Network inspection and debugging in Docker - Mini Project: Build & Apply

Network inspection and debugging

📖 Scenario: You are working on a small Docker project where multiple containers communicate over a custom network. You want to inspect the network and debug connectivity issues between containers.

🎯 Goal: Learn how to create a Docker network, run containers attached to it, inspect the network details, and check container connectivity using Docker commands.

📋 What You'll Learn

Create a custom Docker network named my_custom_net

Run two containers named web and db attached to my_custom_net

Inspect the network my_custom_net to see connected containers

Use Docker commands to check connectivity between web and db

💡 Why This Matters

🌍 Real World

Docker networks help isolate and connect containers in real projects, making sure services can talk to each other securely and efficiently.

💼 Career

Understanding Docker networking and debugging is essential for DevOps roles to troubleshoot container communication issues and maintain healthy deployments.

1

Create a custom Docker network

Create a Docker network called my_custom_net using the docker network create command.

Docker

# Create a Docker network named my_custom_net
# Your code here

Need a hint?

Use the command docker network create my_custom_net to create the network.

2

Run two containers attached to the custom network

Run two containers named web and db using the alpine image. Attach both containers to the my_custom_net network. Use the docker run command with --name and --network options. Run the containers in detached mode with -d.

Docker

docker network create my_custom_net
# Run container named web attached to my_custom_net
# Your code here

Need a hint?

Use docker run -d --name web --network my_custom_net alpine sleep 1000 and similarly for db.

3

Inspect the Docker network to see connected containers

Use the docker network inspect my_custom_net command to view details of the network and verify that both web and db containers are connected.

Docker

docker network create my_custom_net
docker run -d --name web --network my_custom_net alpine sleep 1000
docker run -d --name db --network my_custom_net alpine sleep 1000
# Inspect the network my_custom_net
# Your code here

Need a hint?

Use docker network inspect my_custom_net to see the network details.

4

Check connectivity between containers

Use the docker exec command to run a ping from the web container to the db container by its container name. Use docker exec web ping -c 3 db to send 3 ping packets.

Docker

docker network create my_custom_net
docker run -d --name web --network my_custom_net alpine sleep 1000
docker run -d --name db --network my_custom_net alpine sleep 1000
docker network inspect my_custom_net
# Ping db from web container
# Your code here

Need a hint?

Use docker exec web ping -c 3 db to test connectivity.