Docker Swarm

Docker Swarm is a native clustering and orchestration solution for Docker. It enables the creation and management of a swarm of Docker nodes, turning them into a single, virtual Docker host. Docker Swarm allows you to deploy and manage containerized applications across a cluster of machines, providing high availability, scalability, and ease of use.

Getting started

1. Initialize a Swarm on a manager node:

docker swarm init

2. Join additional nodes to the Swarm:

docker swarm join --token <token> <manager-ip>

3. Deploy a service Here’s an example Docker Compose file for a simple web service:

version: '3'
 
services:
  web:
    image: nginx
    ports:
      - "80:80"
    deploy:
      replicas: 3

Deploy this service using:

docker stack deploy -c docker-compose.yml myapp

docker swarm

Manage Swarm

docker swarm ca

Display and rotate the root CA Usage:

# Display Cert
docker swarm ca
 
# Rotate cert
docker swarm ca --rotate

docker swarm init

Initialize a swarm Usage: docker swarm init --advertise-addr IP

docker swarm join-token

Manage join tokens Usage: docker swarm join-token [--rotate] (worker|manager)

docker swarm join

Join a swarm as a node and/or manager Usage: docker swarm join [--token token] HOST:PORT

docker swarm leave

Leave the swarm Usage: docker swarm leave [-f, --force]

docker node

Manage Swarm nodes

docker node demote

Demote one or more nodes from manager in the swarm Usage: docker node demote NODE [NODE...]

docker node ls

List nodes in the swarm Usage: docker node ls [--format json] [-f, --filter FILTER=VALUE]

The currently supported filters are:

• id
• label
• node.label
• membership
• name
• role

docker node promote

Promote one or more nodes to manager in the swarm Usage: docker node promote NODE [NODE...]

docker node ps

List tasks running on one or more nodes, defaults to current node Usage: docker node ps [--format json] [NODE...]

docker node rm

Remove one or more nodes from the swarm Usage: docker node rm [-f, --force] NODE [NODE...]

docker node update

Update metadata about a node, such as its availability, labels, or roles. Usage: docker node update [OPTIONS] NODE

Options

Option	Description
--availability state	Availability of the node (active, pause, drain)
--label-add key=value	Add or update a node label
--label-rm key	Remove a node label if exists
--role role	Role of the node (worker, manager)

docker service

These commands apply to services and are almost identical to container commands.

docker service create [OPTIONS] IMAGE [COMMAND] [ARG...]
docker service logs [OPTIONS] SERVICE|TASK
docker service ls [OPTIONS]
docker service ps [OPTIONS] SERVICE [SERVICE...]
docker service rm SERVICE [SERVICE...]
docker service scale SERVICE=REPLICAS [SERVICE=REPLICAS...]

docker stack

Manage Swarm stacks. This command works on a swarm orchestrator.

docker stack deploy

Deploy a new stack or update an existing stack Usage: docker stack deploy [OPTIONS] STACK

Options

Option	Description
-c, --compose-file file	Path to a Compose file, or - to read from stdin
--prune	Prune services that are no longer referenced
--with-registry-auth	Send registry authentication details to Swarm agents

docker stack ls

List stacks Usage: docker stack ls [--format json]

docker stack ps

List the tasks in the stack Usage: docker stack ps [--format json]

docker stack rm

Remove one or more stacks Usage: docker stack rm STACK [STACK...]

docker stack services

List the services in the stack Usage: docker stack services [--format json] STACK