Build resilient systems with Spring Cloud Contract and Testcontainers

Verifying behaviors of the cloud-native applications and ensuring that all of the services in the system work correctly together is both crucial and challenging. Manually maintaining environments to test the correctness of the entire system is undevops-like and fragile.

Luckily, modern tools can help you to build automated, reliable test pipelines, and in this session, we explore how using Spring Cloud Contract and Testcontainers together can improve your testing and deployment processes.

Spring Cloud Contract is an implementation of Consumer-Driven Contracts, an approach that provides a way to easily describe and verify APIs, at the same time allowing building API backward compatibility verification into the deployment process.

Testcontainers lets developers programmatically build test environments consisting of real services running in lightweight and disposable containers. It turns the process of integration testing into a seamless, unit-test-like experience.

In this presentation, we’ll show how contract and integration tests complement each other and explore one of the most natural and reliable approaches to service evolution with contract testing. We’ll discuss why in Spring Cloud Contract, we’ve decided to switch to using Testcontainers as the solution for Kafka and AMQP messaging verification and demonstrate practical use-cases and code examples of how to set up both types of tests in your applications and deployment pipelines.

Transcript

1. Olga Maciaszek-Sharma
   Oleg Šelajev
   May 2023
   Build resilient systems with Spring
   Cloud Contract and Testcontainers
   Copyright © 2023 VMware, Inc. or its affiliates.
   

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2. What is going to happen?
   

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3. About Olga
   Senior Software Engineer in Spring Cloud Team
   ● Spring Cloud LoadBalancer (Spring Cloud Commons)
   ● Spring Interface Clients
   ● Spring Cloud Contract
   ● Spring Cloud OpenFeign
   ● Spring Cloud Netflix
   ● Spring Native support for Spring Cloud projects
   ● RSocket HTTP Bridge
   https://github.com/OlgaMaciaszek
   https://twitter.com/olga_maciaszek
   

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4. Developer advocate at AtomicJar
   ● Testcontainers for Java
   https://github.com/shelajev
   https://twitter.com/shelajev
   About Oleg
   

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5. Our project
   

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6. A new message
   topic: servings
   body:
   { "beverages": [
   {
   "uuid": "16b439a4-6ace-4901-8fb6-728588c12da8",
   "coffee": {
   "name": "Latte",
   "coffeeContent": 60,
   "steamedMilkContent": 180,
   "milkFoamContent": 5
   }
   }
   // …
   ]
   }
   headers:
   “contentType”: “application/json”
   “testKey1”: “testValue1”
   

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7. A new message
   

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8. We go to production!
   Production
   

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9. A new message
   topic: servings
   body:
   { "beverages": [
   {
   "uuid": "16b439a4-6ace-4901-8fb6-728588c12da8",
   "coffee": {
   "name": "Latte",
   "coffeeContent": 60,
   "steamedMilkContent": 180,
   "milkFoamContent": 5
   }
   }
   // …
   ]
   }
   headers:
   “contentType”: “application/json”
   “testKey1”: “testValue1”
   

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10. A new message
    topic: serving
    body:
    { "beverages": [
    {
    "uuid": "16b439a4-6ace-4901-8fb6-728588c12da8",
    "coffee": {
    "name": "Latte",
    "coffeeContent": 60,
    "steamedMilkContent": 180,
    "milkFoamContent": 5
    }
    }
    // …
    ]
    }
    headers:
    “contentType”: “application/json”
    “testKey1”: “testValue1”
    

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11. A new message
    topic: servings
    body:
    { "beverages": [
    {
    "uuid": "16b439a4-6ace-4901-8fb6-728588c12da8",
    "coffee": {
    "name": "Latte",
    "coffeeContent": 60,
    "steamedMilkContent": 180,
    "milkFoamContent": 5
    }
    }
    // …
    ]
    }
    headers:
    “contentType”: “application/json”
    “testKey1”: “testValue1”
    

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12. A new message
    topic: servings
    body:
    { "beverages": [
    {
    "id": "16b439a4-6ace-4901-8fb6-728588c12da8",
    "coffee": {
    "name": "Latte",
    "coffeeContent": 60,
    "steamedMilkContent": 180,
    "milkFoamContent": 5
    }
    }
    // …
    ]
    }
    headers:
    “contentType”: “application/json”
    “testKey1”: “testValue1”
    

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13. A new message
    topic: servings
    body:
    { "beverages": [
    {
    "uuid": "16b439a4-6ace-4901-8fb6-728588c12da8",
    "coffee": {
    "name": "Latte",
    "coffeeContent": 60,
    "steamedMilkContent": 180,
    "milkFoamContent": 5
    }
    }
    // …
    ]
    }
    headers:
    “contentType”: “application/json”
    “testKey1”: “testValue1”
    

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14. A new message
    topic: servings
    body:
    { "beverages": [
    {
    "uuid": "16b439a4-6ace-4901-8fb6-728588c12da8",
    "coffee": {
    "name": "Latte",
    "coffeeContent": 60,
    "steamedMilkContent": 180,
    "milkFoamContent": 5
    }
    }
    // …
    ]
    }
    headers:
    “contentType”: “application/json”
    “testKey1”: “testValue1”
    

