Installing the base image, if necessary

The Resource Manager update script requires content from the base image of the current version. If you have flattened the layers of the base image since installation, the image may not have the expected label, and the upgrade script will not find it.

Follow these steps to determine whether the base image is present, and to download and install it, if necessary:

Log in to the Control Center host as root or as a user with superuser privileges.
Search for the base image.
```
docker images | grep -E 'zenoss/resmgr'
```
- If the base image is present, the command returns a result. Continue to the next upgrade procedure.
- If the base image is absent, the command returns no result. Follow the steps in Downloading Resource Manager image files to download the base image of the current version. Then, import the image.