Pulp registry can accept basic auth credentials only in plain text. Nowadays these credentials very often are based64 encoded and stored in the auth.json file. Pulp Registry is not able to use already encoded credentials, as Some registries require a result it produces bas user experience where users are forces to decode secret pull provided during the credentials manually and provide them to Pulp Registry. pull of the content.
Secret pull is a base64 encoded username+password. It can contain credentials to multiple registries.
Add an option called `--secret-pull` which will accept the secret pull info in the json format. Pulp will parse it and extract the `auth` part which will be used in the Basic auth headers and sent to the registry.