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15. Stubs alone don’t guarantee
    ANYTHING
    

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16. The Answer:
    Consumer-Driven Contracts
    

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17. Spring Cloud Contract
    

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18. No free stubs!
    Build tool
    plugin
    Contract
    definitions
    Generated
    tests
    Stubs
    Test setup
    configuration
    

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19. Producer Build Setup
    
    
    
    org.springframework.cloud
    spring-cloud-contract-maven-plugin
    4.0.3-SNAPSHOT
    true
    
    JUNIT5
    io.xxx.BaseTestClass
    
    
    
    org.springframework.boot
    spring-boot-maven-plugin
    
    
    
    

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20. ● Setup the environment
    ● Create inputs
    ● Produce the outputs (with production code)
    Producer test setup
    

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22. ● TC slide
    

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23. ● TC slide
    

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24. No free stubs!
    Build tool
    plugin
    Contract
    definitions
    Generated
    tests
    Stubs
    Test setup
    configuration
    

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25. Contract
    Contract.make {
    label("serving")
    input {
    triggeredBy("triggerServing()")
    }
    / ...
    }
    

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26. Contract
    Contract.make {
    / ...
    outputMessage {
    sentTo("servings")
    body([beverages:
    [[uuid : $(anyUuid()),
    coffee: [
    name : "Latte",
    coffeeContent : "60",
    steamedMilkContent: "180",
    milkFoamContent : "5"
    ]]]])
    / ...
    }
    

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27. Contract
    Contract.make {
    / ...
    headers {
    messagingContentType(applicationJson())
    header 'testKey1', 'testValue1'
    }
    }
    

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28. No free stubs!
    Build tool
    plugin
    Contract
    definitions
    Generated
    tests
    Stubs
    Test setup
    configuration
    

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29. Generated Contract Test
    @Test
    public void validate_shouldSendServing() throws Exception {
    // when:
    triggerServing();
    // then:
    ContractVerifierMessage response = contractVerifierMessaging.receive("servings",
    contract(this, "shouldSendServing.yml"));
    assertThat(response).isNotNull();
    // and:
    assertThat(response.getHeader("contentType")).isNotNull();
    assertThat(response.getHeader("contentType").toString()).isEqualTo("application/json");
    assertThat(response.getHeader("testKey1")).isNotNull();
    assertThat(response.getHeader("testKey1").toString()).isEqualTo("testValue1");
    // ...
    

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30. Generated Contract Test
    @Test
    public void validate_shouldSendServing() throws Exception {
    // ...
    DocumentContext parsedJson =
    JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.getPayload()));
    assertThatJson(parsedJson).array("['beverages']").contains("['uuid']")
    .matches("[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}")
    assertThatJson(parsedJson).array("['beverages']").field("['coffee']").field("['name']")
    .isEqualTo("Latte");
    assertThatJson(parsedJson).array("['beverages']").field("['coffee']").field("['coffeeContent']
    ")
    .isEqualTo("60");
    assertThatJson(parsedJson).array("['beverages']").field("['coffee']").field("['steamedMilkCont
    ent']")
    .isEqualTo("180");
    assertThatJson(parsedJson).array("['beverages']").field("['coffee']").field("['milkFoamContent
    ']")
    .isEqualTo("5");
    

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31. No free stubs!
    Build tool
    plugin
    Contract
    definitions
    Generated
    tests
    Stubs
    Test setup
    configuration
    

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32. Contracts vs Schemas
    

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33. Consumer integration tests
    using stubs from Contract and
    TestContainers
    

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35. Local Development Environment
    

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36. Teamwork - different approaches
    Provider Contracts
    ● Contracts with the producer
    ● The producer has no knowledge
    of how consumers use their API
    ● The producer can impose contract
    changes on consumers
    Consumer Contracts
    ● Contracts with the consumers
    ● Possible issues with conflict
    resolution in case of multiple
    consumers
    ● In some implementations, the
    consumers can impose contract
    changes on the producer
    Consumer-Driven Contracts
    ● Contracts with the producer
    ○ If security issues, an
    external repo
    ● Consumers as key participants in
    the creation of the contracts
    ● Convenient handling of multiple
    consumers
    

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37. Spring Cloud Contract - Consumer-Driven Contract Flow
    Consumer
    ● Checks out Producer code repo and works
    locally on a contract
    ● Creates a pull request with the new Contract
    ● Collaborates with the Producer on the Contract
    PR
    ● Uses stubs published by the producer along the
    app for integration tests
    Producer
    ● Reviews the Contract PR
    ● Runs build on the PR branch (FAILURE)
    ● Adds required endpoints
    ● Runs build on the PR branch (PASSING)
    ● Code Deployed along with generated stubs jar
    

