Sharing volumes between containers in Docker - Mini Project: Build & Apply

Sharing volumes between containers

📖 Scenario: You are working on a project where two Docker containers need to share files. One container will create a file, and the other container will read it. This is common when containers need to exchange data without using a network.

🎯 Goal: Build two Docker containers that share a volume. The first container writes a file to the shared volume. The second container reads and displays the file content from the same volume.

📋 What You'll Learn

Create a Docker volume named shared_data

Run a container named writer that writes a file /data/message.txt with the text Hello from writer container!

Run a container named reader that reads and prints the content of /data/message.txt

Both containers must use the shared_data volume mounted at /data

💡 Why This Matters

🌍 Real World

Sharing volumes between containers is common when multiple services need access to the same files, such as logs, configuration, or data files.

💼 Career

Understanding Docker volumes is essential for DevOps roles to manage persistent data and enable communication between containers in real projects.

1

Create a Docker volume named shared_data

Write the Docker command to create a volume called shared_data.

Docker

# Your code here

Need a hint?

Use docker volume create followed by the volume name.

2

Run a container named writer that writes a file to the volume

Write the Docker command to run a container named writer that mounts the shared_data volume at /data and writes the text Hello from writer container! into the file /data/message.txt. Use the alpine image and the command sh -c "echo 'Hello from writer container!' > /data/message.txt".

Docker

docker volume create shared_data
# Your code here

Need a hint?

Use docker run --rm --name writer -v shared_data:/data alpine sh -c "echo 'Hello from writer container!' > /data/message.txt".

3

Run a container named reader that reads the file from the volume

Write the Docker command to run a container named reader that mounts the shared_data volume at /data and reads the content of /data/message.txt using cat. Use the alpine image and the command cat /data/message.txt.

Docker

docker volume create shared_data
docker run --rm --name writer -v shared_data:/data alpine sh -c "echo 'Hello from writer container!' > /data/message.txt"
# Your code here

Need a hint?

Use docker run --rm --name reader -v shared_data:/data alpine cat /data/message.txt.

4

Display the content of the shared file from the reader container

Run the full set of commands to create the volume, write the file, and then read and print the file content. The output should be exactly Hello from writer container!.

Docker

docker volume create shared_data
docker run --rm --name writer -v shared_data:/data alpine sh -c "echo 'Hello from writer container!' > /data/message.txt"
docker run --rm --name reader -v shared_data:/data alpine cat /data/message.txt
# Run the commands and observe the output

Need a hint?

Run all commands in order. The last command prints the message.