Puppet Docker pull an image and launch a container

Question

I am experimenting on integrating a containerization tool (docker) and config management tool (puppet). How can i pull an image from the repository and launch a container using puppet code?

Answer 1

• I hope you have docker module from puppet forge. If not do it.

$ sudo puppet module install garethr-docker
Notice: Preparing to install into /etc/puppet/modules ...
Notice: Downloading from https://forgeapi.puppetlabs.com ...
Notice: Installing -- do not interrupt ...
/etc/puppet/modules
|--- garethr-docker (v4.1.1)
  |-- puppetlabs-apt (v2.1.1)
  |-- puppetlabs-stdlib (v4.9.0)
  |-- stahnma-epel (v1.1.1)

• Here's a docker_example.pp

• The /etc/puppet/manifests/docker_example.pp should look something like:

include 'docker'
docker::image { 'ubuntu':
   image_tag => 'trusty',
}

• The module includes a single class:

include 'docker'

• By default, this sets up the docker hosted repository if necessary for our OS, and installs the docker package and on Ubuntu, any required Kernel extensions.

docker::image { 'ubuntu':
  image_tag => 'trusty'
}

• The image tags is equivalent to running docker pull -t="trusty" ubuntu. 

• Note that the image will only install if an image of that name does not already exist.

• Let's apply the puppet manifest (/etc/puppet/manifests/docker_example.pp) in order to get docker installed on our puppet master:

$ sudo puppet apply site.pp
...
Notice: Finished catalog run in 46.40 seconds

• check if docker has been properly installed:

$ sudo docker version
Client version: 1.7.1
Client API version: 1.19
Go version (client): go1.4.2
Git commit (client): 786b29d
OS/Arch (client): linux/amd64
Server version: 1.7.1
Server API version: 1.19
Go version (server): go1.4.2
Git commit (server): 786b29d
OS/Arch (server): linux/amd64

• Also, check that there is no running docker container:

$ sudo docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

• Check the installation of the ubuntu docker image:

$ sudo docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
ubuntu              trusty              91e54dfb1179        3 weeks ago         188.4 MB

• Now we have an image to work with. We can launch containers like this:

docker::run { 'helloworld':
  image   => 'ubuntu',
  command => '/bin/sh -c "while true; do echo hello world; sleep 1; done"',
}

 The above code snippet is equivalent to running the following:

docker run -d base /bin/sh -c "while true; do echo hello world; sleep 1; done"

This will launch a Docker container.