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38. Spring Cloud Contract - Consumer-Driven Contract Flow
    Consumer
    ● Checks out Producer code repo and works
    locally on a contract
    ● Creates a pull request with the new Contract
    ● Collaborates with the Producer on the Contract
    PR
    ● Uses stubs published by the producer along the
    app for integration tests
    Producer
    ● Reviews the Contract PR
    ● Runs build on the PR branch (FAILURE)
    ● Adds required endpoints
    ● Runs build on the PR branch (PASSING)
    ● Code Deployed along with generated stubs jar
    

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39. Spring Cloud Contract - Consumer-Driven Contract Flow
    Consumer
    ● Checks out Producer code repo and works
    locally on a contract
    ● Creates a pull request with the new Contract
    ● Collaborates with the Producer on the Contract
    PR
    ● Uses stubs published by the producer along the
    app for integration tests
    Producer
    ● Reviews the Contract PR
    ● Runs build on the PR branch (FAILURE)
    ● Adds required endpoints
    ● Runs build on the PR branch (PASSING)
    ● Code Deployed along with generated stubs jar
    

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40. Spring Cloud Contract - Consumer-Driven Contract Flow
    Consumer
    ● Checks out Producer code repo and works
    locally on a contract
    ● Creates a pull request with the new Contract
    ● Collaborates with the Producer on the Contract
    PR
    ● Uses stubs published by the producer along the
    app for integration tests
    Producer
    ● Reviews the Contract PR
    ● Runs build on the PR branch (FAILURE)
    ● Adds required endpoints
    ● Runs build on the PR branch (PASSING)
    ● Code Deployed along with generated stubs jar
    

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41. Spring Cloud Contract - Consumer-Driven Contract Flow
    Consumer
    ● Checks out Producer code repo and works
    locally on a contract
    ● Creates a pull request with the new Contract
    ● Collaborates with the Producer on the Contract
    PR
    ● Uses stubs published by the producer along the
    app for integration tests
    Producer
    ● Reviews the Contract PR
    ● Runs build on the PR branch (FAILURE)
    ● Adds required endpoints
    ● Runs build on the PR branch (PASSING)
    ● Code Deployed along with generated stubs jar
    

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42. Spring Cloud Contract - Consumer-Driven Contract Flow
    Consumer
    ● Checks out Producer code repo and works
    locally on a contract
    ● Creates a pull request with the new Contract
    ● Collaborates with the Producer on the Contract
    PR
    ● Uses stubs published by the producer along the
    app for integration tests
    Producer
    ● Reviews the Contract PR
    ● Runs build on the PR branch (FAILURE)
    ● Adds required endpoints
    ● Runs build on the PR branch (PASSING)
    ● Code Deployed along with generated stubs jar
    

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43. Spring Cloud Contract - Consumer-Driven Contract Flow
    Consumer
    ● Checks out Producer code repo and works
    locally on a contract
    ● Creates a pull request with the new Contract
    ● Collaborates with the Producer on the Contract
    PR
    ● Uses stubs published by the producer along the
    app for integration tests
    Producer
    ● Reviews the Contract PR
    ● Runs build on the PR branch (FAILURE)
    ● Adds required endpoints
    ● Runs build on the PR branch (PASSING)
    ● Code Deployed along with generated stubs jar
    

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44. Spring Cloud Contract - Consumer-Driven Contract Flow
    Consumer
    ● Checks out Producer code repo and works
    locally on a contract
    ● Creates a pull request with the new Contract
    ● Collaborates with the Producer on the Contract
    PR
    ● Uses stubs published by the producer along the
    app for integration tests
    Producer
    ● Reviews the Contract PR
    ● Runs build on the PR branch (FAILURE)
    ● Adds required endpoints
    ● Runs build on the PR branch (PASSING)
    ● Code Deployed along with generated stubs jar
    

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46. Backward Compatibility Checks in Pipelines
    New API version
    Test with PROD
    contracts
    Deploy
    Test with new
    contracts
    

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47. Producer Build Setup - Compatibility Tests with Profiles
    
    apicompatibility
    
    
    
    org.springframework.cloud
    spring-cloud-contract-maven-plugin
    4.0.3-SNAPSHOT
    
    ${repo.with.binaries}
    REMOTE
    
    ${project.groupId}
    ${project.artifactId}
    stubs
    ${latest.production.version}
    
    
    
    
    
    
    

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48. Evolving the system safely
    Deployment Contract fields Producer fields
    0
    {
    "uuid": "xxx"
    }
    {
    "uuid": "xxx"
    }
    1
    {
    "uuid": "xxx",
    "id": 5
    }
    {
    "uuid": “xxx”,
    "id": 5
    }
    2
    {
    "id": 5
    }
    {
    "uuid": “xxx”,
    "id": 5
    }
    3
    {
    "id": 5
    }
    {
    "id": 5
    }
    

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49. What’s next?
    github.com/OlgaMaciaszek/coffee
    testcontainers.com
    https://docs.spring.io/spring-cloud-contract/docs/current/reference/html/
    

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