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.

✅ 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.

⚙️ 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

📄 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

🔍 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

🤝 Why Use `networks:`?

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

✅ 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.

🎯 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

🧠 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.

SOVANNARO @sovannaro