katcp_prometheus_bridge

Connects to a katcp interface and publishes sensor values as Prometheus Gauge metrics.

Python 3.7+ is required.

Caveats

Prometheus flattens metrics into a untyped time series, but katcp has several data types.

katcp data types are handled as follows:

• string and address
  • By default they are ignored.
  • There is a workaround for these. Sensor values are are added to a list as they are retrieved. An index into that list for the current setting is returned. A user may be able to infer the meaning of the index.
  • Enable it by adding the commandline option --workaround_strings or an environment variable named WORKAROUND_STRINGS
  • Usage of this option is however discouraged.
• bool
  • 0.0 is False
  • 1.0 is True
• discrete
  • When the sensor is added we know what the possible values are. An index into that list for the current value is returned.
  • The options are displayed in the HELP string.
• float
  • Returned as is.
• int
  • Retuned as its float value.

Run in docker

• Check out the repo (or just the Dockerfile)
• Build the container
  • docker build -t katcp_prometheus_bridge .
• Run the container
  • docker run -e "KATCP_HOST=<KATCP_HOST>" -e "KATCP_PORT=<KATCP_PORT>" -p 8080:8080 katcp_prometheus_bridge
• Browse to http://0.0.0.0:8080/metrics

TODO

• Expand tests
• Make sure interface changed from katcp is handled correctly
• Exit the asyncio loop cleanly upon exit
• Maybe add a mechanism to list which sensors to watch.