Parameters

The DOCKER module provides 8 configuration parameters.

Parameter Overview

Use the DOCKER parameter group to deploy and configure the Docker container engine. It controls the 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

Specifies whether to enable Docker on the current node. The default is false, which disables Docker.

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, we recommend its mount point for this directory.

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. Set it to cgroupfs or systemd. The default is 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:

docker_registry_mirrors:                        # Choose one or more
  - 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 [].

During installation, Docker automatically pulls the images specified here.

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.

Use docker save | gzip to package images. Set this parameter to import those images automatically during Docker installation.

Docker imports each .tgz tarball that matches this pattern with the following command:

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