Docker

Setup Docker, provides options for using an advanced storage or networking configuration. Installs the latest official upstream Docker (Community Edition).

This role should work with RedHat Enterprise Linux 7, but this is not supported by Docker.

If you want the distribution supplied Docker package do not use this role.

Role Variables

Optional variables:

• docker_version: Install a particular version of docker, e.g. 17.12.1.ce-1.el7.centos, default current
• docker_groupmembers: A list of users who will be added to the docker system group, allows docker to be run without sudo
• docker_use_ipv4_nic_mtu: Force Docker to use the MTU set by the main IPV4 interface. This may be necessary on virtualised hosts, see comment in defaults/main.yml.
• docker_additional_options: Dictionary of additional Docker configuration options.
• docker_use_custom_storage: If True use a custom storage configuration, default False
• docker_use_custom_network: If True use a custom network configuration, default False
• docker_systemd_setup: Set this to False to disable automatic systemd configuration, default False. You may wish to use this when building virtualisation images.
• docker_repo_force_releasever: The repo config uses the $releasever variables. On some systems this may not work, if necessary you can forcibly override it by setting this variable.

Custom storage

If docker_use_custom_storage is True thin-pool logical volumes will be created for Docker, and a separate logical volume will be created for the Docker volume (/var/lib/docker).

• docker_basefs: Filesystem to use for the Docker containers (default xfs)
• docker_lvfilesystem: Filesystem for the Docker volume (default xfs)
• docker_lvopts: Additional arguments to be used when creating logical volumes

The following variables must be defined when using custom storage:

• docker_vgname: LVM volume group for the logical volumes
• docker_poolsize: Size of the Docker thin-pool partition
• docker_metadatasize: Size of the Docker thin-pool metadata partition (try 1% of the poolsize)
• docker_volumesize: Size of the Docker volume

If docker_use_custom_storage is False you may wish to mount /var/lib/docker on a separate partition or volume before applying this role.

Custom networking

If docker_use_custom_network is True a custom network bridge will be used, this must be created outside of this role. The following variables must be defined:

• docker_bridge_name: The name of a custom network bridge for docker
• docker_bridge_ips: The custom IP range that docker should use for allocating IPs

Dependencies

Depends on lvm-partition.

Development

This role is partially tested by Travis-CI, which requires running Docker-in-Docker. When testing changes you should therefore run a full test using molecule with the Vagrant driver as part of any review:

molecule test --driver vagrant

Example Playbook

Simple example (uses default storage overlay driver):

- hosts: localhost
  roles:
    - role: ome.docker

Example using the default storage driver, with a dedicated logical volume for docker:

- hosts: localhost
  roles:
    - role: ome.lvm_partition
      lvm_lvname: var_lib_docker
      lvm_lvmount: /var/lib/docker
      lvm_lvsize: 100g
      lvm_lvfilesystem: ext4
    - role: ome.docker

Advanced example using custom storage and listening on external port 4243 (insecure). The LVM volume group VolGroup00 must already exist:

- hosts: localhost
  roles:
    - role: ome.docker
      docker_use_ipv4_nic_mtu: True
      docker_use_custom_storage: True
      docker_vgname: VolGroup00
      docker_poolsize: 10g
      docker_metadatasize: 100m
      docker_volumesize: 5g
      docker_groupmembers: [centos]
      docker_additional_options:
        hosts:
          - tcp://0.0.0.0:4243
          - unix:///var/run/docker.sock

Author Information

ome-devel@lists.openmicroscopy.org.uk