Implementation of a command to fetch pre-built images from a remote registry, complementing the --push-images option already present on build-containers.
The two subcommands used together allow a stack to be deployed without needing to built its images, provided they have been already built and pushed to the specified container image registry.
This implementation simply picks the newest image with the right name and platform (matches against the platform Python is running on, so watch out for scenarios where Python is an x86 binary on M1 macs).
Reviewed-on: #768
Co-authored-by: David Boreham <david@bozemanpass.com>
Co-committed-by: David Boreham <david@bozemanpass.com>
