Swarm and container networks
Estimated reading time: 3 minutesYou are viewing docs for legacy standalone Swarm. These topics describe standalone Docker Swarm. In Docker 1.12 and higher, Swarm mode is integrated with Docker Engine. Most users should use integrated Swarm mode — a good place to start is Getting started with swarm mode, Swarm mode CLI commands, and the Get started with Docker walkthrough). Standalone Docker Swarm is not integrated into the Docker Engine API and CLI commands.
Docker Swarm is fully compatible with Docker’s networking features. This includes the multi-host networking feature which allows creation of custom container networks that span multiple Docker hosts.
Before using Swarm with a custom network, read through the conceptual information in Docker container networking. You should also have walked through the Get started with multi-host networking example.
Create a custom network in a Swarm cluster
Multi-host networks require a key-value store. The key-value store holds information about the network state which includes discovery, networks, endpoints, IP addresses, and more. Through the Docker’s libkv project, Docker supports Consul, Etcd, and ZooKeeper key-value store backends. For details about the supported backends, refer to the libkv project.
To create a custom network, you must choose a key-value store backend and
implement it on your network. Then, you configure the Docker Engine daemon to
use this store. Two required parameters, --cluster-store and
--cluster-advertise, refer to your key-value store server.
Once you’ve configured and restarted the daemon on each Swarm node, you are ready to create a network.
List networks
This example assumes there are two nodes node-0 and node-1 in the cluster.
From a Swarm node, list the networks:
$ docker network ls
NETWORK ID NAME DRIVER
3dd50db9706d node-0/host host
09138343e80e node-0/bridge bridge
8834dbd552e5 node-0/none null
45782acfe427 node-1/host host
8926accb25fd node-1/bridge bridge
6382abccd23d node-1/none null
As you can see, each network name is prefixed by the node name.
Create a network
By default, Swarm is using the overlay network driver, a global-scope network
driver. A global-scope network driver creates a network across an entire Swarm cluster.
When you create an overlay network under Swarm, you can omit the -d option:
$ docker network create swarm_network
42131321acab3233ba342443Ba4312
$ docker network ls
NETWORK ID NAME DRIVER
3dd50db9706d node-0/host host
09138343e80e node-0/bridge bridge
8834dbd552e5 node-0/none null
42131321acab node-0/swarm_network overlay
45782acfe427 node-1/host host
8926accb25fd node-1/bridge bridge
6382abccd23d node-1/none null
42131321acab node-1/swarm_network overlay
As you can see here, both the node-0/swarm_network and the
node-1/swarm_network have the same ID. This is because when you create a
network on the cluster, it is accessible from all the nodes.
To create a local scope network (for example with the bridge network driver) you
should use <node>/<name> otherwise your network is created on a random node.
$ docker network create node-0/bridge2 -b bridge
921817fefea521673217123abab223
$ docker network create node-1/bridge2 -b bridge
5262bbfe5616fef6627771289aacc2
$ docker network ls
NETWORK ID NAME DRIVER
3dd50db9706d node-0/host host
09138343e80e node-0/bridge bridge
8834dbd552e5 node-0/none null
42131321acab node-0/swarm_network overlay
921817fefea5 node-0/bridge2 bridge
45782acfe427 node-1/host host
8926accb25fd node-1/bridge bridge
6382abccd23d node-1/none null
42131321acab node-1/swarm_network overlay
5262bbfe5616 node-1/bridge2 bridge
--opt encrypted is a feature only available in Docker Swarm mode. It’s not supported in Swarm standalone.
Network encryption requires key management, which is outside the scope of Swarm.
Remove a network
To remove a network you can use its ID or its name. If two different networks
have the same name, include the <node> value:
$ docker network rm swarm_network
42131321acab3233ba342443Ba4312
$ docker network rm node-0/bridge2
921817fefea521673217123abab223
$ docker network ls
NETWORK ID NAME DRIVER
3dd50db9706d node-0/host host
09138343e80e node-0/bridge bridge
8834dbd552e5 node-0/none null
45782acfe427 node-1/host host
8926accb25fd node-1/bridge bridge
6382abccd23d node-1/none null
5262bbfe5616 node-1/bridge2 bridge
The swarm_network was removed from every node. The bridge2 was removed only
from node-0.