Spring Cloud Microservices is the answer to building Spring Boot Microservices for the cloud.
Basically, Spring Cloud is a microservices framework. It provides tools for developers to build some of the most common patterns associated with distributed systems. These common patterns are configuration management, service discovery, circuit breaker, API gateway and so on.
A lot of the effort around implementing these patterns is pretty common across different installations. Therefore, it could also be seen as boilerplate code.
Spring Cloud projects make it easy for developers to build Spring Cloud Microservices using these patterns. These services will work well in any deployment environment. Whether it is the developers laptop, a bare metal server, or a cloud platform such as AWS or Openshift.
Spring Cloud Projects
The overall Spring Cloud framework is structured around the concept of projects. Each project within the larger family implements a certain pattern.
Based on the functionality, a developer can decide which project to include while building Spring Cloud Microservices.
All Spring Cloud applications are also built using Spring Boot as the base. Spring Boot acts as the foundation for building Spring Cloud Microservices. The main difference between them is that Spring Cloud helps typical Spring Boot applications work in an overall microservices architecture.
We will look at the main patterns supported under Spring Cloud.
Configuration Management with Spring Cloud
One of the important aspects of microservices is to externalize the configuration. It is better to have distributed configuration management. This makes all microservices adhere to a common configuration setup.
Spring Cloud Config Server allows developers to create a central config server. The config server reads the configuration file from any version control tool such as Git. Other applications can simply connect to this config server to receive their configuration items. In fact, developers can also update configuration settings without the need to restart the application.
Apart from Config Server, Spring Cloud also provides support for Consul. Spring Cloud Consul project allows Spring Boot applications to connect to a Consul agent that can manage the configuration.
Service Registration and Service Discovery with Spring Cloud
A typical microservice-based application can have many services and their corresponding instances. Individual services can scale up or down depending on different factors. All of this happens in a dynamic manner.
Therefore, we need Service Registration and Service Discovery mechanisms. This is to ensure that service communication does not happen by way of hard-coded hostnames or port numbers.
Spring Cloud Netflix Eureka is a project under Spring Cloud that allows self-registration of services as well as service discovery.
Also, as a latest addition, Spring Cloud Consul has also been integrated. It is an equally robust option for both service registration and discovery of Spring Cloud Microservices.
API Gateway Pattern with Spring Cloud
API Gateways are a necessity in a microservice-based application. Gateways provide a single entry point to your services. Also, such gateways can also handle common concerns such as authentication and authorization.
Spring Cloud Netflix Zuul lets us build such a gateway by simply using a Spring Boot application.
Circuit Breaker Pattern with Spring Cloud
In microservices architecture, one service may depend on another service. And if one service goes down, it might result in cascading failures across multiple services. This is largely an undesirable situation for high-availability systems.
Spring Cloud Hystrix allows the developers to easily implement Circuit Breaker pattern. In other words, using this project, you can build Spring Cloud Microservices that react appropriately to failures and also regain the normal flow once it is available.
Tracing Logs in Spring Cloud Microservices
In a microservices architecture, logs play an extremely important role in case of any production issues. However, most of the times, it is not easy to pin-point the exact logs and correlate a sequence of logs into a particular request.
However, Spring Cloud Sleuth makes it very easy to identify logs related to a specific request. It adds unique identifiers to every request and the associated steps, thereby making it easy to figure out which log entry belongs to which request.
Microservice Communication using Spring Cloud
Many times, microservices need to talk to each other. And many times, the communication approach is event-driven. Spring Cloud helps achieve such a communication style using Spring Cloud Stream.
Basically, Spring Cloud Stream makes it easy to exchange messages between two applications. Using Spring Cloud Stream, we can abstract away the details of message broker. The message broker can be RabbitMQ or Kafka or any other option.
In microservices communication using Spring Cloud Stream and RabbitMQ, we understand what is Spring Cloud Stream. We also look at steps to exchange messages between two microservices using RabbitMQ.
Conclusion
Spring Cloud is a great extension to Spring Boot and Spring framework in general. It enhances developer productivity and allows them to build cloud-ready microservices in no time.
It largely helps developers get rid of boilerplate code. At the same time, it provides support for important patterns that are a must to build Spring Cloud Microservices.
Have you used Spring Cloud?
If not, then what other frameworks do you use?
Do share your experiences in the comments section below.
Happy Learning!
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