Ansible Role: Docker

Setup a Docker on RHEL/CentOS and Debian/Ubuntu servers. The role supports Docker Engine's "Swarm Mode" (https://docs.docker.com/engine/swarm/) to create a cluster of Docker nodes.

Requirements

An Ansible 2.3 or higher installation.

Dependencies

None.

Role Variables

Available variables are listed below, along with default values (see [defaults/main.yml](defaults/main.yml)):

docker_repo: "{{ docker_repo_ce_stable }}"

The repository proving the Docker packages. The Docker Community stable repository is configured by default. Additional repositories are defined in [vars/main.yml](vars/main.yml) including the edge, test and nightly repositories. To skip the configuration of the repository and use the system repositories set skip_repo: true.

docker_package_name: "docker-ce"

Name of the package providing the Docker daemon.

  docker_package_version: ""

Version of the Docker package to be installed on the target hosts. When set to "" the latest available version will be installed.

docker_dependencies: "{{ default_docker_dependencies }}"

Additional packages to be installed by the role. See [vars/RedHat.yml](vars/RedHat.yml) and [vars/Debian.yml](vars/Debian.yml) for the definition of the default_docker_dependencies variable.

docker_service_state: "started"
docker_service_enabled: "yes"

State of the Docker service.

docker_daemon_config: {}

Dictionary of Docker deamon configuration options to be written to /etc/docker/daemon.json. See Daemon configuration file for the detailed documentation of the available options.

docker_swarm_interface: "{{ ansible_default_ipv4['alias'] }}"

Setting docker_swarm_interface allows you to define which network interface will be used for cluster inter-communication.

docker_swarm_addr: "{{ hostvars[inventory_hostname]['ansible_' + docker_swarm_interface]['ipv4']['address'] }}"

Listen address for the Swarm raft API. By default, the ip address of docker_swarm_interface.

docker_swarm_port: 2377

Listen port for the Swarm raft API.

docker_group_name: "docker"
docker_group_users:
  - "{{ ansible_user }}"

Name of the Docker group and list of users to be added to docker_group_name to manage the Docker daemon. NB: The users must already exist in the system.

skip_repo: false
skip_engine: false
skip_group: false
skip_swarm: false
skip_docker_py: false

Switches allowing to disable specific functionalities of the role. If you want to use this role to install docker-engine without enabling swarm-mode set skip_swarm: true.

Swarm node labels

Node labels provide a flexible method of node organization. You can also use node labels in service constraints. Apply constraints when you create a service to limit the nodes where the scheduler assigns tasks for the service. You can define labels by swarm_labels variable, e.g:

$ cat inventory
...
[docker_swarm_manager]
swarm-01 swarm_labels=deploy

[docker_swarm_worker]
swarm-02 swarm_labels='["libvirt", "docker", "foo", "bar"]'
swarm-03
...

In this case:

$ docker inspect --format '{{json .Spec.Labels}}'  swarm-02 | jq
{
   "bar": "true",
   "docker": "true",
   "foo": "true",
   "libvirt": "true",
}

You can assign labels to cluster running playbook with --tags=swarm_labels

NB: Please note, all labels that are not defined in inventory will be removed

Example Playbook

$ cat inventory
swarm-01 ansible_ssh_host=172.10.10.1
swarm-02 ansible_ssh_host=172.10.10.2
swarm-03 ansible_ssh_host=172.10.10.3

[docker_engine]
swarm-01
swarm-02
swarm-03

[docker_swarm_manager]
swarm-01 swarm_labels=deploy

[docker_swarm_worker]
swarm-02 swarm_labels='["libvirt", "docker", "foo", "bar"]'
swarm-03

$ cat playbook.yml
- name: "Provision Docker Swarm Cluster"
  hosts: all
  roles:
    - { role: atosatto.docker-swarm }

Testing

Tests are performed by Molecule.

$ pip install tox

To test all the scenarios run

$ tox

To run a custom molecule command

$ tox -e py27-ansible23 -- molecule test -s swarm-cluster

The MOLECULE_DRIVER_NAME and MOLECULE_TARGET_DISTRO allows to change the Molecule driver from Docker to Vagrant and the tests target OS

$ MOLECULE_DRIVER_NAME=vagrant MOLECULE_TARGET_DISTRO=ubuntu-1604 tox

To test the role on Ubuntu instead of CentOS set the

License

MIT

Author Information

Andrea Tosatto (@_hilbert_)

pngmbh/ansible-dockerswarm