2. Docker swarm setup

Overview

This section provides a step-by-step guide to setting up Docker Swarm on your system, including initializing the Swarm, adding nodes, and verifying the setup.

Prerequisites

Ensure Docker is installed on all machines intended for the Swarm (both manager and worker nodes). Networking configurations between nodes should allow for communication on ports Docker Swarm uses (e.g., TCP 2377, 7946, and UDP 4789).

Steps

Initialize Docker Swarm

docker swarm init --advertise-addr <MANAGER_IP>

The --advertise-addr option provides the IP address that Docker Swarm will use to connect with other nodes. This is particularly useful if your system has numerous network interfaces, such as in a cloud environment or a network that uses both public and private IP addresses.

Add Worker Nodes to the Swarm

docker swarm join --token <JOIN_TOKEN> <MANAGER_IP>:2377

Replace <JOIN_TOKEN> and <MANAGER_IP> with the values from the docker swarm init output. The IP address <MANAGER_IP> should match the --advertise-addr IP you specified when initializing the Swarm.

If the docker swarm init output was cleared, you can retrieve the join token at any time from the manager node.

docker swarm join-token worker

Verifying the Swarm Cluster

docker node ls