It may work on other distros and additional operating systems will be
supported in the future. It's definitely been used with the following
too:
Archlinux
Amazon Linux
Fedora
Gentoo
Examples
Launch vNext app in Docker using Puppet
This example contains a fairly simple example using Vagrant to launch a
Linux virtual machine, then Puppet to install Docker, build an image and
run a container. For added spice the container runs a ASP.NET vNext
application.
Multihost containers connected with
Consul
Launch multiple hosts running simple application containers and
connect them together using Nginx updated by Consul and Puppet.
By default this sets up the docker hosted repository if necessary for your OS
and installs the docker package and on Ubuntu, any required Kernel extensions.
If you don't want this module to mess about with your Kernel then you can disable
this feature like so. It is only enabled (and supported) by default on Ubuntu:
class { 'docker':
manage_kernel => false,
}
If you want to configure your package sources independently, inform this module
to not auto-include upstream sources (This is already disabled on Archlinux
as there is no further upstream):
class { 'docker':
use_upstream_package_source => false,
}
Docker recently launched new official
repositories
which are now the default for the module from version 5. If you want to
stick with the old repositories you can do so with the following:
Docker also provide a commercially
supported
version of the Docker Engine, called Docker CS, available from a separate repository.
This can be installed with the module using the following:
class { 'docker':
docker_cs => true,
}
The module also now uses the upstream repositories by default for RHEL
based distros, including Fedora. If you want to stick with the distro packages
you should use the following:
class { 'docker':
use_upstream_package_source => false,
package_name => 'docker',
}
By default the docker daemon will bind to a unix socket at
/var/run/docker.sock. This can be changed, as well as binding to a tcp
socket if required.
Unless specified this installs the latest version of docker from the docker
repository on first run. However if you want to specify a specific version you
can do so, unless you are using Archlinux which only supports the latest release.
Note that this relies on a package with that version existing in the reposiroty.
class { 'docker':
version => '0.5.5',
}
And if you want to install a specific rpm package of docker you can do so:
And if you want to track the latest version you can do so:
class { 'docker':
version => 'latest',
}
In some cases dns resolution won't work well in the container unless you give a dns server to the docker daemon like this:
class { 'docker':
dns => '8.8.8.8',
}
To add users to the Docker group you can pass an array like this:
class { 'docker':
docker_users => ['user1', 'user2'],
}
To add daemon labels you can pass an array like this:
class { 'docker':
labels => ['storage=ssd','stage=production'],
}
The class contains lots of other options, please see the inline code
documentation for the full options.
Images
The next step is probably to install a docker image; for this we have a defined type which can be used like so:
docker::image { 'base': }
This is equivalent to running docker pull base. This is downloading a large binary so on first run can take a while. For that reason this define turns off the default 5 minute timeout for exec. Takes an optional parameter for installing image tags that is the equivalent to running docker pull -t="precise" ubuntu:
Note: images will only install if an image of that name does not already exist.
A images can also be added/build from a dockerfile with the docker_file property, this equivalent to running docker build -t ubuntu - < /tmp/Dockerfile
Images can also be added/build from a directory containing a dockerfile with the docker_dir property, this is equivalent to running docker build -t ubuntu /tmp/ubuntu_image
docker run -d base /bin/sh -c "while true; do echo hello world; sleep 1; done"
This will launch a Docker container managed by the local init system.
Run also takes a number of optional parameters:
docker::run { 'helloworld':
image => 'base',
command => '/bin/sh -c "while true; do echo hello world; sleep 1; done"',
ports => ['4444', '4555'],
expose => ['4666', '4777'],
links => ['mysql:db'],
net => 'my-user-def-net',
volumes => ['/var/lib/couchdb', '/var/log'],
volumes_from => '6446ea52fbc9',
memory_limit => '10m', # (format: '<number><unit>', where unit = b, k, m or g)
cpuset => ['0', '3'],
username => 'example',
hostname => 'example.com',
env => ['FOO=BAR', 'FOO2=BAR2'],
env_file => ['/etc/foo', '/etc/bar'],
dns => ['8.8.8.8', '8.8.4.4'],
restart_service => true,
privileged => false,
pull_on_start => false,
before_stop => 'echo "So Long, and Thanks for All the Fish"',
before_start => 'echo "Run this on the host before starting the Docker container"',
after => [ 'container_b', 'mysql' ],
depends => [ 'container_a', 'postgres' ],
extra_parameters => [ '--restart=always' ],
}
Ports, expose, env, env_file, dns and volumes can be set with either a single string or as above with an array of values.
