check-if-docker-container-is-running.md

Check if a docker container is running based on the container name

If you want to find out if a Docker container with a specific name is currently running you can use the docker ps command and then some grep, awk, sed chain. Alternatively, you can query the Docker Remote API and get a JSON response which you can parse with jq.

Using the docker remote API

#!/bin/sh
# filename: is_container_running.sh
# requirements: docker running locally, jq installed
# usage: ./is_container_running.sh NameOfContainer

curl -s --unix-socket /var/run/docker.sock "http:/containers/json?all=false" |\
  jq --arg containername "/$1" '[ .[].Names | .[] | . == $containername ] | reduce .[] as $item (false; . | $item)'

Using grep and cut and return 0/1

#!/bin/sh
docker ps | grep $1 | rev | cut -d ' ' -f 1 | rev | grep -c $1

##Using only grep

#!/bin/sh
docker ps | grep $1 | grep -o '[^\ ]*$' | grep -c $1

##Using grep and return an exit code e.g. if you want to process the result in another check

#!/bin/sh
docker ps | grep $1 | grep -o '[^\ ]*$' | grep -q $1