Spring Cloud aims to provide solutions to some of the commonly encountered patterns when building systems on the Cloud:

• Configuration management: As we discussed in the What is the Twelve-Factor App section, managing configuration is an important part of developing cloud-native applications. Spring Cloud provides a centralized configuration management solution for microservices—Spring Cloud Config.
• Service discovery: Service discovery promotes loose coupling between services. Spring Cloud provides integration with popular service discovery options, such as Eureka, ZooKeeper, and Consul.
• Circuit breakers: Cloud-native applications must be fault-tolerant. They should be able to handle the failure of backing services gracefully. Circuit breakers play a key role in providing the default minimum service in case of failures. Spring Cloud provides integration with the Netflix Hystrix fault tolerance library.
• API Gateway: An API Gateway provides centralized aggregation, routing, and caching services. Spring Cloud provides integration with the API Gateway library, Netflix Zuul.

It is important to understand that Spring Cloud is not a single project. It is a group of subprojects aimed at solving the problems associated with applications that are deployed on the Cloud.

Some important Spring Cloud subprojects are as follows:

• Spring Cloud Netflix: Netflix is one of the early adopters of the microservice architecture. A number of internal Netflix projects were open sourced under the umbrella of Spring Cloud Netflix. Examples include Eureka, Hystrix, and Zuul.
• Spring Cloud Config: Enables centralized external configuration across different microservices across different environments.
• Spring Cloud Bus: Makes it easier to build the integration of microservices with a lightweight message broker.
• Spring Cloud Sleuth: Along with Zipkin, this provides distributed tracing solutions.
• Spring Cloud Data Flow: Provides capabilities for building orchestration around microservice applications. Provides a DSL, GUI, and REST API.
• Spring Cloud Stream: Provides a simple declarative framework to integrate Spring-based (and Spring Boot-based) applications with message brokers such as Apache Kafka or RabbitMQ.

A few things are common to all projects under the Spring Cloud umbrella:

• They solve some of the common problems with developing applications on the Cloud.
• They provide great integration with Spring Boot.
• They are typically configured with simple annotations.
• They make extensive use of auto-configuration.

Let's start exploring some of the Spring Cloud projects in depth.