docker network connect

Estimated reading time: 3 minutes

Description

Connect a container to a network

Usage

docker network connect [OPTIONS] NETWORK CONTAINER

Options

Name, shorthand Default Description
--alias   Add network-scoped alias for the container
--ip   IP Address
--ip6   IPv6 Address
--link   Add link to another container
--link-local-ip   Add a link-local address for the container

Parent command

Command Description
docker network Manage networks
Command Description
docker network connect Connect a container to a network
docker network create Create a network
docker network disconnect Disconnect a container from a network
docker network inspect Display detailed information on one or more networks
docker network ls List networks
docker network prune Remove all unused networks
docker network rm Remove one or more networks

Extended description

Connects a container to a network. You can connect a container by name or by ID. Once connected, the container can communicate with other containers in the same network.

Examples

Connect a running container to a network

$ docker network connect multi-host-network container1

Connect a container to a network when it starts

You can also use the docker run --network=<network-name> option to start a container and immediately connect it to a network.

$ docker run -itd --network=multi-host-network busybox

Specify the IP address a container will use on a given network

You can specify the IP address you want to be assigned to the container’s interface.

$ docker network connect --ip 10.10.36.122 multi-host-network container2

You can use --link option to link another container with a preferred alias

$ docker network connect --link container1:c1 multi-host-network container2

Create a network alias for a container

--alias option can be used to resolve the container by another name in the network being connected to.

$ docker network connect --alias db --alias mysql multi-host-network container2

Network implications of stopping, pausing, or restarting containers

You can pause, restart, and stop containers that are connected to a network. A container connects to its configured networks when it runs.

If specified, the container’s IP address(es) is reapplied when a stopped container is restarted. If the IP address is no longer available, the container fails to start. One way to guarantee that the IP address is available is to specify an --ip-range when creating the network, and choose the static IP address(es) from outside that range. This ensures that the IP address is not given to another container while this container is not on the network.

$ docker network create --subnet 172.20.0.0/16 --ip-range 172.20.240.0/20 multi-host-network
$ docker network connect --ip 172.20.128.2 multi-host-network container2

To verify the container is connected, use the docker network inspect command. Use docker network disconnect to remove a container from the network.

Once connected in network, containers can communicate using only another container’s IP address or name. For overlay networks or custom plugins that support multi-host connectivity, containers connected to the same multi-host network but launched from different Engines can also communicate in this way.

You can connect a container to one or more networks. The networks need not be the same type. For example, you can connect a single container bridge and overlay networks.

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