Logging, monitoring, diagnostics¶

To read service logs use commands usual for your distribution. E.g. on distributions using systemd-journald use command journalctl -eu knot-resolver.

logging:¶

Default: notice

Logging level notice is set after start by default, so logs from Knot Resolver should contain only couple lines a day. For debugging purposes it is possible to use the very verbose debug level, but that is generally not usable unless restricted in some way (see below).

Toggle between debug and notice log level. Use only for debugging purposes. On busy systems verbose logging can produce several MB of logs per second and will slow down operation.

In addition to levels, logging is also divided into the groups.

groups: <list of logging groups>¶

Use to turn-on debug logging for the selected groups regardless of the global log level. Other groups are logged to the log based on the initial level.

logging:
  level: notice  # other groups are logged based on this level
  groups: [manager, cache]  # enable debug logging level for manager and cache group

Less verbose logging for DNSSEC validation errors can be enabled by using DNSSEC validation failure logging module.

target: syslog|stderr|stdout¶: Knot Resolver logs to standard error stream by default, but typical systemd units change that to 'syslog'. That setting logs directly through systemd’s facilities (if available) to preserve more meta-data. Do not edit if you do not know what you are doing.

Various statistics for monitoring purposes are available in Statistics collector, including export to central systems like Graphite, Metronome, InfluxDB, or Prometheus format.

Additional monitoring and debugging methods are described below. If none of these options fits your deployment or if you have special needs you can configure your own checks and exports using Asynchronous events.