如何配置Docker使init.js仅运行一次、app.js每次执行docker compose up时均运行？

Absolutely, there's a straightforward, reliable way to make this work with Docker Compose! Let's break down the setup so other users can pull your repo and run docker compose up without worrying about init.js running every time.

Core Approach #

We'll split your stack into three dedicated services in docker-compose.yml:

1. A MongoDB service with persistent storage (so your seeded data stays intact across restarts).
2. A one-off initialization service that runs init.js exactly once (only after MongoDB is fully ready).
3. Your main app service that runs app.js every time you start the stack.

Step 1: Keep Your Existing Dockerfile #

No changes needed here! Your current Dockerfile already includes all dependencies, init.js, and app.js—it works perfectly for both the initialization and app services.

Step 2: Create/Update Your docker-compose.yml #

Add this complete configuration to your project root:

version: '3.8'

services:
  # MongoDB service with persistent data storage
  mongo:
    image: mongo:latest
    volumes:
      - mongodb_data:/data/db  # Persists DB data between container restarts
    ports:
      - "27017:27017"

  # One-time DB seeding service
  init-mongo:
    build: ./backend  # Reuses your Node.js Dockerfile
    depends_on:
      - mongo
    restart: "no"  # Critical: prevents this service from re-running after completion
    # Wait for MongoDB to be fully operational before running init.js
    command: >
      sh -c "
        until mongosh --host mongo --eval 'db.runCommand({ ping: 1 })'; do
          echo 'Waiting for MongoDB to be ready...';
          sleep 2;
        done;
        echo 'MongoDB is ready! Seeding database...';
        node init.js;
      "

  # Main app service (runs every time)
  app:
    build: ./backend
    depends_on:
      - mongo
      - init-mongo  # Ensures app starts only after DB seeding finishes
    restart: "always"  # Guarantees the app runs on every docker compose up
    ports:
      - "3000:3000"  # Adjust to match your app's listening port
    environment:
      - MONGO_URI=mongodb://mongo:27017/your-database-name  # Update to your actual DB name

# Persistent volume for MongoDB data
volumes:
  mongodb_data:

What Happens for Other Users #

When someone pulls your repo and runs docker compose up:

1. The mongo service starts and creates a persistent volume to store database data.
2. The init-mongo service builds your Node image, waits for MongoDB to be fully ready (not just the container running), then executes init.js to seed the database. Once done, the container exits and won't restart.
3. The app service launches only after init-mongo completes, running app.js via your npm start command. Every subsequent docker compose up will skip the init-mongo service (since its container already ran successfully) and start the app immediately.

Resetting the Initialization (If Needed) #

If you or a user ever needs to re-run init.js (e.g., to reset the database), just delete the MongoDB volume and restart the stack:

docker compose down -v
docker compose up

内容的提问来源于stack exchange，提问作者Jushraf Rahi