3 Microservices, 1 YAML File, 1 Command: The Power of Docker Compose

🛠️ Problem: Too Many docker run Commands

Right now, you have Docker images for three microservices:

• accounts
• loans
• cards

To run each one, you’d normally do:

docker run -p <port>:<port> <image-name>

But imagine doing that for 100 microservices or even just multiple instances.
💡 Manually running each with docker run becomes slow and painful.

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✅ Solution: Use Docker Compose

What is Docker Compose?

Docker Compose is a tool that lets you:

• Define all microservices in one YAML file.
• Start or stop all services with just one command.

👉 Instead of typing docker run multiple times, you write everything once in a file called docker-compose.yml.

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⚙️ What Can Docker Compose Do?

• Start all microservices with docker compose up
• Stop everything with docker compose down
• Set memory limits
• Link services together with a shared network
• View logs, restart services, and more

Docker Compose is installed automatically with Docker Desktop

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📄 Let's Create a docker-compose.yml

Put the file anywhere you want (e.g., in your accounts project folder).

Step-by-step Structure:

services:
  accounts:
    image: "your-username/accounts:s4"
    container_name: accounts-ms
    ports:
      - "8080:8080"
    deploy:
      resources:
        limits:
          memory: 700m
    networks:
      - easybank

  loans:
    image: "your-username/loans:s4"
    container_name: loans-ms
    ports:
      - "8090:8090"
    deploy:
      resources:
        limits:
          memory: 700m
    networks:
      - easybank

  cards:
    image: "your-username/cards:s4"
    container_name: cards-ms
    ports:
      - "9000:9000"
    deploy:
      resources:
        limits:
          memory: 700m
    networks:
      - easybank

networks:
  easybank:
    driver: bridge

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🔍 Explanation:

Key	Meaning
services:	Section where you define each microservice
image:	The Docker image to use (add your Docker Hub username)
container_name:	Give your container a readable name
ports:	Map internal ports to your machine
deploy > resources > limits:	Restrict memory usage
networks:	Allow microservices to talk to each other
easybank (at bottom):	Creates a shared network all services use

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🤝 Why Use networks:?

Without a shared network, microservices can’t talk to each other.
Adding them to the same network (like easybank) enables communication.

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✅ Final Steps

To check if Docker Compose is installed:

docker compose version

If not, visit the Docker Compose install page and follow the steps for your OS.

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🎯 What’s Next?

Now that your docker-compose.yml is ready, you can:

Start all services with:

docker compose up

Stop all services with:

docker compose down

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🧠 Summary

• docker-compose.yml lets you manage all services in one file.
• You define images, ports, memory limits, and networks.
• Use docker compose up to launch everything with one command.
• It saves time and avoids manual repetition.