service docker start fails (daemon is not a docker command)

Question

I have a problem after I have tried to restart docker. Since then, service docker start returns "start: Job failed to start".

This may have started once I have changed docker.conf. I have tried to reupload it using the command

wget -O /etc/init/docker.conf https://raw.githubusercontent.com/docker/docker/master/contrib/init/upstart/docker.conf

however, I was not lucky to fix this.

cat /var/log/upstart/docker.log returns:

Waiting for /var/run/docker.sock
docker: 'daemon' is not a docker command. See 'docker --help'.
Waiting for /var/run/docker.sock
docker: 'daemon' is not a docker command. See 'docker --help'.
Waiting for /var/run/docker.sock
docker: 'daemon' is not a docker command. See 'docker --help'.

Any help would be really appreciated.

Answer 1

You likely have an old version of docker installed; the docker daemon subcommand was added in docker 1.8. Before that, the daemon was started using the -d / --daemon option (docker -d).

The version of the upstart-configuration you downloaded is intended for the current docker release; for older versions of docker, be sure to download the version that matches the version you've installed, for example; https://raw.githubusercontent.com/docker/docker/v1.7.1/contrib/init/upstart/docker.conf

I would suggest to upgrade to a more recent version of docker, because versions older than 1.8 are now getting quite old (in Docker terms)