Private registry and not authenticating


Attempting to use the private registry capability for setup_remote_docker. Relevant portion of config.yml looks like this:

version: 2

      - image:
          username: $QU
          password: $QA

but this fails with the following error:

Starting container
image cache not found on this host, downloading
Error response from daemon: unauthorized: access to the requested resource is not authorized

(I’ve substituted for actual org name obviously)

but the credentials are correct and docker login works fine. Tried providing those env variables both in the ‘project’ definition within circleci as well as via config.yml but it doesn’t change the outcome. Are there any other resources for understanding using circleci with private registries (quay in particular)