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I am using a docker container to build and deploy my software to a collection of ec2's. In the deployment script I build my software and then package it in a docker image. The image is pushed to my private registry, pulled by my production ec2's and then run. So essentially I will need to run docker within a docker container.
The problem is that I can't actually start docker on my container. If I try
service docker start I get
bash: service: command not found And if I try
docker -d I get
2014/10/07 15:54:35 docker daemon: 0.11.1-dev 02d20af/0.11.1; execdriver: native; graphdriver: [e2feb6f9] +job serveapi(unix:///var/run/docker.sock) [e2feb6f9] +job initserver() [e2feb6f9.initserver()] Creating server 2014/10/07 15:54:35 Listening for HTTP on unix (/var/run/docker.sock) [error] attach_loopback.go:42 There are no more loopback device available. loopback mounting failed [e2feb6f9] -job initserver() = ERR (1) 2014/10/07 15:54:35 loopback mounting failed The service command doesn't exist on the docker container so I can't start docker. I'm not sure what I should be doing now to start docker so I'm a bit stuck here, any help is appreciated.
A bit more information
Host machine is running fedora 20 (will eventually be running amazon linux on an ec2)
Docker container is running centos 7.0
Host is running Docker version 1.2.0, build fa7b24f/1.2.0
Container is running docker-0.11.1-22.el7.centos.x86_64
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You can't run Docker commands from a Dockerfile (and shouldn't as a general rule try to run Docker commands from within Docker containers) but you can write an ordinary shell script on the host that runs the docker build && docker run .
Introduction. Docker in Docker (also known as dind) is, as the name implies, running Docker on top of a Docker container. Controlling containers from a Docker container is not a particular use case but is often necessary to run CI tools such as Jenkins on top of a Docker container.
How about not running 'docker inside docker' and run docker on your host, but from within your docker container? Just mount your docker.sock and docker binary:
docker run -v /var/run/docker.sock:/run/docker.sock -v $(which docker):/bin/docker [your image]
https://github.com/sameersbn/docker-gitlab uses this approach to spin up docker containers, take a look at this image.
You can also take a look at: https://registry.hub.docker.com/u/mattgruter/doubledocker/
UPDATE on july 2016
The most current approach is to use docker:dind image, as described here: https://hub.docker.com/_/docker/
Short summary:
$ docker run --privileged --name some-docker -d docker:dind
and then: $ docker run --rm --link some-docker:docker docker info
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