To configure GCR first select Google Container Registry from the new registry drop down and then provide the following
- Registry Name - A unique name for this configuration
- Key File - The contents of a JSON key file. See bellow for instructions
The JSON key file holds your credentials for a given Service Account. To generate your key file follow these instructions
- Go to your Cloud Platform Console Credentials page
- Select the project that you're creating credentials for.
- To set up a new service account, click Create credentials and then select Service account key.
- Choose the service account to use for the key.
- Choose to download the service account's public/private key as a JSON file.
You can find the complete guide here.