bash - How to check if docker daemon is running?

Question

I am trying to create a bash utility script to check if a docker daemon is running in my server. Is there a better way of checking if the docker daemon is running in my server other than running a code like this?

ps -ef | grep docker
root      1250     1  0 13:28 ?        00:00:04 /usr/bin/dockerd --selinux-enabled
root      1598  1250  0 13:28 ?        00:00:00 docker-containerd -l unix:///var/run/docker/libcontainerd/docker-containerd.sock --shim docker-containerd-shim --metrics-interval=0 --start-timeout 2m --state-dir /var/run/docker/libcontainerd/containerd --runtime docker-runc
root     10997 10916  0 19:47 pts/0    00:00:00 grep --color=auto docker

I would like to create a bash shell script that will check if my docker daemon is running. If it is running then do nothing but if it is not then have the docker daemon started.

My pseudocode is something like this. I am thinking of parsing the output of my ps -ef but I just would like to know if there is a more efficient way of doing my pseudocode.

if(docker is not running)

          run docker

end

P.S. I am no linux expert and I just need to do this utility on my own environment.

Answer 1

I made a little Script (Mac Osx) to ensure Docker is running by checking the exit code of docker stats.

#!/bin/bash
#Open Docker, only if is not running
if (! docker stats --no-stream ); then
  # On Mac OS this would be the terminal command to launch Docker
  open /Applications/Docker.app
 #Wait until Docker daemon is running and has completed initialisation
while (! docker stats --no-stream ); do
  # Docker takes a few seconds to initialize
  echo "Waiting for Docker to launch..."
  sleep 1
done
fi

#Start the Container..