Spring Cloud, Spring Boot and Netflix OSS
http://localhost:4000/decks/cloud-boot-netflix.html
Spencer Gibb
twitter: @spencerbgibb
email: sgibb@pivotal.io
Dave Syer
twitter: @david_syer
email: dsyer@pivotal.io
(Spring Boot and Netflix OSS
or Spring Cloud Components)
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Outline
Define microservices
Outline some distributed system problems
Introduce Netflix OSS and its integration with Spring Boot
Spring Cloud demos
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What are micro-services?
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
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Lightweight Services and
REST
There is a strong trend in distributed systems with lightweight
architectures
People have started to call them "microservices"
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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.
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Cloudfoundry
Deploying services needs to be simple and reproducible
$ cf push app.groovy
and you don't get much more convenient than that.
(Same argument for other PaaS solutions)
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Continuous Delivery
Microservices lend themselves to continuous delivery.
You need continuous delivery
Book (Humble and Farley): http://continuousdelivery.com Netflix Blog:
http://techblog.netflix.com/2013/08/deploying-netflix-api.html
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Example Distributed System:
Minified
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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.
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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
Distributed messaging
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Example: Coordination Boiler
Plate
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Bootification
How to bring the ease of Spring Boot to a micro-services architecture?
Netflix OSS
Consul
etcd
zookeeper
custom
doozerd
ha proxy
nginx
Typesafe Config
and many more... what to choose?
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Netflix OSS
Eureka
Hystrix & Turbine
Ribbon
Feign
Zuul
Archaius
Curator
Asgaard
...
Mikey Cohen Netflix edge architecture, http://goo.gl/M159zi
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Example: Spring Cloud and
Netflix
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Configuration Server
Pluggable source
Git implementation
Versioned
Rollback-able
Configuration client auto-configured via starter
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Spring Cloud Configuration
Server
Supports applications <appname>.properties
Supports environments <appname>-<envname>.yml
Default environment application.properties applies to all
applications and environments
DEMO
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Config Client
Consumers of config server can use client library as Spring Boot plugin
Features:
Bootstrap Environment from server
POST to /env to change Environment
@RefreshScope for atomic changes to beans via Spring lifecycle
POST to /refresh
POST to /restart
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Environment Endpoint
POST to /env
Re-binds @ConfigurationProperties
Resets loggers if any logging.level changes are detected
Sends EnvironmentChangeEvent with list of properties that
changed
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Refresh Endpoint
POST to /refresh
Re-loads configuration including remote config server
Re-binds @ConfigurationProperties
Resets @RefreshScope cache
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RefreshScope
Annotate @Beans
Atomic updates during /refresh
DEMO
@EnableConfigurationProperties(MyProps)
public class Application {
@Autowired
private MyProps props
@RefreshScope
@Bean
public Service service() {
new Service(props.name)
}
}
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Restart Endpoint
POST to /restart closes application context and refreshes it
Probably more useful in development than production (leaks?)
Disabled by default
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Encrypted Properties
Authenticated clients have access to unencrypted data.
Only encrypted data is stored in git.
Support for server side or client side decryption
DEMO
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Discovery: Eureka
Service Registration Server
Highly Available
In AWS terms, multi Availability Zone and Region aware
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Eureka Client
Register service instances with Eureka Server
@EnableEurekaClient auto registers instance in server
Eureka Server
Eureka Client
@EnableEurekaClient
public class Application {
}
DEMO
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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
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Declarative Hystrix
Programmatic access is cumbersome
@HystrixCommand to the rescue
@EnableHystrix via starter pom
Wires up spring aop aspect
DEMO
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Hystrix Synchronous
private String getDefaultMessage() {
return "Hello World Default";
}
@HystrixCommand(fallbackMethod="getDefaultMessage")
public String getMessage() {
return restTemplate.getForObject(/*...*/);
}
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Hystrix Future
@HystrixCommand(fallbackMethod="getDefaultMessage")
public Future<String> getMessageFuture() {
return new AsyncResult<String>() {
public String invoke() {
return restTemplate.getForObject(/*...*/);
}
};
}
//somewhere else
service.getMessageFuture().get();
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Hystrix Observable
@HystrixCommand(fallbackMethod="getDefaultMessage")
public Observable<String> getMessageRx() {
return new ObservableResult<String>() {
public String invoke() {
return restTemplate.getForObject(/*...*/);
}
};
}
//somewhere else
helloService.getMessageRx().subscribe(new Observer<String>() {
@Override public void onCompleted() {}
@Override public void onError(Throwable e) {}
@Override public void onNext(String s) {}
});
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Circuit Breaker Metrics
Via actuator /metrics
Server side event stream /hystrix.stream
Dashboard app via @EnableHystrixDashboard
More coming...
DEMO
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Metric Aggregation: Turbine
Aggregator for Hystrix data
Pluggable locator
Static list
Eureka
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Ribbon
Client side load balancer
Pluggable transport
Protocols: http, tcp, udp
Pluggable load balancing algorithms
Round robin, “best available”, random, response time based
Pluggable source for server list
Static list, Eureka!
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Feign
Declarative web service client definition
Annotate an interface
Highly customizable
Encoders/decoders
Annotation processors (Feign, JAX-RS)
Logging
Supports Ribbon and therefore Eureka
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Feign cont.
Auto-configuration
Support for Spring MVC annotations
Uses Spring MessageConverter’s for decoder/encoder
DEMO
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Feign cont.
public interface HelloClient {
@RequestMapping(method = RequestMethod.GET,
value = "/hello")
Message hello();
@RequestMapping(method = RequestMethod.POST,
value = "/hello",
consumes = "application/json")
Message hello(Message message);
}
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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
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How Netflix uses Zuul
Authentication
Insights
Stress Testing
Canary Testing
Dynamic Routing
Service Migration
Load Shedding
Security
Static Response handling
Active/Active traffic management
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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 {
@RequestMapping("/")
String home() {
return 'redirect:/index.html#/customers'
}
}
DEMO
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Configuration: Archaius
Client side configuration library
extends apache commons config
extendible sources
Polling or push updates
DynamicStringProperty myprop = DynamicPropertyFactory.getInstance()
.getStringProperty("my.prop");
someMethod(myprop.get());
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Archaius: Spring Environment
Bridge
Auto-configured
Allows Archaius Dynamic*Properties to find values via Spring
Environment
Existing Netflix libraries configured via application.
{properties,yml} and/or Spring Cloud Config Server
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Spring Cloud Bus
Lightweight messaging bus using spring integration abstractions
spring-amqp, rabbitmq and http
other implementations possible
Send messages to all services or...
To just one applications nodes (ie just service x) ?destination=x
Post to /bus/env sends environment updates
Post to /bus/refresh sends a refresh command
DEMO
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Spring Cloud Starters
spring-cloud-starter spring-cloud-starter-hystrix
spring-cloud-starter-bus-amqp spring-cloud-starter-hystrix-
dashboard
spring-cloud-starter- spring-cloud-starter-turbine
cloudfoundry
spring-cloud-starter-eureka spring-cloud-starter-zuul
spring-cloud-starter-eureka-
server
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Links
http://github.com/spring-cloud
http://github.com/spring-cloud-samples
http://blog.spring.io
http://presos.dsyer.com/decks/cloud-boot-netflix.html
Twitter: @spencerbgibb, @david_syer
Email: sgibb@pivotal.io, dsyer@pivotal.io
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