* Alerting: Send alerts to external Alertmanager(s)
Within this PR we're adding support for registering or unregistering
sending to a set of external alertmanagers. A few of the things that are
going are:
- Introduce a new table to hold "admin" (either org or global)
configuration we can change at runtime.
- A new periodic check that polls for this configuration and adjusts the
"senders" accordingly.
- Introduces a new concept of "senders" that are responsible for
shipping the alerts to the external Alertmanager(s). In a nutshell,
this is the Prometheus notifier (the one in charge of sending the alert)
mapped to a multi-tenant map.
There are a few code movements here and there but those are minor, I
tried to keep things intact as much as possible so that we could have an
easier diff.
* Alerting: Cleanup and move legacy to a legacy file
A quick cleanup of the ngalert/api directory, optimising for an easy
removal of what is will be considered legacy at some point. A quick
summary of what's done is:
- Add a prefix `generated` prefix to files that are auto-generated by
our swagger definitions.
- Create a legacy file to place all the legacy API routes implementation
and helpers. Deleting files that where no longer needed after this
move.
- Rename the `lotex` file to `lotex_ruler`
- Adding a couple of comments here and there.
With this, I hope to organise our code in this directory a bit better
given there's a lot going on.
gotjosh
Owen Diehl