Add support for log.level in config/environment

[dsvensson]

What did you do?

Started prometheus under docker-compose.

What did you expect to see?

Nothing.

What did you see instead? Under which circumstances?

Lots of log INFO's that I want to hide.

Environment

prom/prometheus docker container.

• System information:

  docker

• Prometheus version:

  2.0.0-rc2

• Logs:

prometheus_1  | level=info ts=2017-10-31T22:19:06.761671514Z caller=main.go:215 msg="Starting Prometheus" version="(version=2.0.0-rc.2, branch=master, revision=3701a827cf5da595bd2366dad6e1b3c979a1009c)"

Turns out Prometheus doesn't support setting log.level in the config file, which requires copying the whole ENTRYPOINT/CMD from the prom/prometheus Dockerfile:

ENTRYPOINT [ "/bin/prometheus" ]
CMD        [ "--config.file=/etc/prometheus/prometheus.yml", \
             "--storage.tsdb.path=/prometheus", \
             "--web.console.libraries=/usr/share/prometheus/console_libraries", \
             "--web.console.templates=/usr/share/prometheus/consoles" ]

...and pasteing into docker-compose.yml, with --log.level=warn added:

    prometheus:
      image: prom/prometheus:master
      entrypoint:
        - "/bin/prometheus"
        - "--log.level=warn"
        - "--config.file=/etc/prometheus/prometheus.yml"
        - "--storage.tsdb.path=/prometheus"
        - "--web.console.libraries=/usr/share/prometheus/console_libraries"
        - "--web.console.templates=/usr/share/prometheus/consoles"
      volumes:
        - ./prometheus.yml:/etc/prometheus/prometheus.yml

Ideally this would be possible to either override via environment variables, or the config file.

Here is how log.level can be overridden for Grafana in docker-compose.yml:

    grafana:
      image: grafana/grafana
      environment:
        GF_LOG_CONSOLE_LEVEL: warn
      depends_on:
        - prometheus
      links:
        - prometheus
      ports:
        - 3000:3000

[brian-brazil]

For Prometheus we only offer one way to configure a given option to keep things simple. It is presumed that you have a configuration management system which handles things like this, and multiple configuration sources with potentially conflicting information does not help you.

[dsvensson]

No need to change Prometheus. This can be handled via a wrapper script in the default Dockerfile.

[brian-brazil]

If you want a wrapper, you can add it within your own configuration management setup.

[dsvensson]

Yes, ofc, but that would benefit few. I filed #3385 instead that leaves out any Prometheus modifications.

[lock]

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