Docker Networking Basics
Lab Meta
Difficulty: Beginner
Time: Approximately 10 minutes
In this lab you’ll look at the most basic networking components that come with a fresh installation of Docker.
You will complete the following steps as part of this lab.
- Step 1 - The
docker networkcommand - Step 2 - List networks
- Step 3 - Inspect a network
- Step 4 - List network driver plugins
Prerequisites
You will need all of the following to complete this lab:
- A Linux-based Docker Host running Docker 1.12 or higher
Step 1: The docker network command
The docker network command is the main command for configuring and managing container networks.
Run a simple docker network command from any of your lab machines.
$ docker network Usage: docker network COMMAND Manage Docker networks Options: --help Print usage Commands: connect Connect a container to a network create Create a network disconnect Disconnect a container from a network inspect Display detailed information on one or more networks ls List networks rm Remove one or more networks Run 'docker network COMMAND --help' for more information on a command. The command output shows how to use the command as well as all of the docker network sub-commands. As you can see from the output, the docker network command allows you to create new networks, list existing networks, inspect networks, and remove networks. It also allows you to connect and disconnect containers from networks.
Step 2: List networks
Run a docker network ls command to view existing container networks on the current Docker host.
$ docker network ls NETWORK ID NAME DRIVER SCOPE 1befe23acd58 bridge bridge local 726ead8f4e6b host host local ef4896538cc7 none null local The output above shows the container networks that are created as part of a standard installation of Docker.
New networks that you create will also show up in the output of the docker network ls command.
You can see that each network gets a unique ID and NAME. Each network is also associated with a single driver. Notice that the “bridge” network and the “host” network have the same name as their respective drivers.
Step 3: Inspect a network
The docker network inspect command is used to view network configuration details. These details include; name, ID, driver, IPAM driver, subnet info, connected containers, and more.
Use docker network inspect to view configuration details of the container networks on your Docker host. The command below shows the details of the network called bridge.
$ docker network inspect bridge [ { "Name": "bridge", "Id": "1befe23acd58cbda7290c45f6d1f5c37a3b43de645d48de6c1ffebd985c8af4b", "Scope": "local", "Driver": "bridge", "EnableIPv6": false, "IPAM": { "Driver": "default", "Options": null, "Config": [ { "Subnet": "172.17.0.0/16", "Gateway": "172.17.0.1" } ] }, "Internal": false, "Containers": {}, "Options": { "com.docker.network.bridge.default_bridge": "true", "com.docker.network.bridge.enable_icc": "true", "com.docker.network.bridge.enable_ip_masquerade": "true", "com.docker.network.bridge.host_binding_ipv4": "0.0.0.0", "com.docker.network.bridge.name": "docker0", "com.docker.network.driver.mtu": "1500" }, "Labels": {} } ] NOTE: The syntax of the
docker network inspectcommand isdocker network inspect <network>, where<network>can be either network name or network ID. In the example above we are showing the configuration details for the network called “bridge”. Do not confuse this with the “bridge” driver.
Step 4: List network driver plugins
The docker info command shows a lot of interesting information about a Docker installation.
Run a docker info command on any of your Docker hosts and locate the list of network plugins.
$ docker info Containers: 0 Running: 0 Paused: 0 Stopped: 0 Images: 0 Server Version: 1.12.3 Storage Driver: aufs <Snip> Plugins: Volume: local Network: bridge host null overlay <<<<<<<< Swarm: inactive Runtimes: runc <Snip> The output above shows the bridge, host, null, and overlay drivers.