Spring Cloud, Spring Boot and Netflix OSS

Spencer Gibb, Dave Syer, 2015

Authors

Spencer Gibb,
@spencerbgibb,
sgibb@pivotal.io

Dave Syer,
@david_syer,
dsyer@pivotal.io

Links

Outline

Define microservices
Outline some distributed system problems
Introduce Netflix OSS and its integration with Spring Boot
Spring Cloud demos

What are microservices?

Not monolithic :-)
Smaller units of a larger system
Runs in its own process
Lightweight communication protocols
Single Responsibility Principle
The UNIX way

http://www.slideshare.net/ewolff/micro-services-small-is-beautiful
http://martinfowler.com/articles/microservices.html
http://davidmorgantini.blogspot.com/2013/08/micro-services-what-are-micro-services.html

Spring Boot

It needs to be super easy to implement and update a service:

@RestController
class ThisWillActuallyRun {
    @RequestMapping("/")
    String home() {
        Hello World!
    }
}

and you don’t get much more "micro" than that.

Cloud Foundry

Deploying services needs to be simple and reproducible

$ cf push app -p app.groovy

and you don’t get much more convenient than that.

(Same argument for other PaaS solutions)

Example Distributed System: Minified

No Man (Microservice) is an Island

It’s excellent to be able to implement a microservice really easily (Spring Boot), but building a system that way surfaces "non-functional" requirements that you otherwise didn’t have.

There are laws of physics that make some problems unsolvable (consistency, latency), but brittleness and manageability can be addressed with generic, boiler plate patterns.

Emergent features of micro-services systems

Coordination of distributed systems leads to boiler plate patterns

Distributed/versioned configuration
Service registration and discovery
Routing
Service-to-service calls
Load balancing
Circuit Breaker
Asynchronous patterns
Distributed messaging

Spring IO Platform

Example: Coordination Boiler Plate

Netflix OSS

Eureka
Hystrix & Turbine
Ribbon
Feign
Zuul
Archaius
Curator - see Spring Cloud Zookeeper
Asgaard - see Spinnaker (soon)
…

Mikey Cohen Netflix edge architecture, http://goo.gl/M159zi

Example: Spring Cloud and Netflix

Configuration Server

Pluggable source
Git implementation
Versioned
Rollback-able
Configuration client auto-configured via starter

Discovery: Eureka

Service Registration Server
Highly Available
In AWS terms, multi Availability Zone and Region aware

Circuit Breaker: Hystrix

latency and fault tolerance
isolates access to other services
stops cascading failures
enables resilience
circuit breaker pattern
dashboard

Release It!: https://pragprog.com/book/mnee/release-it

Hystrix Observable

@HystrixCommand(fallbackMethod="getDefaultMessage")
public String getMessage() {
  return restTemplate.getForObject(/*...*/);
}

public String getDefaultMessage() {
  return "Hello World Default";
}

// somewhere else
helloService.getMessage();

Circuit Breaker Metrics

Via actuator /metrics
Server side event stream /hystrix.stream
Dashboard app via @EnableHystrixDashboard
Aggregation via Spring Cloud Turbine

Routing: Zuul

JVM based router and filter
Similar routing role as httpd, nginx, or CF go router
Fully programmable rules and filters
Groovy
Java
Any JVM language

Spring Cloud Zuul Proxy

Store routing rules in config server zuul.proxy.route.customers: /customers
Uses Hystrix→Ribbon→Eureka to forward requests to appropriate service

@EnableZuulProxy
@Controller
class Application {
}

Can be used as "sidecar" (or standalone edge server) via @EnableSidecar

Developer Experience

As a microservice developer, I want to write code and run it locally, but have a hight confidence that it will work in the target system.

Stubbing and contract-driven development
Remote debugging, e.g. Spring Boot live reload
Register local app with remote service catalog