Graphite backend: Applying the globalPrefix value in legacyNamespace mode

[derpston]

It's useful to be able to specify a prefix for everything, even in legacyNamespace mode. This does that. It's a little hacky/dense, but the alternative is a lot of changes in many places, which will be a bigger diff and harder to be certain the impact is limited.

This is specifically useful for hooking up statsd to services like Hosted Graphite, but it should be more generally useful too.

I believe it also fixes a problem with the naming of the "global" prefix, where it's not actually "global". The naming implies it prefixes everything, but it only works in the new namespace mode.

Users using legacyNamespace with no globalPrefix won't be affected. Users not using legacyNamespace won't be affected. Users who are using legacyNamespace and who have a globalPrefix currently configured, but ignored, will be affected. This is likely to be a very small set of users who have tested not using the legacy namespace, but gone back to using it and not cleaned up their config. A message in the release notes should be sufficient to warn these users.

[derpston]

Looks like this caused a test to fail, I didn't catch that. I'll investigate and update this later today.

[mrtazz]

I think this change makes sense in general, however I'd much rather have a less hacky version where we correctly set the prefix when building up the strings and not run a string replace afterwards.

[derpston]

I'd prefer that too, but I think it might involve a refactor of the messy string building code. This seemed like the fastest way to make some progress, given the amount of time the clean solution will take.

Are there any plans to refactor this string building code to allow for this sort of change?

Alternatively, are there any plans to deprecate/remove the legacy namespace?

Wondering if perhaps the legacy namespace should be handled by a completely distinct backend plugin, and eliminate all those awkward string building conditionals.