Let's see how we can get containers to talk to each other over a Docker network.

Create a Network

We can create a network for containers to be added to:

# List networks
docker network ls

# Create a network
docker network create appnet

Then we can add containers to that network as we run them:

docker run --rm -d \
    --name=app \
    --network=appnet\
     shippingdocker/app:latest

docker run --rm -d \
    --name=mysql \
    --network=appnet \
    -e MYSQL_ROOT_PASSWORD=root \
    -e MYSQL_DATABASE=homestead \
    -e MYSQL_USER=homestead \
    -e MYSQL_USER_PASSWORD=secret \
    mysql:5.7

This creates two containers (see the videos for details on the MySQL container), and adds them into the new network appnet.

The containers then can reference eachother - the hostname for each container is taken from the --name given to the container. This lets the app container talk to mysql over hostname mysql.

Within a container, you can run getent hosts mysql to see the hostname resolution of hostname mysql.