route-tls \
        -n image-registry \
        --cert=</path/to/tls.crt> \
        --key=</path/to/tls.key>

    This step is optional. If you do not create a secret, the route uses the default TLS configuration from the Ingress Operator.

  2. On the Registry Operator:

    spec:
      routes:
        - name: public-routes
          hostname: myregistry.mycorp.organization
          secretName: public-route-tls
    ...

    Only set secretName if you are providing a custom TLS configuration for the registry’s route.

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