_wal-g_ can send StatsD metrics when it completes an upload/backup/etc.
task. Using the `statsd_exporter`, we can capture these metrics and
make them available to Victoria Metrics.
Since LAN clients have IPv6 addresses now, some may try to connect to
the database over IPv6, so we need to allow this in the host-based
authentication rules.
The [postgres-exporter][0] exposes PostgreSQL server statistics to
Prometheus. It connects to a specified PostgreSQL server (in this
case, a server on the local machine via UNIX socket) and collects data
from the `pg_stat_activity`, et al. views. It needs the `pg_monitor`
role in order to be allowed to read the relevant metrics.
Since we're setting up the exporter to connect via UNIX socket, it needs
a dedicated OS user to match the PostgreSQL user in order to
authenticate via the _peer_ method.
[0]: https://github.com/prometheus-community/postgres_exporter/
By default, WAL-G tries to connect to the PostgreSQL server via TCP
socket on the loopback interface. Our HBA configuration requires
certificate authentication for TCP sockets, so we need to configure
WAL-G to use the UNIX socket.
All data have been migrated from the PostgreSQL server in Kubernetes and
the three applications that used it (Firefly-III, Authelia, and Home
Assistant) have been updated to point to the new server.
To avoid comingling the backups from the old server with those from the
new server, we're reconfiguring WAL-G to push and pull from a new S3
prefix.
I am going to use the *postgresql* group for the dedicated database
servers. The configuration for those machines will be quite a bit
different than for the one existing machine that is a member of that
group already: the Nextcloud server. Rather than undefine/override all
the group-level settings at the host level, I have removed the Nextcloud
server from the *postgresql* group, and updated the `nextcloud.yml`
playbook to apply the *postgresql-server* role itself.
Eventually, I want to move the Nextcloud database to the central
database servers. At that point, I will remove the *postgresql-server*
role from the `nextcloud.yml` playbook.
Dustin