This check loads Django, and as such must be run as the zulip user.
Repeat the same pattern used elsewhere in nagios, of writing a state
file, which is read by `check_cron_file`.
Replication checks should only run on primary and replicas, not
standalone hosts; while `autovac_freeze` currently only runs on
primary hosts, it functions identically on replicas, and is fine to
run there.
Make `autovac_freeze` run on all `postgresql` hosts, and make
standalone hosts no longer `postgres_primary`, so they do not fail the
replication tests.
These style of checks just look for matching process names using
`check_remote_arg_string`, which dates to 8edbd64bb8. These were
added because the original two (`missedmessage_emails` and
`slow_queries`) did not create consumers, instead polling for events.
Switch these to checking the queue consumer counts that the
`check-rabbitmq-consumers` check is already writing out. Since the
`missedmessage_emails` was _already_ checked via the consumer check, a
duplicate is not added.
Even the `pageable_servers` group did not page for high load -- in
part because what was "high" depends on the servers. Set slightly
better limits based on server role.
`zmirror` itself was `zmirror_main` + `zmirrorp` but was unused; we
consistently just use the term `zmirror` for the non-personals server,
so use it as the hostgroup name.
The Redis nagios checks themselves are done against `redis` +
`frontends` groups, so there is no need to misleadingly place
`frontends` in the `redis` hostgroup.
5abf4dee92 made this distinction, then multitornado_frontends was
never used; the singletornado_frontends alerting worked even for the
multiple-Tornado instances.
Remove the useless and misleading distinction.