// Module included in the following assemblies:
//
// * installing/disconnected_install/installing-mirroring-disconnected.adoc
// * updating/updating_a_cluster/updating_disconnected_cluster/mirroring-image-repository.adoc

:_mod-docs-content-type: CONCEPT
[id="installation-oc-mirror-about_{context}"]
= About the oc-mirror plugin

[role="_abstract"]
You can use the oc-mirror OpenShift CLI (`oc`) plugin to mirror all required {product-title} content and other images to your mirror registry by using a single tool.

It provides the following features:

* Provides a centralized method to mirror {product-title} releases, Operators, helm charts, and other images.

* Maintains update paths for {product-title} and Operators.

* Uses a declarative image set configuration file to include only the {product-title} releases, Operators, and images that your cluster needs.

* Performs incremental mirroring, which reduces the size of future image sets.

* Prunes images from the target mirror registry that were excluded from the image set configuration since the previous execution.

* Optionally generates supporting artifacts for OpenShift Update Service (OSUS) usage.

When using the oc-mirror plugin, you specify which content to mirror in an image set configuration file. In this YAML file, you can fine-tune the configuration to only include the {product-title} releases and Operators that your cluster needs. This reduces the amount of data that you need to download and transfer. The oc-mirror plugin can also mirror arbitrary helm charts and additional container images to assist users in seamlessly synchronizing their workloads onto mirror registries.

The first time you run the oc-mirror plugin, it populates your mirror registry with the required content to perform your disconnected cluster installation or update. In order for your disconnected cluster to continue receiving updates, you must keep your mirror registry updated. To update your mirror registry, you run the oc-mirror plugin using the same configuration as the first time you ran it. The oc-mirror plugin references the metadata from the storage backend and only downloads what has been released since the last time you ran the tool. This provides update paths for {product-title} and Operators and performs dependency resolution as required.

[id="installation-oc-mirror-workflow_{context}"]
== High level workflow
The following steps outline the high-level workflow on how to use the oc-mirror plugin to mirror images to a mirror registry:

. Create an image set configuration file.

. Mirror the image set to the target mirror registry by using one of the following methods:

** Mirror an image set directly to the target mirror registry.

** Mirror an image set to disk, transfer the image set to the target environment, then upload the image set to the target mirror registry.

. Configure your cluster to use the resources generated by the oc-mirror plugin.

. Repeat these steps to update your target mirror registry as necessary.

[IMPORTANT]
====
When using the oc-mirror CLI plugin to populate a mirror registry, any further updates to the target mirror registry must be made by using the oc-mirror plugin.
====
