In this post we will show how to configure a compute node in OpenStack to launch Docker containers. We assume that you already have a working OpenStack installation. The configuration we describe below worked for OpenStack Juno, while the controller and compute nodes were running Ubuntu 14.04 LTS.

Install Docker and Docker driver for OpenStack on the compute node

Installing Docker in Ubuntu (Docker only works for 64 bit Ubuntu OS):

 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

Add nova to the docker group and restart the compute service to pick up the change:

sudo usermod -G docker nova
sudo service nova-compute restart

Install the nova-docker driver:

sudo apt-get install python-pip
sudo apt-get install python-dev
git clone https://github.com/stackforge/nova-docker
cd nova-docker
git checkout stable/juno
sudo python setup.py install

Configuring the compute and the controller nodes for Docker

Nova configuration in the compute node

With admin privileges edit the configuration file /etc/nova/nova.conf according to the following options:

[DEFAULT]
compute_driver = novadocker.virt.docker.DockerDriver
vif_plugging_is_fatal=False 
vif_pligging_timeout=0

Create the directory /etc/nova/rootwrap.d, if it does not already exist, and inside that directory create a file “docker.filters” with the following content:

# nova-rootwrap command filters for setting up network in the docker driver
# This file should be owned by (and only-writeable by) the root 
[Filters]
# nova/virt/docker/driver.py: 'ln', '-sf', '/var/run/netns/.*'
ln: CommandFilter, /bin/ln, root

Glance configuration in the controller node

Glance also needs to be configured to support the Docker container format, in /etc/glance/glance-api.conf (found in controller):

[DEFAULT]
container_formats = ami,ari,aki,bare,ovf,docker

And then restart the Glance service:

service glance-api restart
service glance-registry restart

Now, back to the compute node

Do the following:

sudo chmod 666/var/run/docker.sock
sudo chmod 777/var/run/libvirt/libvirt-sock
service nova-compute restart
sudo service docker restart

[DEFAULT]
compute_driver=novadocker.virt.docker.DockerDriver
#[libvirt]
#virt_type=kvm

Launching Docker containers

Example: A minimal container that runs an http server (thttpd) on port 80

In the compute node:

In the controller node, first source your OpenStack RC file and then boot your docker instance:

Now, check instances in Openstack Horizon to see our newly created instance is running. Then, assign a floating IP address through Openstack horizon and try http://<assigned_ip>/ to see if it is working.

That’s all!