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Lab 23: Connecting to Docker Swarm Manager & Workers and Joining the Cluster

Objective

By the end of this section you will:

  • Initialize Docker Swarm on the manager node.
  • Connect worker nodes to the manager.
  • Verify that the cluster is up and running.
  • Continue with service creation, scaling, and updating.

Initialize the Swarm on the Manager Node

  1. Open PuTTY.

  2. In the Host Name (or IP address) box, enter the Public IP of the Manager node.

  3. Example: 3.110.25.200

  4. In Connection → Data, set the login username to ubuntu (for Ubuntu AMI).

  5. In Connection → SSH → Auth, browse to your private key (.ppk) file.

  6. If you only have .pem from AWS, first convert it to .ppk using PuTTYgen.

  7. Click Open → accept the warning → log in.
  8. Once logged in, run:
docker swarm init --advertise-addr <manager_private_ip>

Replace <manager_private_ip> with the private IP address of the manager (shown in AWS console). Example:

docker swarm init --advertise-addr 10.0.1.10
  1. Open Windows Terminal
  2. Navigate to the folder with your AWS key (.pem). Example:

cd C:\Users\YourName\Downloads
3. Connect to the Manager using SSH:

ssh -i mykey.pem ubuntu@<manager_public_ip>

Example:

ssh -i mykey.pem ubuntu@3.110.25.200
4. Once logged in, run:

docker swarm init --advertise-addr <manager_private_ip>

Example:

docker swarm init --advertise-addr 10.0.1.10

✅ Output: You will see a message like this:

Swarm initialized: current node (abcd1234...) is now a manager.

To add a worker to this swarm, run the following command:

    docker swarm join --token SWMTKN-1-xyz <manager_private_ip>:2377

👉 Copy the entire docker swarm join command. You’ll use it on the worker nodes.

Add Worker Nodes to the Swarm

  1. Open PuTTY again.
  2. Enter the Public IP of Worker 1.
  3. Set username to ubuntu.
  4. Load the same private key .ppk as before.
  5. Connect and log in.
  6. Run the join command you copied from the Manager:
docker swarm join --token SWMTKN-1-xyz 10.0.1.10:2377

Repeat the same process for Worker 2 (and any additional workers).

  1. From PowerShell, connect to Worker 1:

ssh -i mykey.pem ubuntu@<worker1_public_ip>
2. Run the join command:

docker swarm join --token SWMTKN-1-xyz 10.0.1.10:2377
3. Repeat for Worker 2:

ssh -i mykey.pem ubuntu@<worker2_public_ip>
docker swarm join --token SWMTKN-1-xyz 10.0.1.10:2377

Verify Nodes on the Manager

Reconnect to the Manager node (PuTTY or SSH) and run:

docker node ls

✅ You should see:

  • 1 Manager (Leader).
  • 2 Workers (Ready).

Example:

ID                            HOSTNAME   STATUS   AVAILABILITY   MANAGER STATUS   ENGINE VERSION
abcd1234efgh                  manager1   Ready    Active         Leader           24.0.7
ijkl5678mnop                  worker1    Ready    Active                          24.0.7
qrst9012uvwx                  worker2    Ready    Active                          24.0.7