Logrotate for Docker container

It's a best practice to log the Docker container output to /dev/stdout and /dev/stderr. But you should not forget to enable a Logrotate for your Docker container log files. The Docker container log file is saved in /var/lib/docker/containers/[CONTAINER ID]/[CONTAINER_ID]-json.log. You can use another service like fluentd or the ELK (Elasticsearch, Logstash, Kibana) stack but this is the simplest and quickest way to ensure to not run out of disk space.

Enable Logrotate

Since Docker 1.8 you can use the build-in logrotate functionality.

To create a new Logrotate config file for your Docker containers simply create a new file in the Logrotate folder /etc/logrotate.d/docker-container and put the following lines to it:

/var/lib/docker/containers/*/*.log {
  rotate 7
  daily
  compress
  size=1M
  missingok
  delaycompress
  copytruncate
}

Once you have configured Logrotate for you Docker container you can test it with logrotate -fv /etc/logrotate.d/docker-container. You should get some output and a new log file with suffix [CONTAINER ID]-json.log.1 should be created. This file is compressed in next rotation cycle.

Conclusion

Log rotation for Docker container is easy with Logrotate. For production use cases, you should use a logging driver like fluentd or setup your own ELK stack. Which Docker logging driver do you use?

Do you know the performance differences of the Docker filesystem driver? Learn
how to optimize your Docker performance with OverlayFS.

Article picture: Port-Saint-Louis-du-Rhône,FR13 by Jean-Louis Zimmermann under CC BY 2.0

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