How to check if the docker engine and a docker container are running?

Question

If you are looking for a specific container, you can run:

if [ "$( docker container inspect -f '{{.State.Running}}' $container_name )" == "true" ]; then ...

To avoid issues with a container that is in a crash loop and constantly restarting from showing that it's up, the above can be improved by checking the Status field:

if [ "$( docker container inspect -f '{{.State.Status}}' $container_name )" == "running" ]; then ...

If you want to know if dockerd is running itself on the local machine and you have systemd installed, you can run:

systemctl show --property ActiveState docker

You can also connect to docker with docker info or docker version and they will error out if the daemon is unavailable.

I ended up using

docker info

to check with a bash script if docker engine is running.

EDIT: which can be used to fail your script if docker isn't running, like so:

#!/usr/bin/env bash
if ! docker info > /dev/null 2>&1; then
  echo "This script uses docker, and it isn't running - please start docker and try again!"
  exit 1
fi

List all containers:

docker container ls -a

ls = list
-a = all

Check the column "status"

you can check docker state using: systemctl is-active docker

➜  ~  systemctl is-active docker
active

you can use it as:

➜  ~  if [ "$(systemctl is-active docker)" = "active" ]; then echo "is alive :)" ; fi
is alive :)

➜  ~  sudo systemctl stop docker

➜  ~  if [ "$(systemctl is-active docker)" = "active" ]; then echo "is alive :)" ; fi
 * empty response *

For OS X users (Mojave 10.14.3)

Here is what i use in my Bash script to test if Docker is running or not

# Check if docker is running
if ! docker info >/dev/null 2>&1; then
    echo "Docker does not seem to be running, run it first and retry"
    exit 1
fi