This commit removes the metrics from the compat package
in favour of the existing logging and the additional tools
at hand, such as amtool, to validate Alertmanager configurations.
Due to the global nature of the compat package, a consequence
of config.Load, these metrics have proven to be less useful
in practice than expected, both in Alertmanager and other projects
such as Mimir.
There are a number of reasons for this:
1. Because the compat package is global, these metrics cannot be
reset each time config.Load is called, as in multi-tenant
projects like Mimir loading a config for one tenant would reset
the metrics for all tenants. This is also the reason the metrics
are counters and not gauges.
2. Since the metrics are counters, it is difficult to create
meaningful dashboards for Alertmanager as, unlike in Mimir,
configurations are not reloaded at fixed intervals, and as such,
operators cannot use rate to track configuration changes
over time.
In Alertmanager, there are much better tools available to validate
that an Alertmanager configuration is compatible with the UTF-8
parser, including both the existing logging from Alertmanager
server and amtool check-config.
In other projects like Mimir, we can track configurations for
individual tenants using log aggregation and storage systems
such as Loki. This gives operators far more information than
what is possible with the metrics, including the timestamp,
input and ID of tenant configurations that are incompatible
or have disagreement.
Signed-off-by: George Robinson <george.robinson@grafana.com>