Docker Swarm is still one of the clearest ways to teach container clustering.

Kubernetes won the mindshare war, but Swarm remains useful because the concepts are visible: managers, workers, services, replicas, overlay networking, and rolling updates. For a small lab or a teaching environment, that simplicity is a feature.

The original Auzietek article had a playful “surfer” voice. The cleaned-up version keeps the approachable spirit while making the steps easier to reuse.

Start with minimal hosts

Use small Linux installs. Keep them boring.

sudo apt update
sudo apt install -y ca-certificates curl gnupg

For Debian or Ubuntu, install Docker from the upstream repository or from your distribution repository depending on how tightly you need version control.

curl -fsSL https://download.docker.com/linux/debian/gpg \
  | sudo gpg --dearmor -o /usr/share/keyrings/docker.gpg

echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker.gpg] \
https://download.docker.com/linux/debian trixie stable" \
  | sudo tee /etc/apt/sources.list.d/docker.list

sudo apt update
sudo apt install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

Initialize the manager

On the first manager:

docker swarm init --advertise-addr 10.20.0.51

Docker returns join commands for workers and additional managers. Save those in your operational notes or, better, in a secure deployment fragment.

docker swarm join-token worker
docker swarm join-token manager

Join workers

On each worker:

docker swarm join --token SWMTKN-... 10.20.0.51:2377

Then validate from a manager:

docker node ls

Deploy a small service

Start with something boring:

docker service create \
  --name hello \
  --replicas 3 \
  --publish 8080:80 \
  nginx:alpine

Check placement:

docker service ls
docker service ps hello
curl -I http://10.20.0.51:8080/

Compose becomes stack

The useful leap is from docker compose to docker stack deploy:

docker stack deploy -c docker-compose.yml demo
docker stack services demo
docker stack ps demo

That maps cleanly to BKC because a pipeline can render a Compose file, ship it, deploy it as a stack, and validate the service URLs.

Operational caveats

• Managers need stable addresses.
• Overlay networks require the Swarm control ports to be reachable.
• Persistent volumes need a plan.
• Published ports should be intentional.
• Secrets should not be baked into images or committed to Git.

The practical conclusion: Swarm is not the whole future of container orchestration, but it remains an excellent “first cluster” and a reliable lab target for teaching infrastructure automation.

Companion example: Docker Swarm for small teams.