Using Docker Network

Tested Infrastructure

Platform	Number of Instance	Reading Time
Play with Docker	1	5 min

Pre-requisite

Create an account with DockerHub
Open PWD Platform on your browser
Click on Add New Instance on the left side of the screen to bring up Alpine OS instance on the right side

Instructions

Display all the existent networks in the host:

$ docker network ls

Let’s create a new bridge network:

$ docker network create -d bridge my-bridge-network

Run a container linked to the created network:

$ docker run -d -p 8081:8081 -e "port=8081" --name app --network=my-bridge-network selaworkshops/python-app:2.0

Find the container internal ip using:

$ docker inspect app

"Networks": {
                "my-bridge-network": {
                    "IPAMConfig": null,
                    "Links": null,
                    "Aliases": [
                        "cf148e899ea8"
                    ],
                    "NetworkID": "82057fd5c45f1d62b0a96ac905af529ef6715e9f1038e6307f83b6698717dcfa",
                    "EndpointID": "24c5ac91c33c089427cf2f81cdc09c3ee4db09ecc0cb3b8298ba223689c10f4a",
                    "Gateway": "172.21.0.1",
                    "IPAddress": "172.21.0.2",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",
                    "GlobalIPv6PrefixLen": 0,
                    "MacAddress": "02:42:ac:15:00:02",
                    "DriverOpts": null
                }
            }

Write down the IPAddress of “my-bridge-network” (you may have diffrent address than the above)
Open a new terminal windows and run an ubuntu container in interactive mode:

$ docker run -it --name client alpine:latest

Install curl in the client container:

$ apk --no-cache add curl

From the client container terminal try to browse to the app container: (change the IP Address accordingly)

$ curl 172.21.0.2:8081 --connect-timeout 5

You will get no access and the connection will be terminated due to timeout

$ curl: (28) Connection timed out after 5000 milliseconds

From the regular terminal run the command below to attach the client container to the created network:

$ docker network connect my-bridge-network client

From the client container terminal try to browse to the app container again: (change the IP Address accordingly)

$ curl 172.21.0.2:8081 --connect-timeout 5

<h1>Python App</h1>

Inspect the network from the regular terminal and look for the linked containers:

$ docker inspect my-bridge-network

"Containers": {
            "793a39c035a8988c1768f6061f1721ac124293502edb46ed16e06111f9bdbd61": {
                "Name": "client",
                "EndpointID": "1e2b7be275a10962c105fe01a85254ebb69dab33a60b1d9d9bc23bcfef1f337d",
                "MacAddress": "02:42:ac:15:00:03",
                "IPv4Address": "172.21.0.3/16",
                "IPv6Address": ""
            },
            "cf148e899ea8e91d9b12e2f1333bdbb144cebca9e088e6e5bfec63dd48c33ab8": {
                "Name": "app",
                "EndpointID": "24c5ac91c33c089427cf2f81cdc09c3ee4db09ecc0cb3b8298ba223689c10f4a",
                "MacAddress": "02:42:ac:15:00:02",
                "IPv4Address": "172.21.0.2/16",
                "IPv6Address": ""
            }
        },

Disconnect both containers from the created network (regular terminal):

$ docker network disconnect my-bridge-network app
$ docker network disconnect my-bridge-network client

Delete the network:

$ docker network rm my-bridge-network

Ensure that the network was deleted:

$ docker network ls

Exit from the client container and close the terminal:

$ exit
$ exit

Next » Lab #1: Listing the Networks