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

Question

In a script  I need to check  a  Is the docker engine running  b  Given a container name  is that docker container running   the initial wording of this question was ambiguous  with some people interpreting it as  quot check docker engine quot   and others as  quot check docker container quot

User · Answer

If the underlying goal is  How can I start a container when Docker starts    We can use Docker s restart policy  To add a restart policy to an existing container   Docker  Add a restart policy to a container that was already created  Example   docker update --restart always  lt container gt

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Sometimes you don t know the full container name  in this case this is what worked for me  if docker ps   grep -q keyword then      echo  quot Running  quot  else     echo  quot Not running  quot      exit 1 fi  We list all the running container processes  docker ps -a would show us also not running ones  but that s not what I needed   we search for a specific word  grep part  and simply fail if we did not find at least one running container whose name contains our keyword

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For the answer to your first question refer to this answer - https   stackoverflow com a 65447848 4691279 For your second question - you can use command like docker ps --filter  quot name  lt  lt  lt YOUR CONTAINER NAME gt  gt  gt  quot  to check whether a particular container is running or not   If Docker and Container both are running then you will get output like below    docker ps --filter  quot name nostalgic stallman quot   CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES        9b6247364a03        busybox              quot top quot                2 minutes ago       Up 2 minutes                            nostalgic stallman   If Docker is not running then you will get an error message saying docker daemon is not running   If Docker running but Container is not running then you will not get the container name in the output of this command

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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  gt  dev null 2 gt  amp 1  then     echo  quot Docker does not seem to be running  run it first and retry quot      exit 1 fi

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on a Mac you might see the image     if you right click on the docker icon then you see     alternatively   docker ps  and   docker run hello-world

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Run this command in the terminal  docker ps  If docker is not running  you wil get this message   Error response from daemon  dial unix docker raw sock  connect  connection refused

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You can check with this command systemctl status docker it will show the status of the docker  If you want to start you can use systemctl start docker instead of systemctl you can try also with service  service docker status and service docker start respectively

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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

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container status  true false   docker inspect --format    json  State Running    container-name true

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Any docker command  except docker -v   like docker ps If Docker is running  you ll get some valid response  otherwise you ll get a message that includes  Is your docker daemon up and running    You can also check your task manager

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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

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I have a more fleshed out example of using some of the work above in the context of a Gitea container  but it could easily be converted to another container based on the name  Also  you could probably use the docker ps --filter capability to set  GITEA CONTAINER in a newer system or one without docker-compose in use    Set to name or ID of the container to be watched  GITEA CONTAINER     bin docker-compose ps  grep git cut -f1 -d        Set timeout to the number of seconds you are willing to wait  timeout 500  counter 0   This first echo is important for keeping the output clean and not overwriting the previous line of output  echo  quot Waiting for  GITEA CONTAINER to be ready    counter    timeout   quot   This says that until docker inspect reports the container is in a running state  keep looping  until      docker inspect --format    json  State Running     GITEA CONTAINER     true     do      If we ve reached the timeout period  report that and exit to prevent running an infinite loop    if     timeout -lt  counter     then     echo  quot ERROR  Timed out waiting for  GITEA CONTAINER to come up  quot      exit 1   fi      Every 5 seconds update the status   if     counter   5    0     then     echo -e  quot  e 1A e KWaiting for  GITEA CONTAINER to be ready    counter    timeout   quot    fi      Wait a second and increment the counter   sleep 1s     counter      done

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I ended up using  docker info   to check with a bash script if docker engine is running

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Run   docker version   If docker is running you will see   Client  Docker Engine - Community  Version                  omitted   Server  Docker Engine - Community  Engine    Version                 omitted    If docker is not running you will see   Client  Docker Engine - Community  Version                  omitted   Error response from daemon  Bad response from Docker engine

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docker ps -a You can see all docker containers whether it is alive or dead

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How I check in SSH Run  systemctl  If response  Failed to get D-Bus connection  Operation not permitted Its a docker or WSL container

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List all containers    docker container ls -a    ls   list -a   all  Check the column  status

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You can also check if a particular docker container is running or not using following command   docker inspect postgres   grep  Running    This command will check if for example my postgres container is running or not and will return output as  Running   true  Hope this helps

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

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