How does one go about doing end-to-end testing of a distributed in-memory database such as Pivotal GemFire? Presented at JVM Meetup Sydney https://www.meetup.com/Sydney-JVM-Community/events/233465115/ Demo code available at: https://github.com/d-lorenc/junit-docker-demo

1. Integration testing with Docker Compose and JUnit
Dariusz Lorenc
Boris Kravtsov

2. Pivotal Labs

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

4. GemFire
GemFire is a distributed, in-memory database with strong data
consistency, built to support transactional applications with low latency
and high concurrency needs

5. GemFire Server
GemFire
GemFire Server GemFire Server
Partitioned
Data
Partitioned
Data
Partitioned
Data
GemFire ServerGemFire Server GemFire Server
Partitioned
Data
Partitioned
Data
Partitioned
Data
Client
WAN / Multi-Site
Gateway Hub
Gateway Hub
Relational Database

6. Docker Compose to the rescue
Docker Compose is a tool for defining and running multi-container
Docker applications

7. 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

8. GreetingCounter
Master
Our Sample Distributed System

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

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

11. Greeting Service
@RestController
class Controller {
@RequestMapping("/greeting")
fun greet(): Greeting {
return Greeting("Hello World")
}
}
data class Greeting(val greeting: String)

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

13. 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)

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

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

16. GreetingCounter
Master
Next Step: Dockerize Our Services

17. 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

18. 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

19. GreetingCounter
Master
GreetingCount
“Docker Composed” Services
Docker Compose

20. docker-compose.yml
Greeting
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

21. 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();
}

22. 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();

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

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

26. @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

27. 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)
}
}

28. Demo

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