Networks

Open a Platform, then Networks to inspect or create Docker networks. Containers use networks to communicate; publishing a container port separately makes that port reachable through the Docker host.

Create a network

You need an online Platform and permission to create networks.

1. Select Add Network and enter a name, such as app-network.
2. For Docker Standalone, keep Bridge for a typical application network.
3. Leave address allocation at its defaults unless you need a particular subnet or gateway. If you specify a subnet, avoid overlap with existing networks.
4. Select Save and check that the network appears in the list.

On Swarm, choose Swarm scope and Overlay for a cluster network. Local manager scope creates a network only on the connected manager. Enable Attachable when standalone containers also need to join an overlay network.

Use the network

For a Deployment, select the network in its configuration, save, and deploy or redeploy. Creating the network alone does not attach an existing container.

For a Stack, Compose can create its own networks. To use the network you created above, declare it as external and attach the service:

services:
  web:
    image: nginx:alpine
    networks:
      - app-network

networks:
  app-network:
    external: true

This example joins a network without publishing a host port. Add a port mapping or connect your reverse proxy when the application needs access from outside it.

Inspect or remove a network

Use Inspect to review the driver, address allocation, and attached containers. If applications cannot communicate, check that they share the intended network and use the application's container port.

Delete is unavailable for system networks, networks in use, and Node-specific network inventory. Remove workload references and redeploy affected workloads before deleting an unused network. For Swarm, also check Service attachments.

Citadel's network form creates networks; it does not edit an existing network's configuration. Create a replacement when its settings need to change.