Build a Tiny Spring Boot Profile Microservice

How to Develop a Minimal Spring Boot Microservice for Your Backend

Developing microservices with Spring Boot can streamline your backend tasks significantly. In this post, I'll guide you through creating a simple Spring Boot service for a backend task. This service not only returns a user profile but also delivers a unique cat fact. Let's explore the architecture and implementation.

What Does This Microservice Do?

This microservice offers a straightforward GET endpoint at /me. When accessed, it delivers a JSON payload containing:

• Status: Shows the request's success status.
• User Profile: Details the user's name, role, and links.
• Timestamp: Marks the request time.
• Cat Fact: A fun fact from an external API, found at https://catfact.ninja/fact.

What's the Architecture Like?

The microservice's architecture emphasizes simplicity. Here's a breakdown:

ProfileController

The ProfileController manages requests to the /me endpoint, returning a ProfileResponse DTO with the requested data.

ProfileService

The ProfileService constructs the user profile and retrieves the cat fact using Java's HttpClient. This design simplifies testing by isolating external API calls.

Profile and ProfileResponse

Both Profile and ProfileResponse are straightforward POJOs that outline the returned data's structure. This approach keeps the codebase clean and organized.

Spring Boot Entrypoint

A standard Spring Boot entrypoint facilitates running the application, complemented by a basic unit test to verify application context loading.

Why Opt for This Design?

This microservice's design is intentional, aiming to:

• Minimize Complexity: Enables quick review of the domain, controller, and service.
• Isolate External Calls: Locates external API calls in the service for easier testing.
• Keep the Codebase Compact: A smaller codebase is preferable for early-stage tasks, focusing feedback.

Running the Microservice Locally

To run this microservice on your local machine, follow these steps:

1. Go to the project's root directory.
2. Start the application using the Maven wrapper:

   ./mvnw spring-boot:run
   

3. Visit http://localhost:8080/me in your browser.

Lessons Learned and Future Directions

This project offered several insights:

• Embrace Small Services: Small, focused services streamline review processes.
• Inject HttpClient: Future projects will benefit from injecting HttpClient or a wrapper for testability.
• Improve Error Handling and Logging: Structured error handling and logging will bolster application robustness.
• Expand Testing: My next steps include mocking the cat fact API in unit tests and adding an integration test for the controller.

Conclusion

Creating a small Spring Boot microservice goes beyond just setting up an endpoint. It's about designing an application that's straightforward and maintainable. By prioritizing simplicity, I've prepared a solid foundation for further learning and development in backend engineering. For those interested in diving into the code, you can find the repository here.