Docker in Docker(DND) is not starting

Question

I have a simple Ubuntu 16.10 container which has docker.io installed.

The docker process terminates after it starts and log has this information. Any troubleshooting suggestions?

$ docker run -it --name dcos-ubuntu-python5 python-docker /bin/bash

root@5ff6bb6b6dc7:/# docker run hello-world
docker: Cannot connect to the Docker daemon. Is the docker daemon running on this host?.
See 'docker run --help'.

root@5ff6bb6b6dc7:/# service docker start
 * Starting Docker: docker                                                                                                                                          [ OK ]
root@5ff6bb6b6dc7:/# service docker status
 * Docker is not running

root@5ff6bb6b6dc7:/# tail -f /var/log/docker.log
time="2017-12-21T17:09:45.464736873Z" level=info msg="libcontainerd: new containerd process, pid: 50"
time="2017-12-21T17:09:46.472578239Z" level=fatal msg="Error starting daemon: error initializing graphdriver: operation not permitted"

score 1 · Accepted Answer · answered Dec 21 '17 at 17:36

1

Why do you want to run docker within docker container?

Docker-in-Docker is developed to help docker development. And it needs --privileged flag to run docker container.(Please read jpetazzo's blog here.)

If you really want to execute docker in docker container, you also have other options.

Bind mount docker.sock. Some people call this DooD(Docker-outside-of-Docker)

docker run -v /var/run/docker.sock:/var/run/docker.sock ...
Install docker(client) and specify DOCKER_HOST to access remote docker daemon. Be careful about socket protection with certificates.

answered Dec 21 '17 at 17:36

SunghoMoon

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I think, it is discouraging that you answer a question starting "Why do you want to run docker within docker container?" – Senthil Kumaran Dec 21 '17 at 18:52
This is because the way to execute docker in docker container depends on the purpose. – SunghoMoon Dec 21 '17 at 18:57
That makes sense. Thank you! – Senthil Kumaran Dec 21 '17 at 20:13

score 0 · Answer 2 · answered Dec 21 '17 at 17:20

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Are you running docker as sudo if not run as sudo or

Else add user group to docker

docker group. For this run following command:

sudo usermod -aG docker $USER

answered Dec 21 '17 at 17:20

sanath meti

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score 0 · Answer 3 · answered Dec 21 '17 at 18:53

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The answer was simple.

docker run -it --privileged --name dcos-ubuntu-python5 python-docker /bin/bash

(This was also mentioned partly in @SunghoMoon's response. So Credits to him).

answered Dec 21 '17 at 18:53

Senthil Kumaran

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Docker in Docker(DND) is not starting

3 Answers3