SivaLabs

TLDR;

I am happy to announce that I am going to create “SpringBoot Tips Video Series” on my SivaLabs YouTube Channel. This “SpringBoot Tips Series” is to help people who are new to SpringBoot to learn how to use SpringBoot with a keen focus on understanding how it works behind the scenes.

If you know me you know that I am a big fan of Spring ecosystem. I have been using Spring framework since 2007, and I am pretty familiar with many of its features.

Even if we are familiar with some technology once in a while we get stuck with small issues and end up spending hours and hours figuring out why something is not working as expected.

One of the many reasons for huge popularity of Spring and SpringBoot is it’s great support for Testing. We can write unit tests using Mockito without requiring any Spring features. And, we can write Integration Tests using Spring testing support by creating Spring ApplicationContext.

I have been working with Spring and SpringBoot for many years and I needed to create lot of Spring(Boot) applications for various reasons like blog posts, sample apps, book sample code and for my personal learning as well. So, I needed some tool/mechanism to quickly create Spring(Boot) application with most commonly used configuration.

SpringBoot is the most popular tech stack for building Java based REST APIs. In this tutorial we will learn how to write tests for SpringBoot applications.

• Create SpringBoot Application
• Unit Testing using JUnit 5 and Mockito
• Integration Testing using TestContainers
• Testing MicroService Integrations using MockServer

I have been working with SpringBoot for many years and over the time I worked with many SpringBoot based codebases. There are few common mistakes that I observe in the projects that use SpringBoot. So, I thought of writing down few good practices that can be followed while using SpringBoot.

One of the challenges in microservices architecture is the ability to debug issues. A simple user action might trigger a chain of downstream microservice calls. It would be tedious to trace the logs related to a particular user action across microservices. In addition to that, we might want to track down why a certain microservice call is taking so much time. We can use Spring Cloud Sleuth to handle these kinds of issues.

In microservices architecture, there could be a number of API services and few UI components that are talking to APIs. As of now, many microservices based application still use monolithic front-ends where the entire UI is built as a single module. You may choose to go with micro-frontends where the UI is also decomposed into multiple microservice talking to APIs to get the relevant data. Instead of letting UI know about all our microservices details we can provide a unified proxy interface that will delegate the calls to various microservices based on URL pattern. In this post, we will learn how to create API Gateway using Spring Cloud Zuul Proxy.

In the microservices world, to fulfill a client request one microservice may need to talk to other microservices. We should minimize this kind of direct dependencies on other microservices but in some cases it is unavoidable. If a microservice is down or not functioning properly then the issue may cascade up to the upstream services. Netflix created Hystrix library implementing Circuit Breaker pattern to address these kinds of issues.

In the microservices world, Service Registry and Discovery plays an important role because we most likely run multiple instances of services and we need a mechanism to call other services without hardcoding their hostnames or port numbers. In addition to that, in Cloud environments service instances may come up and go down anytime. So we need some automatic service registration and discovery mechanism. Spring Cloud provides Service Registry and Discovery features, as usual, with multiple options. We can use Netflix Eureka or Consul for Service Registry and Discovery.