Overlay networks in Swarm in Docker - Mini Project: Build & Apply

Overlay networks in Swarm

📖 Scenario: You are setting up a Docker Swarm cluster to run multiple services that need to communicate securely across different nodes. To enable this, you will create an overlay network that spans all nodes in the swarm.

🎯 Goal: Learn how to create an overlay network in Docker Swarm and attach services to it for cross-node communication.

📋 What You'll Learn

Create a Docker overlay network named my_overlay

Create a service named web attached to my_overlay

Create a service named db attached to my_overlay

Verify the services are running and connected to the overlay network

💡 Why This Matters

🌍 Real World

Overlay networks in Docker Swarm let multiple containers communicate securely across different physical or virtual machines, useful for scalable microservices.

💼 Career

Understanding overlay networks is essential for DevOps roles managing container orchestration and multi-host networking in production environments.

1

Initialize Docker Swarm

Run the command docker swarm init to initialize the current node as a swarm manager.

Docker

# Run the command to initialize Docker Swarm
# Your code here

Need a hint?

Use docker swarm init to start the swarm on your current machine.

2

Create an overlay network

Create an overlay network named my_overlay using the command docker network create --driver overlay my_overlay.

Docker

docker swarm init
# Create an overlay network named my_overlay
# Your code here

Need a hint?

Use docker network create --driver overlay my_overlay to create the overlay network.

3

Deploy services attached to the overlay network

Create two services: web running the nginx image and db running the redis image. Attach both services to the my_overlay network using --network my_overlay.

Docker

docker swarm init
docker network create --driver overlay my_overlay
# Create service web attached to my_overlay
# Create service db attached to my_overlay
# Your code here

Need a hint?

Use docker service create --name web --network my_overlay nginx and similarly for the db service.

4

Verify services and network connectivity

Run docker service ls to list the running services and docker network inspect my_overlay to check that the services are connected to the overlay network.

Docker

docker swarm init
docker network create --driver overlay my_overlay
docker service create --name web --network my_overlay nginx
docker service create --name db --network my_overlay redis
# List running services
# Inspect the my_overlay network
# Your code here

Need a hint?

Use docker service ls and docker network inspect my_overlay to verify.