Prepare a host

If you are in an air-gapped environment, you must be able to connect a host to the internet and mirror registry for connected mirroring or mirror images to file system which can be brought to a restricted environment for disconnected mirroring. For information on the latest supported operating systems, see ibm-pak plugin install documentation.

The following table explains the software requirements for mirroring the IBM Cloud Pak images:

Table 1. software requirements for mirroring the IBM Cloud Pak images
Software	Purpose
Docker	Container management
Podman	Container management
Red Hat OpenShift CLI (oc)	Red Hat OpenShift Container Platform administration

Complete the following steps on your host:

Install Docker or Podman.
To install Docker (for example, on Red Hat® Enterprise Linux®), run the following commands:
Note: If you are installing as a non-root user you must use sudo. For more information, refer to the Podman or Docker documentation for installing as a non-root user.
```
yum check-update
yum install docker
```
To install Podman, see Podman Installation Instructions.
Install the oc Red Hat® OpenShift® Container Platform CLI tool.
Download and install the most recent version of IBM Catalog Management Plug-in for IBM Cloud Paks from the IBM/ibm-pak. Extract the binary file by entering the following command:
```
tar -xf oc-ibm_pak-linux-amd64.tar.gz
```
Run the following command to move the file to the /usr/local/bin directory:
Note: If you are installing as a non-root user you must use sudo. For more information, refer to the Podman or Docker documentation for installing as a non-root user.
```
mv oc-ibm_pak-linux-amd64 /usr/local/bin/oc-ibm_pak
```
Note: Download the plug-in based on the host operating system. You can confirm that oc ibm-pak -h is installed by running the following command:
```
oc ibm-pak --help
```
The plug-in usage is displayed.

For more information on plug-in commands, see command-help.

Your host is now configured and you are ready to mirror your images.

Creating registry namespaces

Top-level namespaces are the namespaces which appear at the root path of your private registry. For example, if your registry is hosted at myregistry.com:5000, then mynamespace in myregistry.com:5000/mynamespace is defined as a top-level namespace. There can be many top-level namespaces.

When the images are mirrored to your private registry, it is required that the top-level namespace where images are getting mirrored already exists or can be automatically created during the image push. If your registry does not allow automatic creation of top-level namespaces, you must create them manually.

When you generate mirror manifests, you can specify the top-level namespace where you want to mirror the images by setting TARGET_REGISTRY to myregistry.com:5000/mynamespace which has the benefit of needing to create only one namespace mynamespace in your registry if it does not allow automatic creation of namespaces. The top-level namespaces can also be provided in the final registry by using --final-registry.

If you do not specify your own top-level namespace, the mirroring process will use the ones which are specified by the CASEs. For example, it will try to mirror the images at myregistry.com:5000/cp etc.

So if your registry does not allow automatic creation of top-level namespaces and you are not going to use your own during generation of mirror manifests, then you must create the following namespace at the root of your registry.

There can be more top-level namespaces that you might need to create. See section on Generate mirror manifests for information on how to use the oc ibm-pak describe command to list all the top-level namespaces.