observability.svc.plus/roles/docker/README.md

Role: docker

Deploy Docker Container Runtime

Module	DOCKER
Docs	https://pigsty.io/docs/docker/
Related Roles	node, infra

Overview

The docker role installs Docker container runtime on nodes:

• Install Docker CE and docker-compose plugin
• Add admin user to docker group
• Create data directory
• Configure Docker daemon (registry mirrors, storage driver)
• Launch Docker service
• Register to monitoring
• Load cached Docker images (optional)

Docker is used to run stateless applications alongside Pigsty.

Playbooks

Playbook	Description
docker.yml	Deploy Docker

File Structure

roles/docker/
├── defaults/
│   └── main.yml              # Default variables
├── meta/
│   └── main.yml              # Role dependencies
├── tasks/
│   └── main.yml              # Main task list
└── templates/
    └── daemon.json.j2        # Docker daemon config

Tags

Tag Hierarchy

docker (full role)
│
├── docker_install             # Install Docker packages
│
├── docker_admin               # Add admin to docker group
│
├── docker_dir                 # Create data directory
│
├── docker_config              # Configure daemon.json
│
├── docker_launch              # Start Docker service
│
├── docker_register            # Register to monitoring
│   └── add_metrics            # Add Victoria targets
│
└── docker_image               # Load Docker images

Key Variables

Basic Configuration

Variable	Default	Description
docker_enabled	false	Enable Docker on this node
docker_data	/data/docker	Docker data directory

Storage & Runtime

Variable	Default	Description
docker_storage_driver	overlay2	Storage driver (overlay2/zfs/btrfs)
docker_cgroups_driver	systemd	Cgroup driver (systemd/cgroupfs)

Registry

Variable	Default	Description
docker_registry_mirrors	[]	Registry mirror URLs

Monitoring

Variable	Default	Description
docker_exporter_port	9323	Docker metrics exporter port

Images

Variable	Default	Description
docker_image	[]	Images to pull after install
docker_image_cache	/tmp/docker/*.tgz	Local image cache glob pattern

Enabling Docker

Docker is disabled by default. Enable per-node or per-cluster:

# Enable for specific node
infra:
  hosts:
    10.10.10.10:
      docker_enabled: true

# Enable for entire cluster
infra:
  vars:
    docker_enabled: true

Registry Mirrors

Configure registry mirrors for faster pulls:

docker_registry_mirrors:
  - https://mirror.gcr.io
  - https://registry.docker-cn.com

Pre-loading Images

Pull from Registry

docker_image:
  - grafana/grafana:latest
  - prom/prometheus:latest

Load from Local Cache

Place .tgz image archives in /tmp/docker/:

# Save image to cache
docker save grafana/grafana:latest | gzip > /tmp/docker/grafana.tgz

Daemon Configuration

The role generates /etc/docker/daemon.json:

{
  "data-root": "/data/docker",
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": { "max-size": "100m" },
  "storage-driver": "overlay2",
  "metrics-addr" : "0.0.0.0:9323",
  "experimental" : true,
  "max-concurrent-downloads": 8,
  "registry-mirrors" : []
}

See Also

• node: Node provisioning
• infra: Infrastructure deployment
• Docker Guide: Configuration documentation