[SOLVED] Docker Service not starting when trying to set max-size in /etc/docker/daemon.json

Docker Service not starting when trying to set max-size in /etc/docker/daemon.json

The docker service does not seem to recognize the max-size log-opts setting in the daemon.json file and thus fails to start.

/etc/docker/daemon.json

{
    "log-driver": "syslog",
    "log-opts": {
        "tag": "docker/{{.Name}}",
        "syslog-address": "unixgram:///dev/log",
        "max-size": "1g",
        "max-file": "3"
    }
}

Output when attempting to start the docker in debug

sudo dockerd --debug

INFO[2024-01-08T21:26:17.680158874Z] Starting up
DEBU[2024-01-08T21:26:17.680948989Z] Listener created for HTTP on unix (/var/run/docker.sock)
DEBU[2024-01-08T21:26:17.682318614Z] Golang's threads limit set to 56700
DEBU[2024-01-08T21:26:17.682822324Z] metrics API listening on /var/run/docker/metrics.sock
DEBU[2024-01-08T21:26:17.691143680Z] processing event stream                       module=libcontainerd namespace=plugins.moby
DEBU[2024-01-08T21:26:17.691567388Z] Cleaning up old mountid : start.
failed to start daemon: failed to set log opts: unknown log opt 'max-size' for syslog log driver

Not sure what i could be missing here, as this is a valid flag according to the logging driver doc, Configure logging drivers

Docker version 24.0.7, build afdd53b

Removing the "max-size" and "max-file" key value pairs from the daemon.json file works just fine and docker is able to start normally.

Solution

Options are specific to each driver, and that option does not exist for the syslog driver: https://docs.docker.com/config/containers/logging/syslog/#options

That option is supported in the local and json-file driver.