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Docker for Rails Developers

Compiling Assets with Webpacker

Explore how to integrate Webpacker with Docker to compile Rails JavaScript assets efficiently. Understand configuring webpack-dev-server as its own container service and adjusting Docker Compose for seamless live reloading during development.

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webpack-dev-server

As part of Webpacker, Rails provides the webpack-dev-server binary. This is a small server that runs in the background, automatically compiling our webpack-managed files.

If you were developing locally, this would just be another command you would issue from your terminal. However, the Docker way is to run this as a separate service in its own container.

Modification of Compose

Let’s add a new service for it to our docker-compose.yml file:

YAML
version: '3'
services:
  web:
      build: .
      ports:
           - "3000:3000"
      volumes:
           - .:/usr/src/app
      env_file:
           - .env/development/database
           - .env/development/web
      environment:
           - WEBPACKER_DEV_SERVER_HOST=webpack-dev-server
  webpack-dev-server:
      build: .
      command: ./bin/webpack-dev-server
      ports:
           - 3035:3035
      volumes:
           - .:/usr/src/app
      env_file:
           - .env/development/web
           - .env/development/database
      environment:
           - WEBPACKER_DEV_SERVER_HOST=0.0.0.0
  redis:
      image: redis
  database:
      image: postgres
      env_file:
           - .env/development/database
      volumes:
           - db_data:/var/lib/postgresql/data
volumes:
    db_data:

Explanation

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