Integration testing with Docker Compose and JUnit

Dariusz Lorenc Boris Kravtsov

Pivotal Labs

Problem

End-2-end test of GemFire in various cluster configurations and with different failover scenarios

GemFire

GemFire is a distributed, in-memory database with strong data consistency, built to support transactional applications with low latency

and high concurrency needs

GemFire Server

GemFire

GemFire Server GemFire Server

Partitioned Data

Partitioned Data

Partitioned Data

GemFire Server GemFire Server GemFire Server

Partitioned Data

Partitioned Data

Partitioned Data

Client

WAN / Multi-Site

Gateway Hub

Gateway Hub

Relational Database

Docker Compose to the rescue

Docker Compose is a tool for defining and running multi-container Docker applications

Docker Compose JUnit Rule

A JUnit rule to manage docker containers using docker-compose

• Start and stop docker-compose multi-container applications

• Waits for services to become available before running tests

• Extends logging and debugging

https://github.com/palantir/docker-compose-rule

GreetingCounter

Master

Our Sample Distributed System

Test First - Happy Path

@Test public void shouldReturnData(){ get("/info") .then().assertThat() .body("counter", isA(Number.class)) .body("greeting", is("Hello World")); }

Spring Boot - Application.kt

@SpringBootApplication open class Application { companion object { @JvmStatic fun main(args: Array<String>) { SpringApplication.run(Application::class.java, *args) } } }

Greeting Service

@RestController class Controller { @RequestMapping("/greeting") fun greet(): Greeting { return Greeting("Hello World") } }

data class Greeting(val greeting: String)

Counter Service

@RestController class Controller { val counter = AtomicLong() @RequestMapping("/counter") fun count(): Counter { return Counter(counter.incrementAndGet()) } }

data class Counter(val counter: Long)

Master Service

@RestController class Controller @Autowired constructor( val greetingClient: GreetingClient, val counterClient: CounterClient) { @RequestMapping("/info") fun info(): Response { return Response(counterClient.counter().counter, greetingClient.greeting().greeting) } }

data class Response(val counter: Long, val greeting: String)

Master Service - Greeting Client

@FeignClient(name = "greeting", url = "http://greeting-service:8080") interface GreetingClient { @RequestMapping(value = "/greeting", method = arrayOf(RequestMethod.GET)) fun greeting(): Greeting }

Master Service - Counter Client

@FeignClient(name = "counter", url = "http://counter-service:8080") interface CounterClient { @RequestMapping(value = “/counter”, method = arrayOf(RequestMethod.GET)) fun counter(): Counter }

GreetingCounter

Master

Next Step: Dockerize Our Services

Dockerfiles

FROM frolvlad/alpine-oraclejdk8:slim

ADD master-service-1.0.0.jar app.jar

EXPOSE 8080

ENTRYPOINT ["java","-jar","/app.jar"]

Base image

Add the app’s fat jar

Expose the port

Start the java app

Build Docker Image with Gradle (Transmodo plugin)

buildscript { dependencies { classpath('se.transmode.gradle:gradle-docker:1.2') } } group = '<your docker group name>' apply plugin: 'docker' task buildDocker(type: Docker, dependsOn: build) { push = true applicationName = jar.baseName dockerfile = file('src/main/docker/Dockerfile') doFirst { copy { from jar into stageDir } } }

Gradle Docker plugin

Your Docker Hub ID

Build Docker task

GreetingCounter

MasterGreetingCount

“Docker Composed” Services

Docker Compose

docker-compose.ymlGreeting

Counter

Master

greeting-service: image: lorenc/greeting-service ports: - “8081:8080" counter-service: image: lorenc/counter-service ports: - "8082:8080" master-service: image: lorenc/master-service ports: - "8083:8080" links: - greeting-service - counter-service

Integration Test Setup

@Rule public DockerComposeRule docker = DockerComposeRule.builder() .file("../docker-compose.yml") .build();

@Before public void setUp() throws Exception { docker.dockerCompose().up(); } @After public void tearDown() throws Exception { docker.dockerCompose().down(); }

Health Checks & Logs

@Rule public DockerComposeRule docker = DockerComposeRule.builder() .file("../docker-compose.yml") .waitingForService("greeting-service", toRespondOverHttp(8080, TO_EXTERNAL_URI)) .waitingForService("counter-service", toRespondOverHttp(8080, TO_EXTERNAL_URI)) .waitingForService("master-service", toRespondOverHttp(8080, TO_EXTERNAL_URI)) .saveLogsTo("build/docker-logs") .build();

What could possibly go wrong?

@Test public void shouldReturnHolaWhenGreetingServiceDown(){ docker.dockerCompose().container("greeting-service").stop(); get("/info") .then().assertThat() .body("greeting", is("Hola!")); }

What could possibly go wrong?

@Test public void shouldReturn42WhenCounterServiceDown() { docker.dockerCompose().container("counter-service").stop(); get("/info") .then().assertThat() .body("counter", is(42)); }

@FeignClient(name = "greeting", url = "http://greeting-service:8080", fallback = DefaultGreeting::class) interface GreetingClient { @RequestMapping(value = "/greeting", method = arrayOf(RequestMethod.GET)) fun greeting(): Greeting }

@Component class DefaultGreeting : GreetingClient { override fun greeting(): Greeting { return Greeting("Hola!") } }

Master Service - Greeting Client

Master Service - Counter Client@FeignClient(name = "counter", url = "http://counter-service:8080", fallback = DefaultCounter::class) interface CounterClient { @RequestMapping(value = “/counter”, method = arrayOf(RequestMethod.GET)) fun counter(): Counter }

@Component class DefaultCounter : CounterClient { override fun counter(): Counter { return Counter(42) } }

Demo

References https://github.com/d-lorenc/junit-docker-demo https://github.com/palantir/docker-compose-rule