Demo Overlay Network

In this tutorial, you'll learn how to create a custom Docker overlay network, deploy services in both ingress and host publish modes, and clean up all resources. This is essential for scalable, multi-host deployments in Docker Swarm.

1. List Existing Docker Networks

Start by checking the current Docker networks on your Swarm manager:

docker network ls

Example output:

NETWORK ID     NAME                DRIVER    SCOPE
a57b5746ed31   bridge              bridge    local
b407178964ed3  docker_gwbridge     bridge    local
b8a3f6b8b75    host                host      local
iudyepxwd79a   ingress             overlay   swarm
02733bc831dd   none                null      local

Docker Swarm mode automatically creates two additional networks:

2. Create a Custom Overlay Network

Overlay networks enable containers across multiple Docker hosts to communicate. To create a custom network named kodekloudnet, run:

docker network create \
  --driver overlay \
  kodekloudnet

Verify the new network appears in the list:

docker network ls

Inspect the network’s configuration:

docker network inspect kodekloudnet

Sample JSON output:

[
  {
    "Name": "kodekloudnet",
    "Id": "mr17hw7o7lnos8qyu3ndecv7",
    "Scope": "swarm",
    "Driver": "overlay",
    "IPAM": {
      "Config": [
        {
          "Subnet": "10.0.2.0/24",
          "Gateway": "10.0.2.1"
        }
      ]
    },
    "Attachable": false,
    "Ingress": false
  }
]

docker network create \
  --driver overlay \
  --subnet 10.10.0.0/16 \
  --gateway 10.10.0.1 \
  kodekloudnet

3. Deploy a Service in Ingress Mode

Ingress mode distributes traffic across all nodes on the published port. Even if a task isn’t running on a specific node, it will forward traffic to an active task elsewhere.

docker service create \
  --name ingressservice \
  --publish published=80,target=80 \
  --replicas=2 \
  --network=kodekloudnet \
  yogeshraheja/kodekloudwebimage:v1

• --publish published=80,target=80 uses the Swarm ingress load-balancer.
• Access the application via any manager or worker node IP:
  http://<node-ip>/

4. Deploy a Service in Host Mode

Host mode binds the published port directly on each node where a task is running. Nodes without a task on port 80 will not respond.

docker service create \
  --name hostservice \
  --publish mode=host,published=80,target=80 \
  --replicas=2 \
  --network=kodekloudnet \
  yogeshraheja/kodekloudwebimage:v1

5. Clean Up Resources

When you’re done, remove the services and the custom network:

docker service rm ingressservice hostservice
docker network rm kodekloudnet

Links and References

• Docker Networking Overview
• Docker Swarm Mode
• Overlay Network Driver