Debugging network issues in Docker - Mini Project: Build & Apply

Debugging network issues

📖 Scenario: You are working with Docker containers that need to communicate with each other on a custom network. Sometimes, containers cannot reach each other due to network misconfiguration. You want to set up a simple Docker network and containers, then check their connectivity to debug network issues.

🎯 Goal: Build a Docker setup with a custom network and two containers. Then, use Docker commands to check if the containers can ping each other, helping you understand and debug network connectivity problems.

📋 What You'll Learn

Create a custom Docker network named my_network

Run two containers named container1 and container2 attached to my_network

Use the alpine image for both containers

Check connectivity by pinging container2 from container1

Print the ping command output to verify connectivity

💡 Why This Matters

🌍 Real World

Docker containers often need to communicate in microservices or multi-container apps. Debugging network issues ensures services can talk to each other reliably.

💼 Career

DevOps engineers and developers use Docker networking daily to deploy and troubleshoot containerized applications in production and development.

1

Create a custom Docker network

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

Docker

# Your code here

Need a hint?

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

2

Run two containers on the custom network

Run two containers named container1 and container2 using the alpine image. Attach both containers to the my_network network. Use the docker run command with --network my_network and --name options.

Docker

docker network create my_network
# Your code here

Need a hint?

Use docker run -dit --name container1 --network my_network alpine sh and similarly for container2.

3

Ping container2 from container1 to test connectivity

Use docker exec to run the ping -c 3 container2 command inside container1 to check if it can reach container2.

Docker

docker network create my_network
docker run -dit --name container1 --network my_network alpine sh
docker run -dit --name container2 --network my_network alpine sh
# Your code here

Need a hint?

Run docker exec container1 ping -c 3 container2 to test connectivity.

4

Display the ping output

Run the command docker exec container1 ping -c 3 container2 and print its output to verify if the ping was successful.

Docker

docker network create my_network
docker run -dit --name container1 --network my_network alpine sh
docker run -dit --name container2 --network my_network alpine sh
docker exec container1 ping -c 3 container2
# Your code here

Need a hint?

The output should show lines starting with PING container2 and replies if successful.