Docker Support

Roboconf has a target implementation for Docker.
From the Roboconf perspective, Docker is seen as a kind of IaaS. Roboconf may create and manage docker containers, that run Roboconf agents (just like VMs) and can be used as deployment targets.

To install it, open the DM’s interactive mode and type in…

# Here in version 0.2
bundle:install mvn:net.roboconf/roboconf-target-docker/0.2
bundle:start <bundle-id>

Sample target.properties.
Just copy / paste and edit.

# Configuration file for Docker
target.id = docker

docker.endpoint = http://localhost:4243
docker.image = 0f3087570887
docker.user = guest
docker.password = guest

Here is a complete description of the parameters for Docker.

Docker Configuration

Here, we assume Docker is already installed on your system (e.g. by using “apt-get install lxc-docker” on Ubuntu, or see docker.com for other platforms). Note that Docker runs mainly on Linux 64-bit systems, although some ports may be available for other platforms.

It is recommended to use docker version 1.3.x or later.

Configure the TCP port for Docker Containers

Roboconf needs Docker to be available on a TCP port.
To enable it, edit /etc/default/docker, and define DOCKER_OPTS there.

# Make Docker listen on TCP port 4243 (along with local Unix socket)
DOCKER_OPTS="-H=tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock"

Then, simply restart docker.

sudo stop docker
sudo start docker

Prepare a Docker Image

Obtain a Docker Linux image (e.g. Ubuntu), then start a Docker container using it.

docker pull ubuntu
docker run -v /tmp:/roboconf -t -i ubuntu /bin/bash

Note: the container started above shares the local /tmp as /roboconf under Docker (using the -v option).
This can be useful to share files between the local file system and the Docker container (e.g. to install the Roboconf agent).

Let’s assume you have copied the Roboconf agent in the shared /roboconf directory (here, the local /tmp).
In the Docker container, execute the following commands.

apt-get update
apt-get install openjdk-7-jre-headless
cd /usr/local
tar xvzf /roboconf/roboconf-karaf-dist-agent.tar.gz
ln -s roboconf-karaf-dist-agent/ roboconf-agent

Now, you have to add a start.sh executable script in the /usr/local/roboconf-agent directory.
Set the following content (the script is mainly used to complete the agent setup at startup time).

#!/bin/bash
# Startup script for docker agent
cd /usr/local/roboconf-agent
echo "# Roboconf agent configuration - DO NOT EDIT: Generated by roboconf" >  etc/net.roboconf.agent.configuration.cfg

for p in "$@"
do
	echo $p >> etc/net.roboconf.agent.configuration.cfg
done

cd bin
./karaf

The container is now ready to become a Docker image.
Outside docker, keep track of its ID, that will be useful to build the image.

• Use docker ps to obtain your container ID.
• Then, docker commit -m “Roboconf-Agent-Image” <your container ID> roboconf-agent:some-tag

Now, your image is created.
Retrieve its image ID using docker images, and use it as docker.image in the Roboconf configuration (target.properties).

Some Docker Tips

Here is a reminder of some Docker commands.

To list docker images:
docker images

To remove a docker image:
docker rmi <image-ID>

To run interactively a docker image (thus launching a container):
docker run -i -v /tmp:/roboconf -t <image-ID> /bin/bash

Note: the -v option is used there to share the local “/tmp” as “/roboconf” in the container, which is useful to exchange files.

To list running docker containers:
docker ps (or, to list them all, “docker ps -a”)

to attach a shell script to a running container:
docker exec -ti <container-ID> /bin/bash

To remove a docker container:
docker rm <container-ID>

To remove all exited containers:
docker ps -a | grep Exit | cut -d ‘ ‘ -f 1 | xargs docker rm