How to Build a Docker Swarm Cluster on Three Ubuntu Nodes Step‑by‑Step

Setup Base Environment

Create three virtual machines (or physical hosts) and install Ubuntu 16.04 Server amd64 . Enable SSH for remote access, install Docker, optionally set up a private Docker Registry, and enable root login.

Configure Nodes

All subsequent operations are performed as the root user on each node (manager0, node0, node1).

Upgrade system packages:

apt-get update && apt-get -y upgrade && apt-get -y install curl

Install Docker Engine: curl -sSL https://get.docker.com/ | sh Start Docker Engine listening on port 2375 (required for Swarm communication):

docker daemon -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock

Configure Consul Discovery Backend

On the manager node, pull the Consul image and start it as a bootstrap server:

docker pull progrium/consul

docker run -d -p 8500:8500 --name=consul progrium/consul -server -bootstrap

Create Swarm Cluster

Create the manager (Swarm control plane) and bind it to the Consul service:

docker run -d -p 4000:4000 swarm manage -H :4000 --replication --advertise 192.168.2.56:4000 consul://192.168.2.56:8500

Note: manager0 also runs the Consul backend, so the advertise IP is the same.

Join the worker nodes to the cluster:

# node0 (IP 192.168.2.77)
 docker run -d swarm join --advertise 192.168.2.77:2375 consul://192.168.2.56:8500

# node1 (IP 192.168.2.129)
 docker run -d swarm join --advertise 192.168.2.129:2375 consul://192.168.2.56:8500

Verify the cluster status:

docker -H :4000 info

Use the Cluster

Run a container on the swarm via the manager: docker -H :4000 run hello-world Repeated runs distribute containers across the two worker nodes, balancing the load.

Common management commands (note the -H :4000 flag to target the swarm):

# List containers on the cluster
 docker -H :4000 ps

# Remove a container
 docker -H :4000 rm -f <em>ContainerID</em>

# Start / stop / restart a container
 docker -H :4000 start <em>ContainerID</em>
 docker -H :4000 stop <em>ContainerID</em>
 docker -H :4000 restart <em>ContainerID</em>

The only difference from direct Docker commands is the addition of -H :4000 to point to the Swarm manager.