Quick Docker setup on vagrant machine.

Docker

Docker is a Linux container, written in Go and based on lxc (self-described as “chroot on steroids”) and AUFS. Instead of providing a full VM, like you get with Vagrant, Docker provides you lightweight containers, that share the same kernel and allow to safely execute independent processes.
Docker is attractive for many reasons:

• Lightweight; images are much lighter than full VMs, and spinning off a new instance is lightning fast (in the range of seconds instead of minutes).
• Version control of the images, which makes it much more convenient to handle builds.
• Lots of images (again), just have a look at the docker public index of images.

Let’s set up a Docker container on your Vagrant machine:

1. SSH in Vagrant if you’re not in already:
   

    $ vagrant ssh

2. Install Docker, as explained on the official website:
   

    $ sudo apt-get update
    $ sudo apt-get install linux-image-generic-lts-raring linux-headers-generic-lts-raring
    $ sudo reboot
    $ sudo sh -c "curl https://get.docker.io/gpg | apt-key add -"
    $ sudo sh -c "echo deb http://get.docker.io/ubuntu docker main > /etc/apt/sources.list.d/docker.list"
    $ sudo apt-get update
    $ sudo apt-get install lxc-docker

3. Verify it worked by trying to build your first container:
   

    $ sudo docker run -i -t ubuntu /bin/bash

4. Great, but we’ll need more than a vanilla Linux. To add our dependencies, for example to run a Node.js + MongoDB app, we’re gonna start by creating a Dockerfile:
   

    FROM ubuntu
    MAINTAINER My Self me@example.com
    
    # Fetch Nodejs from the official repo (binary .. no hassle to build, etc.)
    ADD http://nodejs.org/dist/v0.10.19/node-v0.10.19-linux-x64.tar.gz /opt/
    
    # Untar and add to the PATH
    RUN cd /opt && tar xzf node-v0.10.19-linux-x64.tar.gz
    RUN ln -s /opt/node-v0.10.19-linux-x64 /opt/node
    RUN echo "export PATH=/opt/node/bin:$PATH" >> /etc/profile
    
    # A little cheat for upstart ;)
    RUN dpkg-divert --local --rename --add /sbin/initctl
    RUN ln -s /bin/true /sbin/initctl
    
    # Update apt sources list to fetch mongodb and a few key packages
    RUN echo "deb http://archive.ubuntu.com/ubuntu precise universe" >> /etc/apt/sources.list
    RUN apt-get update
    RUN apt-get install -y python git
    RUN apt-get install -y mongodb
    
    # Finally - we wanna be able to SSH in
    RUN apt-get install -y openssh-server
    RUN mkdir /var/run/sshd
    
    # And we want our SSH key to be added
    RUN mkdir /root/.ssh && chmod 700 /root/.ssh
    ADD id_rsa.pub /root/.ssh/authorized_keys
    RUN chmod 400 /root/.ssh/authorized_keys && chown root. /root/.ssh/authorized_keys
    
    # Expose a bunch of ports .. 22 for SSH and 3000 for our node app
    EXPOSE 22 3000
    
    ENTRYPOINT ["/usr/sbin/sshd", "-D"]

5. Let’s build our image now:
   

    $ sudo docker build .
    
    # Missing file id_rsa.pub ... hahaha ! You need an ssh key for your vagrant user
    $ ssh-keygen
    $ cp -a /home/vagrant/.ssh/id_rsa.pub .
    
    # Try again
    $ sudo docker build .
    
    # Great Success! High Five!

6. Now, let’s spin off a container with that setup and log into it ($MY_NEW_IMAGE_ID is the last id the build process returned to you):
   

    $ sudo docker run -p 40022:22 -p 80:3000 -d $MY_NEW_IMAGE_ID
    $ ssh root@localhost -p 40022

You now have a Docker container, inside a Vagrant box, ready to run a Node.js app.


Reference:

1. http://devo.ps