[Docker] Allow Containers to Communicate through Docker Networks

Docker containers that are running on your local machine can't communicate with each other. In this mini post explains why and shows a demonstration of Docker networks.

Create two containers:

docker run -it -d --rm --name one alpine /bin/sh
docker run -it -d --rm --name two alpine /bin/sh  

// -it -d: run in interactive mode and in background
// once container is running, enter /bin/sh mode
// use apline as base image 

Entering 'one' container and run /bin/sh

docker exec -it one /bin/sh

If you try to ping container 'two', you will get a bad address error, because two containers are isolated.

ping two

Run:

exit
docker stop one
docker stop two

In order to let two container talk to each other, we need 'network':

docker network create alpine-network

Add two containers into network:

docker run -it -d --rm --name one --network alpine-network alpine /bin/sh
docker run -it -d --rm --name two --network alpine-network alpine /bin/sh

You can see the configurations:

docker network inspect alpine-network

Entering one container:

docker exec -it one /bin/sh
ping two

Now two container should be able to communicate each other