Parameters

The DOCKER module provides 8 configuration parameters.

Parameter Overview

The DOCKER parameter group is used for Docker container engine deployment and configuration, including enable switch, data directory, storage driver, registry mirrors, and monitoring.

You can use the docker.yml playbook to install and enable Docker on nodes.

Default parameters are defined in roles/docker/defaults/main.yml

docker_enabled: false             # Enable Docker on current node?
docker_data: /data/docker         # Docker data directory, /data/docker by default
docker_storage_driver: overlay2   # Docker storage driver, overlay2/zfs/btrfs...
docker_cgroups_driver: systemd    # Docker cgroup driver: cgroupfs or systemd
docker_registry_mirrors: []       # Docker registry mirror list
docker_exporter_port: 9323        # Docker metrics exporter port, 9323 by default
docker_image: []                  # Docker images to pull after startup
docker_image_cache: /tmp/docker/*.tgz # Docker image cache tarball glob pattern

docker_enabled

Parameter: docker_enabled, Type: bool, Level: G/C/I

Enable Docker on current node? Default: false, meaning Docker is not enabled.

docker_data

Parameter: docker_data, Type: path, Level: G/C/I

Docker data directory, default is /data/docker.

This directory stores Docker images, containers, volumes, and other data. If you have a dedicated data disk, it’s recommended to point this directory to that disk’s mount point.

docker_storage_driver

Parameter: docker_storage_driver, Type: enum, Level: G/C/I

Docker storage driver, default is overlay2.

See official documentation: https://docs.docker.com/engine/storage/drivers/select-storage-driver/

Available storage drivers include:

• overlay2: Recommended default driver, suitable for most scenarios
• fuse-overlayfs: For rootless container scenarios
• btrfs: When using Btrfs filesystem
• zfs: When using ZFS filesystem
• vfs: For testing purposes, not recommended for production

docker_cgroups_driver

Parameter: docker_cgroups_driver, Type: enum, Level: G/C/I

Docker cgroup filesystem driver, can be cgroupfs or systemd, default: systemd

docker_registry_mirrors

Parameter: docker_registry_mirrors, Type: string[], Level: G/C/I

Docker registry mirror list, default: [] empty array.

You can use Docker mirror sites to accelerate image pulls. Here are some examples:

["https://docker.m.daocloud.io"]                # DaoCloud mirror
["https://docker.1ms.run"]                      # 1ms mirror
["https://mirror.ccs.tencentyun.com"]           # Tencent Cloud internal mirror
["https://registry.cn-hangzhou.aliyuncs.com"]   # Alibaba Cloud mirror (requires login)

You can also consider using a Cloudflare Worker to set up a Docker Proxy for faster access.

If pull speeds are still too slow, consider using alternative registries: docker login quay.io

docker_exporter_port

Parameter: docker_exporter_port, Type: port, Level: G

Docker metrics exporter port, default is 9323.

The Docker daemon exposes Prometheus-format monitoring metrics on this port for collection by monitoring infrastructure.

docker_image

Parameter: docker_image, Type: string[], Level: G/C/I

List of Docker images to pull, default is empty list [].

Docker image names specified here will be automatically pulled during the installation phase.

docker_image_cache

Parameter: docker_image_cache, Type: path, Level: G/C/I

Local Docker image cache tarball glob pattern, default is /tmp/docker/*.tgz.

You can use docker save | gzip to package images and automatically import them during Docker installation via this parameter.

.tgz tarball files matching this pattern will be imported into Docker one by one using:

cat *.tgz | gzip -d -c - | docker load