multiple addresses in a space confuses peergrouper

From what I could see of the concrete database records, there did not appear to actually be that problem. They all seemed to have 3 concrete addresses.

Maybe the issue is with unqualified spaces (""). Where '127.0.0.1' gets tied up with other local-only addresses.

At the very least, using 127.0.0.1 is *never* the correct address to use, because the other machines will never be able to contact you on that address. So even if we selected the "" space, we still should use an address that isn't localhost.

The actual fix for them was to force the space with "mongo-space-name". Which we should make sure we can do after the fact.
Unfortunately we can't really block "juju enable-ha" if we want to use auto-detection, because the other machines won't be up for us to know how to auto-detect. Otherwise we could do something like "you must set mongo-space-name before you can enable-ha".

juju status -m controller --format=yaml

Joe is currently working on this to change the 'enable-ha' code to refuse-to-guess (and do so incorrectly), and instead make it so
a) There is a "juju controller-config ha-space=XXX" that allows administrators to set what they want
b) We will allow 'juju enable-ha' to work if there is only a single cloud-local address to use, but
c) if there is >1, refuse to guess and require the administrator to specify the space to use for enable-ha.

We need these addresses for other purposes in 2.4 which is why the name is 'ha-space' rather than something about mongo.

Mongo space name and status are are deprecated by https://github.com/juju/juju/pull/8425, and there is no longer any space auto-detection.

There are more patches to come in this same series around doing some validation earlier than in the peergrouper loop, but the a/b/c steps in John's comment above are current behaviour.