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Understanding disconnected installation mirroring

You can use a mirror registry for disconnected installations and to ensure that your clusters only use container images that satisfy your organization’s controls on external content. Before you install a cluster on infrastructure that you provision in a disconnected environment, you must mirror the required container images into that environment. To mirror container images, you must have a registry for mirroring.

Mirroring images for a disconnected installation through the Agent-based Installer

You can use one of the following procedures to mirror your OpenShift Container Platform image repository to your mirror registry:

About mirroring the OpenShift Container Platform image repository for a disconnected registry

To use mirror images for a disconnected installation with the Agent-based Installer, you must modify the install-config.yaml file.

You can mirror the release image by using the output of either the oc adm release mirror or oc mirror command. This is dependent on which command you used to set up the mirror registry.

The following example shows the output of the oc adm release mirror command.

$ oc adm release mirror
Example output
To use the new mirrored repository to install, add the following
section to the install-config.yaml:

imageContentSources:

mirrors:
virthost.ostest.test.metalkube.org:5000/localimages/local-release-image
source: quay.io/openshift-release-dev/ocp-v4.0-art-dev
mirrors:
virthost.ostest.test.metalkube.org:5000/localimages/local-release-image
source: registry.ci.openshift.org/ocp/release

The following example shows part of the imageContentSourcePolicy.yaml file generated by the oc-mirror plugin. The file can be found in the results directory, for example oc-mirror-workspace/results-1682697932/.

Example imageContentSourcePolicy.yaml file
spec:
  repositoryDigestMirrors:
  - mirrors:
    - virthost.ostest.test.metalkube.org:5000/openshift/release
    source: quay.io/openshift-release-dev/ocp-v4.0-art-dev
  - mirrors:
    - virthost.ostest.test.metalkube.org:5000/openshift/release-images
    source: quay.io/openshift-release-dev/ocp-release

Configuring the Agent-based Installer to use mirrored images

You must use the output of either the oc adm release mirror command or the oc-mirror plugin to configure the Agent-based Installer to use mirrored images.

Procedure

  1. If you used the oc-mirror plugin to mirror your release images:

    1. Open the imageContentSourcePolicy.yaml located in the results directory, for example oc-mirror-workspace/results-1682697932/.

    2. Copy the text in the repositoryDigestMirrors section of the yaml file.

  2. If you used the oc adm release mirror command to mirror your release images:

    • Copy the text in the imageContentSources section of the command output.

  3. Paste the copied text into the imageContentSources field of the install-config.yaml file.

  4. Add the certificate file used for the mirror registry to the additionalTrustBundle field of the yaml file.

    The value must be the contents of the certificate file that you used for your mirror registry. The certificate file can be an existing, trusted certificate authority, or the self-signed certificate that you generated for the mirror registry.
    Example install-config.yaml file
      additionalTrustBundle: |
    -----BEGIN CERTIFICATE-----
    ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
    -----END CERTIFICATE-----

  5. If you are using GitOps ZTP manifests: add the registries.conf and ca-bundle.crt files to the mirror path to add the mirror configuration in the agent ISO image.

    You can create the registries.conf file from the output of either the oc adm release mirror command or the oc mirror plugin. The format of the /etc/containers/registries.conf file has changed. It is now version 2 and in TOML format.
    Example registries.conf file
    [[registry]]
location = "registry.ci.openshift.org/ocp/release" mirror-by-digest-only = true

[[registry.mirror]] location = "virthost.ostest.test.metalkube.org:5000/localimages/local-release-image"

[[registry]]
location = "quay.io/openshift-release-dev/ocp-v4.0-art-dev" mirror-by-digest-only = true

[[registry.mirror]] location = "virthost.ostest.test.metalkube.org:5000/localimages/local-release-image"