Working with Google Container Registry (GCR) Credentials
When working with Google Container Registry it is recommended that you use JSON keys rather than the short lived access tokens.
JSON key files are long-lived and are tightly scoped to individual projects and resources. You can read more about JSON credentials in Google’s documentation at the following URL: Google Container Registry advanced authentication
Once a JSON key file has been created with permissions to read from the container registry then the registry should be added with the username _json_key and the password should be the contents of the key file.
In the following example a file named key.json in the current directory contains the JSON key with readonly access to the my-repo repository within the my-project Google Cloud project.
anchore-cli registry add us.gcr.io _json_key "$(cat key.json)"