Log server v23.44.0

Assigning the log-server role to one instance in config.yml turns it into a central rsyslog destination for the cluster. TPA then automatically configures every other instance to forward its logs there — no further configuration is needed. Assign the role to only one instance per cluster: TPA won't stop you from adding it to more than one, but only the first one found is actually used, so any others just sit idle.

Centralizing logs this way means you don't have to log into each instance separately to piece together what happened during a cluster-wide event, such as a failover. It also gives you a copy of an instance's logs that survives that instance being replaced or torn down, and a single place to point log rotation, monitoring, or shipping tools at instead of configuring them on every instance.

instances:
- Name: uproar
  role:
  - primary

- Name: kinsman
  role:
  - barman
  - log-server
  - witness

What TPA configures

On every instance other than the log server, TPA forwards the following programs' log output to it over TCP port 601:

• postgres
• pgbouncer
• repmgrd
• harp-manager
• harp-proxy
• barman
• efm

If the log server is temporarily unreachable, messages are queued to local disk (up to 1 GB) and delivery is retried indefinitely once it comes back.

On the log server instance itself, TPA:

• Enables TCP syslog reception on port 601, and UDP reception on port 514 as well when failover_manager is set to efm (EFM ships its logs over UDP).
• Creates /var/log/hosts/ and writes each sending host's messages there, one file per host and program: /var/log/hosts/<hostname>/<programname>.log-YYYYMMDD.
• If the log server instance also has the barman role, tails its own /var/log/barman/barman.log into the same pipeline.

Effect on individual components

Whether log_server is set for an instance changes how some components log on it:

• Postgres keeps writing to its local log file regardless; when log_server is set, its output is additionally forwarded to the log server.
• pgbouncer logs via syslog (syslog_facility = daemon, syslog_ident = pgbouncer) instead of to /var/log/pgbouncer/pgbouncer.log.
• EFM has syslog.enabled set to true and syslog.host set to the instance's own hostname, so it logs through the local syslog daemon, which then forwards the messages on.

Overriding the default log server

If no instance has the log-server role, log_server is never set and every instance just logs locally. Once one instance has the role, every other instance defaults to sending its logs there. To route a specific instance's logs elsewhere instead, set log_server under that instance's vars:

- Name: unravel
  role:
  - replica
  vars:
    log_server: some-other-host