Docker Networking Basics
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.
- Task 1 - The
docker networkcommand - Task 2 - List networks
- Task 3 - Inspect a network
- Task 4 - List network driver plugins
- Task 5 - Create Network
- Task 6 - Remove Network
Prerequisites
You will need all of the following to complete this lab:
- A Linux-based Docker Host running Docker 1.12 or higher
Task 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.
Task 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.
Task 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.
Task 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.
Task 5: Create Network
Now we will provision our own network called my-network with the following configuration
--driver - indicated the network driver to utilize for the network
--internal - configures the network as an internal private network with no internet access
--subnet- define the subnet of the network
--ip-range - IP range available to the containers on this network
--gateway- Network gateway to be used
$ docker network create \
--driver bridge \
--internal \
--subnet=172.28.0.0/16 \
--ip-range=172.28.5.0/24 \
--gateway=172.28.5.254 \
my-network
d6b825e0fb2d96f13719affc3e7658df2c9dc70ccfb4b9e6405348a1624e5d4b
Let’s have a look at out newly created network
docker network ls
NETWORK ID NAME DRIVER SCOPE
4504287a8cd2 bridge bridge local
c6282c586073 docker_gwbridge bridge local
f0d518128cc6 host host local
18789d70fb40 my-network bridge local
f806d1a20208 none null local
Now, inspect my-network
$ docker network inspect my-network
[
{
"Name": "my-network",
"Id": "09aefb1784bc64cd8ad9ef1e3a2132fa0812137b1ff8477c73eeb3050f9dcc21",
"Created": "2019-12-02T10:04:43.300611371Z",
"Scope": "local",
"Driver": "bridge",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": {},
"Config": [
{
"Subnet": "172.28.0.0/16",
"IPRange": "172.28.5.0/24",
"Gateway": "172.28.5.254"
}
]
},
"Internal": true,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {},
"Options": {},
"Labels": {}
}
]
Task 6: Delete Network
Cleanup the newly create my-network
$ docker network rm my-network
Next Steps, Web Apps
For the next step in the tutorial, head over to Webapps with Docker