Week 03 - Multi-Service Application with Docker Compose

Overview

In Week 03, you will extend the University Course Registration System by introducing a microservices architecture and deploying multiple services using Docker Compose.

Unlike Week 02, which contained a single FastAPI application, this week's solution consists of:

• Student Service (FastAPI)
• Course Service (FastAPI)
• Student Database (PostgreSQL)
• Course Database (PostgreSQL)
• Frontend (React)

Docker Compose will be used to build, configure, network, and run all services using a single command.

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Learning Outcomes

After completing this practical, you should be able to:

• Understand a basic microservices architecture.
• Build and deploy multiple containers using Docker Compose.
• Connect multiple FastAPI services with PostgreSQL databases.
• Configure communication between containers.
• Execute unit tests for backend and frontend applications.
• Verify communication between frontend and backend services.

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Application Architecture

                    Browser
                        |
                  React Frontend
                        |
        ---------------------------------
        |                               |
 Student Service                 Course Service
        |                               |
 PostgreSQL (students)          PostgreSQL (courses)

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Prerequisites

Before starting this practical, ensure you have the following installed.

Node.js (Required for React Frontend)

Download:

https://nodejs.org/

Verify installation:

node --version
npm --version

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Project Structure

week03/
│
├── student-service/
├── course-service/
├── frontend/
├── docker-compose.yml
├── README.md
└── .gitignore

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Setup Instructions

1. Clone the Repository

git clone https://github.com/sit722-devops/week03.git

2. Navigate to the Project

cd week03

3. Open the Project

Open the week03 folder using Visual Studio Code.

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Backend Setup

The Student Service and Course Service each have their own Python environment and dependencies.

Student Service

Navigate to the Student Service.

cd student-service

Create a virtual environment.

# Create the virtual environment
python -m venv .venv

# Activate the virtual environment
# On macOS/Linux:
source ./.venv/bin/activate
# On Windows (Command Prompt):
# .\.venv\Scripts\activate.bat
# On Windows (PowerShell):
# .\.venv\Scripts\Activate.ps1

Install dependencies.

pip install -r requirements.txt

Return to the project root.

cd ..

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Course Service

Navigate to the Course Service.

cd course-service

Create a virtual environment.

# Create the virtual environment
python -m venv .venv

# Activate the virtual environment
# On macOS/Linux:
source ./.venv/bin/activate
# On Windows (Command Prompt):
# .\.venv\Scripts\activate.bat
# On Windows (PowerShell):
# .\.venv\Scripts\Activate.ps1

Install dependencies.

pip install -r requirements.txt

Return to the project root.

cd ..

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Frontend Setup

Navigate to the frontend.

cd frontend

Install the required Node.js packages.

npm install

Return to the project root.

cd ..

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Execute Unit Tests

Before deploying the application using Docker Compose, ensure all unit tests pass successfully.

Student Service

cd student-service
pytest tests
cd ..

NOTE: The Student Service unit tests require a PostgreSQL database named students. If the database does not already exist, create it before running the tests. CREATE DATABASE students; The test suite will automatically create the required database tables if they do not already exist.

Course Service

cd course-service
pytest tests
cd ..

NOTE: The Course Service unit tests require a PostgreSQL database named courses. If the database does not already exist, create it before running the tests. CREATE DATABASE courses; The test suite will automatically create the required database tables if they do not already exist.

Frontend

cd frontend
npm test
cd ..

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Run the Application Using Docker Compose

From the project root directory, execute:

docker compose build --no-cache

docker compose build -d

Docker Compose will automatically:

• Build the Student Service image.
• Build the Course Service image.
• Build the Frontend image.
• Create the Student PostgreSQL database container.
• Create the Course PostgreSQL database container.
• Create the Docker network.
• Connect all services together.

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Verify Running Containers

Run following:

docker compose ps

You should see the following containers running:

• frontend
• student-service
• course-service
• student-db
• course-db

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View Container Logs

View logs for all containers.

docker compose logs

View logs for the Student Service.

docker compose logs student-service

View logs for the Course Service.

docker compose logs course-service

View logs for the Frontend.

docker compose logs frontend

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Access the Application

Frontend

http://localhost:5173

Student Service Swagger UI

http://localhost:8001/docs

Course Service Swagger UI

http://localhost:8002/docs

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Verify the Application

Using the frontend:

• Create a new student.
• Verify the student appears in the Students table.
• Create a new course.
• Verify the course appears in the Courses table.

Using Swagger UI:

Student Service

• GET /students
• GET /students/{student_id}
• POST /students

Course Service

• GET /courses
• GET /courses/{course_id}
• POST /courses

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Stop the Application

Stop all running containers.

docker compose down

To also remove the PostgreSQL volumes and start with a fresh database next time, run:

docker compose down -v