Comment 1 for bug 1814633

For info; the GCP provider for juju doesn't seem to follow the standard pattern of simplestreams.

Instead, environ_broker.go creates the image path by appending ubuntuImageBasePath + spec.Image.Id

ubuntuImageBasePath is hardcoded in gce.go to projects/ubuntu-os-cloud/global/images/

Image.Id appears to come from simplestreams download but I can't see where just yet.

We would happily provide a local simplestreams json to point to our own custom GCP image, but because the ubuntuImageBasePath is hardcoded in juju, we can't tell juju to use any of our own images.