I really like Docker – a very easy way to create runnable containers. I want to show you how you can create a Docker image that build all you Docker images (Inception!).
Use Cases for such a Docker image:
- Continuous Deployment
- Environments without build tools (but obviously with docker)
- because I can
So this docker-inception image should do the following:
- fetch your application and dockerfiles from a repo
- setup needed dev tools (nodejs, npm, mvn, ant, gradle…)
- compile the source
- build all docker images
- orchestrate the docker images, for example with fig
-> all but the last tasks are (static) RUN commands, while the orchestrate task is a CMD task that will run if you execute the image.
Here is an example Dockerfile I use:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | FROM dockerfile/nodejs:latest MAINTAINER Michael Vogt <michu@neophob.com> WORKDIR /builder # BUILD ENV VARS ENV GIT_BRANCHNAME feature-docker-leightweight # add bitbucket deployment key ADD assets/ /builder/ RUN chmod 600 /builder/key # install gem and compass (0.12.6 is available anymore) RUN apt-get update -qq && apt-get install -yqq --no-install-recommends ruby RUN gem install compass # add ssh wrapper to use private key RUN echo '#!/bin/bash\nssh -i /builder/key -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o GlobalKnownHostsFile=/dev/null $@' > ./my_git_ssh_wrapper && chmod +x ./my_git_ssh_wrapper # get source from git repo RUN GIT_SSH=/builder/my_git_ssh_wrapper git clone git@bitbucket.org:XXX/YYY.git -b $GIT_BRANCHNAME # install needed build modules RUN npm install -g grunt-cli@0.1.13 bower@1.3.9 # build RUN cd XXX/YYY && npm install && bower --allow-root install && grunt build && cd - # install fig RUN curl -L https://github.com/docker/fig/releases/download/0.5.2/linux > /usr/local/bin/fig && chmod +x /usr/local/bin/fig CMD fig up -d |
Some comments about this Dockerfile:
- Asset files: key (SSH Private key) and fig.yml
- I use bitbucket as git repo, thus the ssh key and the ssh wrapper
Build the docker image:
1 | docker build -t build-inception . |
Run the docker image:
1 | docker run --rm -v /var/run/docker.sock:/var/run/docker.sock -v $(which docker):$(which docker) build-inception |
Credits to http://blog.xebia.com/2014/07/04/create-the-smallest-possible-docker-container/.
