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Image Registry for Embedded Clusters

The Replicated kURL installer includes the kURL Registry add-on, which can be used to host application images on embedded clusters.

For air gap installations, the embedded kURL registry is automatically used to host all application images.

For more information about the kURL Registry add-on, see Registry Add-On in the kURL documentation.

Enable and Disable Image Garbage Collection

Introduced in KOTS 1.48.0

With every application update, new images are pushed to this registry. To keep the registry from running out of storage, images that are no longer used are automatically deleted from the registry.

This feature is currently only supported in embedded clusters when using the Registry add-on. Image garbage collection is enabled by default. To disable this feature, execute the following command in the cluster:

kubectl patch configmaps kotsadm-confg --type merge -p "{\"data\":{\"enable-image-deletion\":\"false\"}}"

To enable garbage collection again, execute the following command:

kubectl patch configmaps kotsadm-confg --type merge -p "{\"data\":{\"enable-image-deletion\":\"true\"}}"

Garbage collection is triggered automatically when a new application version is deployed. The admin-console garbage-collect-images command can be used to trigger it manually. For more information, see admin-console garbage-collect-images in the kots CLI documentation.

Restoring Deleted Images

Deleted images can be reloaded from air gap bundles using the admin-console push-images command. For more information, see admin-console push-images in the kots CLI documentation.

For an example of using the admin-console push-images command, see Air Gap Installation in Existing Clusters.

The registry address and namespace can be found on the Registry Settings page in the Replicated admin console. The registry username and password can be found in the registry-creds secret in the default namespace.

Limitations

Currently the image garbage collection feature has following limitations:

Optional Components

Some applications define Kubernetes resources that can be enabled or disabled dynamically. For example, template functions can be used to conditionally deploy a StatefulSet based on configuration from the user. If a resource is disabled and no longer deployed, its images can be included in the garbage collection.

To prevent this from happening, include the optional images in the additionalImages list of the Application custom resource. For more information, see additionalImages in Application.

Shared Image Registries

The image garbage collection process assumes that the registry is not shared with any other instances of Replicated KOTS, nor shared with any external applications. If the embedded registry is used by another external application, disable this feature to prevent image loss.

Customer Supplied Registries

This feature is currently only supported when used with the embedded kURL registry. If the KOTS instance is configured to use a different registry, disable this feature to prevent image loss.

Application Rollbacks

Currently image garbage collection has no effect when the allowRollback field in the application.yaml file is set to true. For more information, see Application.