PowerDNS Prometheus Exporter

An alternate spin on a PowerDNS exporter which works using metrics read from the PowerDNS control-socket, rather than the REST API. This makes it compatible with older versions of PowerDNS, and avoids the need to turn on or secure the REST API if it is not needed.

Since older versions of powerDNS blocked the serving loop while metrics are being read, rate-limiting functionality is included and turned ON by default - that is, multiple prometheus scrapes will be limited by a cool-down period (by default 10 seconds).

If you are using a newer version (PowerDNS 4+) then this problem does not apply as metric scrapes are atomic, and you can disable it for more precise metrics.

CLI Options

• web.listen-address Default :9120

• web.telemetry-path Default /metrics. Web path to expose Prometheus metrics at.

• collector.powerdns.socket Default authoritative:unix:/var/run/powerdns.controlsocket. Comma separed list of paths to PowerDNS instances to monitor. Must be prefixed with the type of server being monitored, either authoritative or recursor.

• collector.powerdns.local-socket.mode Default 640. Modifies permissions on the local socket used to receive responses from the recursor

• collector.tempdir.prefix Default is blank. If specified modifies the prefix used for where response sockets are created for talking to a recursor with unixgrams. This should be set if you are trying to monitor with pdns_exporter in a Docker container, and should be set to a shared volume between the exporter container and the pdns_recursor container.

• collector.rate-limit.enable Default true. If enabled, metrics will be cached and only re-collected whenadter collector.rate-limit.min-cooldown seconds.

• collector.rate-limit.min-cooldown Default 10s. Minimum time between allowing scrapes of the server.

• collector.timeout Default 1s. Maximum time to wait for a PowerDNS control socket to respond.

Monitoring pdns_recursor

pdns_recursor uses a unixgram rather then unix control socket. To monitor a pdns_recursor process use the following settings:

$ ./pdns_exporter.x86_64 -collector.powerdns.socket=recursor:unixgram:/run/pdns_recursor.controlsocket

The process also needs to run as the same user as pdns itself, otherwise control socket replies won't work. The -collector.powerdns.local-socket.mode option can help in this regard by altering the permissions on the launched process to be looser. The default is 640.