[FLOC-3983] Acceptance tests prep for node shutdown

[itamarst]

When a node is shutdown and later started its public IP may have changed. We want to have an acceptance test that shuts down a node, to test moving datasets off dead nodes. We can therefore not rely on a fixed public IP for all tests.

Did so by trusting Flocker's reported IPs for nodes by default. However, if the backend provides ICloudAPI we use that to figure out public IP for each node.

[sarum90]

nit: extra . also

``unicode``

[sarum90]

Good stuff, looks like a nice way to work around the problem.

Although, it seems that the loopback tests are currently failing with this change :(

I'd really like to see a slightly better interface for listing the live nodes (specifically returning something that is not a map from compute_instance_id to list of ip addresses). I would be much more happy about maintaining something that looked like that long term.

For now I think I'm going to ask for a second review after things are patched up. Should be a quick second review though, just to verify the fix for the presently failing loopback acceptance tests and look at the new interface.

[itamarst]

The tests are failing because loopback backend doesn't support ICloudAPI. I think the way to solve this is to restore the env variables for public IP, and use them if ICloudAPI is not available on the backend. Since ICloudAPI isn't available the shutdown test won't run, so the public IP won't be invalidated and using the env variables will therefore be OK.