Docker

New in version 0.1.

Docker is a container manager and scheduler. In their words, it “allows you to package an application with all of its dependencies into a standardized unit for software development.” Their site has more on what Docker is. We use it in Mantl to ship units of work around the cluster, combined with Marathon‘s scheduling.

Variables

docker_source

Specify origin of docker packages.

Possible values: docker, redhat.

Default: docker` -- using packages from ``Docker, inc.

docker_tcp

Open the Docker socket to TCP control?

Note that if TCP/TLS are enabled after your cluster is already built, you’ll run into https://github.com/docker/docker/issues/17902 and have to restart all your containers manually:

::

$ ansible –become all -a ‘systemctl start nginx-consul’ $ ansible –become role=control -a ‘systemctl start nginx-mantlui’ $ ansible –become role=control -a ‘systemctl start kubelet’ $ ansible –become role=kubeworker -a ‘systemctl start kubelet’

Default: false

docker_tcp_tls

Protect the Docker socket with TLS authentication. TLS should always be used in conjunction with docker_tcp.

Defaults to the value of docker_tcp.

Using a private Docker registry

In addition to the open, official Docker registry at https://hub.docker.com, one can use a private in-house docker registry for storing and pulling images. Docker Hub also supports storing private images.

One must configure credentials in order to use private repositories. This is done with the security-setup script, run it with the flag --use-private-docker-registry=true. It will then ask you for username, password and e-mail address for the registry user. You can also specify a custom URL for an in-house Docker registry, or omit it, in which case it will default to the official registry, https://index.docker.io/v1/.

In addition to configuring access to the specified private docker registries, this will also create an archive that can be used to supply credentials to Marathon tasks that require access to those registries. You can specify the path to the generated credentials archive in the uris key of your Marathon app definition:

...
"uris": [
  "file:///etc/docker.tar.gz"
],
...

See the Marathon documentation for more information.