Microservices with Spring Boot and Spring Cloud

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Microservices with Java, Spring Boot & Spring Cloud Eberhard Wolff Fellow, innoQ @ewolff

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http://microservices-buch.de/ http://microservices-book.com/

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http://microservices-book.com/primer.html FREE!!!!

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Microservice Definition

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Server Server Microservices: Definition > Small > Independent deployment units > Any technology > Any infrastructure Micro Service Micro Service

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Components Collaborate Micro Service Micro Service Link Data Replication REST Messaging

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Infrastructure > …must support lots of services > Easy to create a new project > REST integrated > Messaging supported > Uniform operations

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Spring Boot Demo

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Simple Infrastructure > One pom.xml > …or Gradle / Ant > Very few dependencies > One plug in > Versions defined

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REST Integrated > Support in Spring MVC > As we have seen > Also: JAX-RS > Jersey

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Messaging Support > Numerous Spring Boot Starter > AMQP (RabbitMQ) > HornetQ (JMS) > ActiveMQ Artemis (JMS)

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Messaging Support > Spring JMS abstraction > Message driven POJOs > Scalable > Simplify sending JMS > Can use other libs, too! > Boot: everything Spring / Java can do

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Infrastructure > …must support lots of services > Easy to create a new project > REST integrated > Messaging supported > Simple deployment > Uniform operations ✓ ✓ ✓

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Deploy > Package everything in an executable JAR > …or a WAR > Based on Maven, Ant or Gradle > Add configuration

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Spring Boot Deploy Demo

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Deploy > Install a basic machine > Install Java > Copy over JAR > Optional: Make it a Linux Service > …just a link > Optional: Create application.properties

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Infrastructure > …must support lots of services > Easy to create a new project > REST integrated > Messaging supported > Simple deployment > Uniform operations ✓ ✓ ✓ ✓

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Spring Boot Actuator > Provide information about the application > Via HTTP / JSON > …or Metrics > Can be evaluated by monitoring tools etc. > E.g. Graphite, Grafana ….

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Spring Boot Actuator Demo

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> https://github.com/ewolff/user-registration-V2 > Logging ELK > Subdir log-analysis > Monitoring Graphite > Subdir graphite

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Infrastructure > …must support lots of services > Easy to create a new project > REST integrated > Messaging supported > Simple deployment > Uniform operations ✓ ✓ ✓ ✓ ✓

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Spring Cloud

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Based on Spring Boot

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Supports many technology stacks, Clouds, …

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Focus: Netflix Stack

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Spring Cloud Netflix Zuul Routing Ribbon Client Side Load Balancing Eureka Service Discovery Hystrix Resilience

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Coordinating Microservices

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> Must find each other Microservice Microservice

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Service Discovery Eureka

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Why Eureka? > REST based service registry > Supports replication > Caches on the client > Resilient > Fast > …but not consistent > Foundation for other services

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Eureka Client in Spring Cloud > @EnableDiscoveryClient: generic > @EnableEurekaClient: more specific > Dependency to spring-cloud-starter-eureka > Automatically registers application

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application.properties eureka.client.serviceUrl.defaultZone=http://host:8761/eureka/ eureka.instance.leaseRenewalIntervalInSeconds=5 spring.application.name=catalog eureka.instance.metadataMap.instanceId=${spring.application.name}:${r andom.value} eureka.instance.preferIpAddress=true Eureka server Can include user / password Need unique ID Load balancing Faster updates Dockerwon’t resolve host names Used for registration In CAPITAL caps

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Eureka Server @EnableEurekaServer @EnableAutoConfiguration public class EurekaApplication { public static void main(String[] args) { SpringApplication.run(EurekaApplication.class, args); } } Add dependency to spring-cloud-starter-eureka-server

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> Must find each other > Route calls to a service Microservice Microservice

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Zuul Routing

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Routing > One URL to the outside > Internal: Many Microservices > In particular: REST > Power through filters

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Customer Order Catalog Zuul Proxy Automatically maps route to server registered on Eureka i.e. /customer/** to CUSTOMER No configuration Can add filters etc

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Zuul Proxy @SpringBootApplication @EnableZuulProxy public class ZuulApplication { public static void main(String[] args) { new SpringApplicationBuilder(ZuulApplication.class). web(true).run(args); } } Enable Zuul Proxy Can change route Also routing to external services possible

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> Must find each other > Route calls to a service > Configuration Microservice Microservice

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Spring Cloud Config

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Configuration > Spring Cloud Config > Central configuration > Dynamic updates > Can use git backend > I prefer immutable server > & DevOps tools (Docker, Chef…)

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Spring Cloud Bus > Pushed config updates > …or individual message > I prefer a messaging solution > Independent from Spring

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> Must find each other > Route calls to a service > Configuration > Security Microservice Microservice

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Spring Cloud Security

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Spring Cloud Security > Single Sign On via OAuth2 > Forward token e.g. via RestTemplate > Support for Zuul > Very valuable!

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Implementing Microservices

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Microservice Microservice > Load Balancing

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Load Balancing Ribbon

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Proxy Load Balancing > Centralized Load Balancing > Can become bottle neck > Single point of failure > Configuration complex Load Balancer Server Client

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Client Ribbon: Client Side Load Balancing > Decentralized Load Balancing > No bottle neck > Resilient > Can consider response time > Data might be inconsistent Load Balancer Server

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RestTemplate & Load Balancing @RibbonClient(name = "ribbonApp") … public class RibbonApp { @Autowired private RestTemplate restTemplate; public void callMicroService() { Store store = restTemplate. getForObject("http://stores/store/1", Store.class); } Enable Ribbon Left out other annotations Eureka name or server list Standard Spring REST client Can also use Ribbon API

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Microservice Microservice > Load Balancing > Resilience

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Hystrix Resilience

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Hystrix > Enable resilient applications > Do call in other thread pool > Won’t block request handler > Can implement timeout

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Hystrix > Circuit Breaker > If call system fail open > If open do not forward call > Forward calls after a time window > System won’t be swamped with requests

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Hystrix / Spring Cloud > Annotation based approach > Annotations of javanica libraries > Java Proxies automatically created > Simplifies Hystrix dramatically > No commands etc

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@HystrixCommand(fallbackMethod = "getItemsCache") public Collection findAll() { … this.itemsCache = pagedResources.getContent(); return itemsCache; } private Collection getItemsCache() { return itemsCache; } Fallback

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Stream via http Circuit Breaker status Thread Pool status

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Conclusion

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Infrastructure > Easy to create a new project > REST integrated > Messaging supported > Simple deployment > Uniform operations

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Spring Cloud > Eureka: Service Discovery > Zuul: Route calls to a service > Spring Cloud Config: Configuration > Ribbon: Load Balancing > Hystrix: Resilience

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Links > https://github.com/ewolff/microservices > https://github.com/ewolff/spring-boot-demos > https://github.com/ewolff/user-registration-V2 > http://projects.spring.io/spring-boot/ > http://projects.spring.io/spring-cloud > https://spring.io/guides/ > http://microservices-book.com

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Thank You!! @ewolff