New azure provider ignores agent mirrors

[Curtis Hovey]

The new azure provider is not downloading agents from the azure mirror. It downloads them from streams.canonical.com. This may relate to the redefinition of regions by the new provider.

We can see at
    http://cloud-images.ubuntu.com/releases/streams/v1/index.json
the official definition of endpoints and regions. The new provider reliably provisions instances. The new provider also has special knowledge of imaages; it might not be using image streams at all.

The agent-streams at
     http://streams.canonical.com/juju/tools/streams/v1/cpc-mirrors.json
use the older endpoint that the old azure provider likes. It was assumed that the new provider wants the new endpoint. This is probably not true because Juju 1.x has handled https://core.windows.net/ and https://management.core.windows.net/ for more than a year.

A test mirror was created at
     http://people.canonical.com/~curtis/juju-dist/tools/streams/v1/cpc-mirrors.json
that defines the https://management.core.windows.net/ endpoint and uses official locations for the region and mangled format used by the new arm provider. The mirrors are ignored

The only way to use the mirrors is to force Juju to use use the mirrored agent-streams
    --config agent-streams=https://jujutools.blob.core.windows.net/juju-tools/tools

[Andrew Wilkins (axwalk)]

There's a few issues here
 - We currently don't support simplestreams for cloud-images; this is being looked at separately, currently blocked because we're not publishing streams yet.
 - To avoid filling the logs with errors, some simplestreams-related code was disabled in Azure, which led the unintended consequence of us ignoring mirrors.
 - Endpoints are different for Azure Resource Manager; and we canonicalize the region names to lowercasewithoutwhitespace, whereas the simplestreams uses Title Case.

So this would be simpler if we had image simplestreams sorted out, but I guess that's not happening just yet. I'll see what I can do for agents in the mean time.