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I want to run docker inside another docker container. My main container is running in a virtualbox of OS Ubuntu 18.04 which is there on my Windows 10. On trying to run it, it is showing me as:

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

How can I resolve this issue?

atline
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Anurag Baheti
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  • Have you enabled `privileged` mode on the outer docker container? – dyz May 06 '19 at 04:27
  • Where is the docker client running? In Windows? Within your Ubuntu VM? Also, what command do you run to cause the error to occur? It may help to simply copy/paste the command you ran and the output from your terminal. – ctt May 06 '19 at 04:27
  • Docker client is running inside my Ubuntu VM. I am just running a simple 'docker run hello-world' command to check if it is running properly. I have not enabled privileged mode. – Anurag Baheti May 06 '19 at 04:47
  • I am running electric-flow in a docker container in my Ubuntu virtual-box using this docker command: **docker run --name efserver --hostname=efserver -d -p 8080:8080 -p 9990:9990 -p 7800:7800 -p 7070:80 -p 443:443 -p 8443:8443 -p 8200:8200 -i -t ecdocker/eflow-ce**. Inside this docker container, I want to install and run docker so that my CI/CD pipeline in electric-flow can access and use docker commands. – Anurag Baheti May 06 '19 at 04:51

2 Answers2

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Yes, you can do this. Check for dind (docker in docker) on docker webpage how to achieve it: https://hub.docker.com/_/docker

Your error indicates that either dockerd in the top level container is not running or you didn't mount docker.sock on the dependent container to communicate with dockerd running on your top-level container.

Miq
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I am running electric-flow in a docker container in my Ubuntu virtual-box using this docker command: docker run --name efserver --hostname=efserver -d -p 8080:8080 -p 9990:9990 -p 7800:7800 -p 7070:80 -p 443:443 -p 8443:8443 -p 8200:8200 -i -t ecdocker/eflow-ce. Inside this docker container, I want to install and run docker so that my CI/CD pipeline in electric-flow can access and use docker commands.

From your above description, ecdocker/eflow-ce is your CI/CD solution container, and you just want to use docker command in this container, then you did not need dind solution. You can just access to a container's host docker server.

Something like follows:

docker run --privileged --name efserver --hostname=efserver -d -p 8080:8080 -p 9990:9990 -p 7800:7800 -p 7070:80 -p 443:443 -p 8443:8443 -p 8200:8200 -v $(which docker):/usr/bin/docker -v /var/run/docker.sock:/var/run/docker.sock -i -t ecdocker/eflow-ce

Compared to your old command:

  • Add --privileged
  • Add -v $(which docker):/usr/bin/docker, then you can use docker client in container.
  • Add -v /var/run/docker.sock:/var/run/docker.sock, then you can access host's docker daemon using client in container.
atline
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