Microservices with Java, Spring Boot and Spring Cloud
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Spring Boot makes creating small Java application easy - and also facilitates operations and deployment. But for Microservices need more: Because Microservices are a distributed systems issues like Service Discovery or Load Balancing must be solved. Spring Cloud adds those capabilities to Spring Boot using e.g. the Netflix stack. This talks covers Spring Boot and Spring Cloud and shows how these technologies can be used to create a complete Microservices environment.
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Microservices with Java, Spring Boot and Spring Cloud
- 1. Microservices with Java, Spring Boot & Spring Cloud Eberhard Wolff Fellow, innoQ @ewolff
- 6. Server Server Microservices: Definition > Small > Independent deployment units > Any technology > Any infrastructure Micro Service Micro Service
- 8. Infrastructure > …must support lots of services > Easy to create a new project > REST integrated > Messaging supported > Uniform operations
- 10. Simple Infrastructure > One pom.xml > …or Gradle / Ant > Very few dependencies > One plug in > Versions defined
- 11. REST Integrated > Support in Spring MVC > As we have seen > Also: JAX-RS > Jersey
- 12. Messaging Support > Numerous Spring Boot Starter > AMQP (RabbitMQ) > HornetQ (JMS) > ActiveMQ Artemis (JMS)
- 13. Messaging Support > Spring JMS abstraction > Message driven POJOs > Scalable > Simplify sending JMS > Can use other libs, too! > Boot: everything Spring / Java can do
- 14. Infrastructure > …must support lots of services > Easy to create a new project > REST integrated > Messaging supported > Simple deployment > Uniform operations ✓ ✓ ✓
- 15. Deploy > Package everything in an executable JAR > …or a WAR > Based on Maven, Ant or Gradle > Add configuration
- 17. Deploy > Install a basic machine > Install Java > Copy over JAR > Optional: Make it a Linux Service > …just a link > Optional: Create application.properties
- 18. Infrastructure > …must support lots of services > Easy to create a new project > REST integrated > Messaging supported > Simple deployment > Uniform operations ✓ ✓ ✓ ✓
- 19. Spring Boot Actuator > Provide information about the application > Via HTTP / JSON > …or Metrics > Can be evaluated by monitoring tools etc. > E.g. Graphite, Grafana ….
- 21. > https://github.com/ewolff/user-registration-V2 > Logging ELK > Subdir log-analysis > Monitoring Graphite > Subdir graphite
- 22. Infrastructure > …must support lots of services > Easy to create a new project > REST integrated > Messaging supported > Simple deployment > Uniform operations ✓ ✓ ✓ ✓ ✓
- 23. Spring Cloud
- 24. Based on Spring Boot
- 27. Spring Cloud Netflix Zuul Routing Ribbon Client Side Load Balancing Eureka Service Discovery Hystrix Resilience
- 29. > Must find each other Microservice Microservice
- 31. Why Eureka? > REST based service registry > Supports replication > Caches on the client > Resilient > Fast > …but not consistent > Foundation for other services
- 32. Eureka Client in Spring Cloud > @EnableDiscoveryClient: generic > @EnableEurekaClient: more specific > Dependency to spring-cloud-starter-eureka > Automatically registers application
- 33. 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 Needunique ID Load balancing Faster updates Dockerwon’t resolve host names Used for registration In CAPITAL caps
- 34. 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
- 36. > Must find each other > Route calls to a service Microservice Microservice
- 37. Zuul Routing
- 38. Routing > One URL to the outside > Internal: Many Microservices > In particular: REST > Power through filters
- 39. Customer Order Catalog Zuul Proxy Automatically maps route to server registered on Eureka i.e. /customer/** to CUSTOMER No configuration Can add filters etc
- 40. 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
- 41. > Must find each other > Route calls to a service > Configuration Microservice Microservice
- 43. Configuration > Spring Cloud Config > Central configuration > Dynamic updates > Can use git backend > I prefer immutable server > & DevOps tools (Docker, Chef…)
- 44. Spring Cloud Bus > Pushed config updates > …or individual message > I prefer a messaging solution > Independent from Spring
- 45. > Must find each other > Route calls to a service > Configuration > Security Microservice Microservice
- 47. Spring Cloud Security > Single Sign On via OAuth2 > Forward token e.g. via RestTemplate > Support for Zuul > Very valuable!
- 49. Microservice Microservice > Load Balancing
- 51. Proxy Load Balancing > Centralized Load Balancing > Can become bottle neck > Single point of failure > Configuration complex Load Balancer Server Client
- 52. Client Ribbon: Client Side Load Balancing > Decentralized Load Balancing > No bottle neck > Resilient > Can consider response time > Data might be inconsistent Load Balancer Server
- 53. 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
- 54. Microservice Microservice > Load Balancing > Resilience
- 56. Hystrix > Enable resilient applications > Do call in other thread pool > Won’t block request handler > Can implement timeout
- 57. 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
- 58. Hystrix / Spring Cloud > Annotation based approach > Annotations of javanica libraries > Java Proxies automatically created > Simplifies Hystrix dramatically > No commands etc
- 59. @HystrixCommand(fallbackMethod = "getItemsCache") public Collection<Item> findAll() { … this.itemsCache = pagedResources.getContent(); return itemsCache; } private Collection<Item> getItemsCache() { return itemsCache; } Fallback
- 60. Stream via http Circuit Breaker status Thread Pool status
- 61. Conclusion
- 62. Infrastructure > Easy to create a new project > REST integrated > Messaging supported > Simple deployment > Uniform operations
- 63. Spring Cloud > Eureka: Service Discovery > Zuul: Route calls to a service > Spring Cloud Config: Configuration > Ribbon: Load Balancing > Hystrix: Resilience
- 64. 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