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.

score 59 · Answer 1 · answered Feb 17 '18 at 15:51

59

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..

answered Feb 17 '18 at 15:51

madsonic

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this is brilliant – Obed Parlapiano May 02 '19 at 08:36
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Nice! And we can use `(! docker stats --no-stream &> /dev/null)` to silence the error messages while it's waiting. – Maximilian Feb 02 '21 at 03:29
The error wasn't silenced when I did this @Maximilian – jackdewinter Feb 10 '22 at 13:10

score 29 · Answer 2 · answered Feb 26 '20 at 18:01

29

This works for me on Ubuntu

$ systemctl status docker

answered Feb 26 '20 at 18:01

morpheus

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This works in Redhat 8 as well – Yeasin Ar Rahman Oct 24 '22 at 05:28

score 21 · Answer 3 · answered Nov 10 '21 at 23:04

21

if curl -s --unix-socket /var/run/docker.sock http/_ping 2>&1 >/dev/null
then
  echo "Running"
else
  echo "Not running"
fi

Ref: Docker api v1.28

answered Nov 10 '21 at 23:04

Gongora

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This should get way more upvotes – D3strukt0r Jan 31 '23 at 07:22
I wonder how to do the same with `wget` ? – Enissay Feb 17 '23 at 23:22
@Enissay `wget` isn't appropriate for this, and that's without saying it isn't a tool shipped by default in Operating Systems like MacOS, while `curl` is available immediately without extra steps. – Gongora Feb 20 '23 at 21:05

score 19 · Accepted Answer · edited Feb 17 '19 at 08:02

19

You have a utility called pgrep on almost all the Linux systems.

You can just do:

pgrep -f docker > /dev/null || echo "starting docker"

Replace the echo command with your docker starting command.

edited Feb 17 '19 at 08:02

Radagast the Brown

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answered May 15 '17 at 12:00

anubhava

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I am aware that the question does not ask for this but on mac pgrep always find a process, as `com.docker.vmne` persists when docker is not running – Scott Anderson Feb 03 '20 at 00:23
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To @ScottAnderson's point, if 'Docker Desktop' on MacOS is NOT running, `pgrep -f docker` will return a single value with a low (e.g. 3 digit) pid. When 'Docker Desktop' on MacOS is running, the same command will return a list of higher (5 digit) pid. So for the MacOS-specific use case, I think `pgrep -f Docker.app` is what you want. – bcdady May 06 '21 at 00:10

score 7 · Answer 5 · answered Aug 18 '21 at 16:35

You can simply:

docker version > /dev/null 2>&1

The exit code of that command will be stored to $? so you can check if it's 0, then docker is running.

docker version will exit 1 if daemon is not running. If other issues are encountered, such as docker not being installed at all, the exit code will vary.

But in the end of the day, if docker is installed and daemon is running, the exit code will be 0.

The 2>&1 will redirect stderr to stdout and > /dev/null will redirect stdout to /dev/null practically silencing the output no matter what was the result of the execution.

nice! Short and sweet. I like this for fail-fast sanity checking in scripts: if ! docker version > /dev/null 2>&1; then echo "Docker isn't running."; exit 1; fi — jgreve, Mar 26 '22 at 13:23

score 6 · Answer 6 · answered Jul 09 '18 at 17:59

The following works on macOS and on Windows if git bash is installed. On macOS open /Applications/Docker.app would start the docker deamon. Haven't seen anything similar for Windows however.

## check docker is running at all
## based on https://stackoverflow.com/questions/22009364/is-there-a-try-catch-command-in-bash
{
  ## will throw an error if the docker daemon is not running and jump
  ## to the next code chunk     
  docker ps -q
} || {
  echo "Docker is not running. Please start docker on your computer"
  echo "When docker has finished starting up press [ENTER} to continue"
  read
}

OMG, I found your comment on this gist too! I really like this solution! https://gist.github.com/peterver/ca2d60abc015d334e1054302265b27d9#gistcomment-2642238 — Andrew, Jun 22 '21 at 04:13

score 5 · Answer 7 · edited Jan 03 '20 at 22:44

5

You could also just check for the existence of /var/run/docker.pid.

edited Jan 03 '20 at 22:44

J. Scott Elblein

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answered May 15 '17 at 14:01

Raman Sailopal

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I think this should be `/var/run/docker.sock` for macOS. – Andrew Jun 22 '21 at 03:37
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This symlink seems to exist even when docker isn't running :/ – Andrew Jun 22 '21 at 04:10

giuliot · Answer 8 · 2022-03-18T11:07:05.627

Following @madsonic, I went for the following

#!/bin/bash
if (! docker stats --no-stream 2>/dev/null); then
  # On Mac OS this would be the terminal command to launch Docker
  open /Applications/Docker.app
  echo -n "Waiting for Docker to launch"
  sleep 1
  # Wait until Docker daemon is running and has completed initialisation
  while (! docker stats --no-stream >/dev/null 2>&1); do
    # Docker takes a few seconds to initialize
    echo -n "."
    sleep 1
  done
fi
echo
echo "Docker started"

score -1 · Answer 9 · answered May 15 '17 at 11:58

-1

A function could looks so:

isRunning {
    `ps -ef | grep "[d]ocker" | awk {'print $2'}`
}

I created a script to start, stop, restart a mongodb-server. You only need to change some path inside the scripts, and i also works for you: Script

answered May 15 '17 at 11:58

FrankTheTank_12345

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`ps -C docker -opid=` – Roman Kiselenko May 15 '17 at 12:21

score -2 · Answer 10 · edited Oct 15 '19 at 09:41

-2

I'm sure you want to start the docker daemon so here's the code to start it before executing your Docker run statement:

sudo systemctl start docker

edited Oct 15 '19 at 09:41

RobC

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answered Oct 15 '19 at 09:17

Ochieng'

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How to check if docker daemon is running?

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