Swarm and container networks
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
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.
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