Specifying pull_on_start will pull the image before each time it is started.
Specifying before_stop will execute a command before stopping the container.
The after option allows expressing containers that must be started before. This affects the generation of the init.d/systemd script.
The depends option allows expressing container dependencies. The depended container will be started before this container(s), and this container will be stopped before the depended container(s). This affects the generation of the init.d/systemd script. You can use depend_services to specify dependency for generic services (non-docker) that should be started before this container.
extra_parameters : An array of additional command line arguments to pass to the docker run command. Useful for adding additional new or experimental options that the module does not yet support.
The service file created for systemd based systems enables automatic restarting of the service on failure by default.
To use an image tag just append the tag name to the image name separated by a semicolon:
By default the generated init scripts will remove the container (but not
any associated volumes) when the service is stopped or started. This
behaviour can be modified using the following, with defaults shown:
Only the name is required, along with an ensure value. If you don't pass
a driver Docker network will use the default bridge. Note that some
networks require the Docker daemon to be configured to use them, for
instance for the overlay network you'll need a cluster store configured.
You can do that on the docker class like so:
The network defined can then be used on a docker::run resource with the net parameter.
Compose
Docker Compose allows for describing a set of containers in a simple
YAML format, and then running a command to build and run those
containers. The docker_compose type included in the module allows for
using Puppet to run Compose. This means you can have Puppet remediate
any issues and make sure reality matches the model in your Compose
file.
Before using the docker_compose type make sure the docker-compose utility is installed:
class {'docker::compose':
ensure => present,
}
Here's an example. Given the following Compose file:
Now when Puppet runs it will automatically run Compose is required,
for example because the relevant Compose services aren't running.
You can also pass additional options (for example to enable experimental
features) as well as provide scaling rules. The following example
requests 2 containers be running for example. Puppet will now run
Compose if the number of containers for a given service don't match the
provided scale values.
It is also possible to give options to the docker-compose up command
such as --remove-orphans using the up_args option.
Swarm mode
Docker Engine 1.12 includes swarm mode for natively managing a cluster of Docker Engines called a swarm. You can now cluster your Docker engines with the one of the following Puppet resources.
For a swarm manager:
In the above example we have configured a swarm manager with init => true then set the advertise_addr and listen_addr. Both the advertise_addr and listen_addr are set for the cluster communications between nodes. Please note the advertise_addr and listen_addr must be set for a multihomed server. For more advance flags to configure raft snapshots etc please read the readme at the top of the docker::swarm class.
In this example we have joined a node to the cluster using join => true. For a worker node or second manager you need to pass a current managers ip address manager_ip => '192.168.1.1'
The other important configuration is the token you pass to the manager. The token will define the nodes role in the cluster, as there will be a token to create another manager and a different token for the worker nodes.
To remove a node from a cluster use the following:
Docker services allow to create distributed applications across multiple swarm nodes. A service is a set of containers that are replicated across your swarm.
To configure a service with Puppet code please see the following examples
In this example we are creating a service called redis, as it is a new service we have set create => true. The service_name resource is the name which Docker knows the service as. The image resource is the image you want to base the service off, publish is the ports that want exposed to the outside world for the service to be consumed, replicas sets the amount of tasks (containers) that you want running in the service, extra_params allows you to configure any of the other flags that Docker gives you when you create a service for more info see docker service create --help
To update the service
docker::services {'redis_update':
create => false,
update => true,
service_name => 'redis',
replicas => '3',
}
In this example we have taken the service that we created earlier `redis` set the `create => false` and this time added `update => true`. We then decleared the service name `redis` we have then updated the servce to have only 3 replicas, not 5. The `extra_params` resource is also available in the update class.
To scale a service
```puppet
docker::services {'redis_scale':
create => false,
scale => true,
service_name => 'redis',
replicas => '10',
}
In this example we have used the command docker service scale with Puppet code. We have taken our service redis set the create => false and scale => true When using scale you have to declare your service_name then the number of replicas that you want. In this example we are going to scale to 10
To remove a a service from your swarm just set ensure => absent and the service_name of your service.
Private registries
By default images will be pushed and pulled from index.docker.io unless you've specified a server. If you have your own private registry without authentication, you can fully qualify your image name. If your private registry requires authentication you may configure a registry:
