Ansible Role: Docker

Setup 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 2.7 or higher installation. This role makes use of the Ansible json_filter that requires jmespath to be installed on the Ansible machine. See the requirements.txt file for further details on the specific version of jmespath required by the role.

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. 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_package_state: present

Set it to latest to force the upgrade of the installed Docker package to the latest version.

docker_dependencies: "{{ default_docker_dependencies }}"

Additional support packages to be installed alongside Docker 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_override: ""
# docker_service_override: |
# [Service]
# ExecStart=
# ExecStart=/usr/bin/dockerd

Contect written to the systemd unit drop-in overriding the default Docker service definition.

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_cli_package_name: "docker-ce-cli"

Name of the package providing the Docker CLI.

docker_cli_package_version: ""

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

docker_cli_package_state: present

Set it to latest to force the upgrade of the installed Docker CLI package to the latest version.

containerd_package_name: "containerd.io"

Name of the package providing containerd.

containerd_package_version: ""

Version of the containerd package to be installed. When set to "" the latest available version will be installed.

containerd_package_state: present

Set it to latest to force the upgrade of the installed containerd package to the latest version.

containerd_service_override: |
  [Service]
  ExecStartPre=

Contect written to the systemd unit drop-in overriding the default containerd service definition.

containerd_service_state: "started"
containerd_service_enabled: "yes"

State of the containerd service.

docker_compose_version: ""

Version of docker-compose to be installed via python-pip. When set to "" the latest available version will be installed.

docker_py_package_name: "docker"

Name of the python-pip package providing docker-py

docker_py_package_version: ""

Version of the docker-py package to be installed.

docker_py_package_state: present

Installation state of the docker-py package. Set it to 'latest' to upgrade the Docker CLI to the latest version.

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.

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

Network interface to 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.

skip_repo: false
skip_containerd: false
skip_engine: false
skip_cli: false
skip_swarm: false
skip_group: false
skip_docker_py: false
skip_docker_compose: 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 py36-ansible29 -- molecule test -s swarm-singlenode

License

MIT

Author Information

Andrea Tosatto (@_hilbert_)