Docker

Ansible role to install and configure Docker container engine on RHEL/CentOS 7.

Main features:

• Supports overlay2 and devicemapper (with direct LVM) Docker storage drivers.
• Uses container-storage-setup (also known as docker-storage-setup) to set up Docker's storage.
• Prevents users from running devicemapper driver on a loopback device by default.
• Sets up convenient passwordless sudo access for running Docker for selected users as recommended by Dan Walsh, lead of Red Hat's Docker team.
• Supports authenticating with private Docker registries.

Limitations:

• Automatically applying changes to the Docker storage configuration for an existing system is not supported. You will have to manually remove the contents of the /var/lib/docker directory and then run the role again.

Requirements

This role requires Ansible 2.4 or higher.

It also requires RHEL/CentOS 7.4 or higher since OverlayFS support for SELinux has been added in that version.

Role Variables

Variables in defaults/main.yml:

Name	Type	Description
docker_enable	boolean	Indicates whether the role is enabled.
docker_storage_driver	string	Storage driver to be used with Docker. It can be one of the following: overlay2: Use OverlayFS. devicemapper: Use Device Mapper kernel framework. "": Don't do any storage setup with docker-storage-setup. NOTE: The overlay storage driver is omitted since overlay2 is more performant.
docker_storage_volumegroup	string	Name of the LVM volume group to use for Docker storage. NOTE: If the value is "", the role will not configure Docker storage's volume group. NOTE: This variable must be changed from the default value if the docker_storage_driver variable is set to devicemapper.
docker_sudo_users	list	List of users for which to configure passwordless sudo access for running Docker of the form: name: string test (optional): boolean where name represents user's name and test indicates whether to test that convenience alias for running Docker works (defaults to true).
docker_private_registries	list	List of private Docker registries with which to authenticate the current system user of the form: registry_url: string username: string password: string email: string where registry_url (optional) represents registry's URL, username represents user name with which to authenticate with the registry, password represents the user's password and email (optional) represents the user's email address. NOTE: email is required when authenticating with Docker Hub.

Dependencies

None.

Example Playbook

- hosts: all

  vars:
    docker_storage_volumegroup: dockervg
    docker_sudo_users:
      - alice
      - bob

  roles:
    - docker

License

GPLv3

Author Information

Tadej Janež