[Docker] Rebuilding the Docker Image on change

I usually do my local development with docker containers and especially docker-compose. In the olden days, I would have to sync the changes manually, but now Docker has released Docker Compose Watch which lets you rebuild the application as soon as there are changes registered and rebuilds the docker container.

Let’s take for example a python application with app.py as the sole application running there. The Composefile would be as follow

services:
  test-app:
    build:
      context: .
    ports:
      - 8000:8000
    develop:
      watch:
        - action: sync
          path: .
          target: /app
        - action: rebuild
          path: ./app.py

After that, simply run docker compose watch. The Docker daemon will be watching your codes for a change and rebuild upon change.