Setting up docker-compose.yml to run all services

4.1 Initialization

In this step, we'll set up the compose.yaml file to start all the services of our multi-container application. The compose.yaml file will include configurations for the frontend, backend, and database, as well as the definition of networks and volumes.

Defining the Docker Compose version

Let's begin by specifying the Docker Compose version. In this example, version 3 is used:

version: '3'

4.2 Defining Services

Service 1: Frontend (ReactJS)

Let’s define a service for the frontend, which will be built from the frontend directory and will be available on port 3000:

services:
  frontend:
    build: ./frontend
    ports:
      - "3000:3000"
    networks:
      - task-network

Service 2: Backend (Flask)

Let’s define a service for the backend, which will be built from the backend directory. It depends on the database service and will be available on port 5000:

  backend:
    build: ./backend
    ports:
      - "5000:5000"
    depends_on:
      - database
    networks:
      - task-network
    environment:
      - DATABASE_URL=postgresql://taskuser:taskpassword@database:5432/taskdb

Where:

• depends_on: points out that the backend service depends on the database service. This means the database will start up before the backend.
• environment: configures environment variables to connect to the database.

Service 3: Database (PostgreSQL)

Let’s define a service for the database by using the official postgres:13 image. We’ll set up environment variables to create a database and user credentials:

  database:
    image: postgres:13
    environment:
      - POSTGRES_DB=taskdb
      - POSTGRES_USER=taskuser
      - POSTGRES_PASSWORD=taskpassword
    networks:
      - task-network
    volumes:
      - db-data:/var/lib/postgresql/data

Where:

• environment: configures environment variables to create the database and user when the container starts.
• volumes: attaches the db-data volume for persistent data storage.

4.3 Setting up networks and volumes

Let's define the networks and volumes that will be used by our services:

networks:
  task-network:
    driver: bridge
      
volumes:
  db-data:

Where:

• networks: defines the network task-network with a driver type bridge, which will be used for communication between containers.
• volumes: defines the volume db-data for storing the database data.

4.4 Complete docker-compose.yml File

Now let's combine all the parts into one docker-compose.yml file:

version: '3'

services:
  frontend:
    build: ./frontend
    ports:
      - "3000:3000"
    networks:
      - task-network
        
  backend:
    build: ./backend
    ports:
      - "5000:5000"
    depends_on:
      - database
    networks:
      - task-network
    environment:
      - DATABASE_URL=postgresql://taskuser:taskpassword@database:5432/taskdb
        
  database:
    image: postgres:13
    environment:
      - POSTGRES_DB=taskdb
      - POSTGRES_USER=taskuser
      - POSTGRES_PASSWORD=taskpassword
    networks:
      - task-network
    volumes:
      - db-data:/var/lib/postgresql/data
        
networks:
  task-network:
    driver: bridge
        
volumes:
  db-data:

Explanation of the Settings

• build: specifies the path to the directory with the Dockerfile to build the image.
• ports: opens ports on the host for accessing services.
• depends_on: indicates that a service depends on another to ensure startup order.
• environment: configures environment variables for services.
• networks: defines the network for communication between containers.
• volumes: defines volumes for persistent data storage.

4.5 Running the Application

Now that the compose.yaml file is set up, we can start all the services with one command:

docker compose up

This command will create and launch containers for the frontend, backend, and database, using the settings defined in compose.yaml.

Checking the launch

After starting the containers, make sure all the services are working correctly:

1. Frontend: open a browser and go to http://localhost:3000 to check the frontend.
2. Backend: open a browser and go to http://localhost:5000 to check the backend.
3. Database: make sure the database container is running and accessible through network interaction with the backend.

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Docker SELF, level 23, lesson 3

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Setting up a PostgreSQL Database

Setting up a PostgreSQL Database

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Docker SELF, level 23, lesson 3

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Full setup and launch of all services

Full setup and launch of all services

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