Comment 1 for bug 1411574

Following an ad-hoc troubleshooting session on #juju. So far it seems the easiest workaround is to add these lines in the generated environments.yaml:

(for 1.20x)
tools-metadata-url: https://streams.canonical.com/juju/tools
image-metadata-url: http://cloud-images.ubuntu.com/releases

(for 1.21+)
agent-metadata-url: https://streams.canonical.com/juju/tools
image-metadata-url: http://cloud-images.ubuntu.com/releases

Then quickstart can run $ juju metadata validate-tools and $ juju metadata validate-images to ensure those will work before attempting to bootstrap.