By default, at least in Ubuntu, Docker container logs will grow indefinitely (in my case up to 412 GB, thus filling up my hard drive).

To prevent this, you can create a /etc/docker/daemon.json file with the following configuration:

{
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "10m",
    "max-file": "3"
  }
}

Don't forget to restart the Docker service afterwards, and in my case I had to do the following as well:

$ sudo systemctl restart docker
$ docker-compose down   # this destroyed all my nice containers, but without it, they wouldn't accept the log config (maybe there's a better solution?)
$ docker-compose up -d

Finally, to check that the config was successful, for any of the containers that are running you can do this: (remember to replace the container ID)

$ docker inspect 3fa6f8fd01d6 | jq '.[0].HostConfig.LogConfig'
{
  "Type": "json-file",
  "Config": {
    "max-file": "3",
    "max-size": "10m"
  }
}
Final thoughts

Why would the default Docker configuration not have a log size limit‽ This makes zero sense to me.

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