Compose watch for development in Docker - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this Docker Compose watch command?

You run this command to watch file changes and restart the service automatically:

docker compose watch

What will you see in the terminal when a source code file changes?

A The container restarts but does not rebuild the image, showing only logs.

B The service ignores file changes and continues running without any output.

C The service rebuilds and restarts automatically, showing build logs and container logs.

D The command exits immediately with an error about missing watch flag.

💡 Hint

`docker compose watch` detects changes in the build context.

`docker compose watch` monitors the build context for changes, rebuilds the image if needed, recreates and restarts the container, showing build logs and container logs.

❓ Configuration

intermediate

Which docker-compose.yml snippet enables live code reload with volume mounting?

You want your container to reflect code changes immediately during development. Which volume configuration achieves this?

A

volumes:
  - ./app

B

volumes:
  - ./app:/app

C

volumes:
  - app:/app

D

volumes:
  - /app

💡 Hint

Mount your local folder into the container path.

Mounting ./app on the host to /app in the container syncs code changes immediately.

🔀 Workflow

advanced

What is the correct sequence to enable live reload with Docker Compose and nodemon?

You want to develop a Node.js app with live reload inside a container using nodemon. Which sequence of steps is correct?

A 1,2,3,4

B 2,1,3,4

C 1,3,2,4

D 3,1,2,4

💡 Hint

Think about installing tools before configuring and running.

First install nodemon, then mount code, set command to nodemon, then start container.

❓ Troubleshoot

advanced

Why does your container not reflect code changes despite volume mounting?

You mounted your local code folder into the container, but changes are not visible inside the container. What is the most likely cause?

A The container runs a built image that overwrites the mounted volume at startup

B The container has no network access

C Docker daemon is not running

D The volume path on the host is incorrect or empty

💡 Hint

Verify the host-side path first.

If the host path (e.g., ./app) is incorrect, doesn't exist, or is empty, the container won't see the expected files despite the volume mount.

✅ Best Practice

expert

Which approach best supports fast iterative development with Docker Compose?

You want to develop a Python web app with fast code reload and minimal container rebuilds. Which setup is best?

A Use volume mounts for source code, run the app with a file watcher like 'watchmedo', and rebuild images only when dependencies change

B Copy source code into image during build and restart container on every code change

C Run the app inside the container without volume mounts and rebuild image on every code change

D Use bind mounts only for dependencies folder and copy source code into image

💡 Hint

Minimize rebuilds and use live reload tools.

Mounting source code and using a watcher inside container avoids rebuilds and speeds development.