Integration testing of a Spring Cloud application with the AWS Parameter Store

Question

How to perform integration testing of a Spring Boot application reading properties from the AWS Parameter Store (dependency org.springframework.cloud:spring-cloud-starter-aws-parameter-store-config).

Should the AWS Parameter Store integration be disabled in integration tests?

How to use local server (or mock) instead of the real AWS Parameter Store in integration tests?

Answer 1

Usually integration with the AWS Parameter Store should be disabled in integration tests for simplicity and performance. Instead, load test properties from a file (e.g., src/test/resources/test.properties)

@SpringBootTest(properties = "aws.paramstore.enabled=false")
@TestPropertySource("classpath:/test.properties")
public class SampleTests {
  //...
}

If individual tests need to check integration with the AWS Parameter Store use Testcontainers and LocalStack an easy-to-use local AWS cloud stack for Docker.

Add a configuration class creating custom ssmClient bean of type AWSSimpleSystemsManagement configured to use LocalStack instead of a default one declared in org.springframework.cloud.aws.autoconfigure.paramstore.AwsParamStoreBootstrapConfiguration using the real AWS Parameter Store.

@Configuration(proxyBeanMethods = false)
public class AwsParamStoreBootstrapConfiguration {

  public static final LocalStackContainer AWS_SSM_CONTAINER = initContainer();

  public static LocalStackContainer initContainer() {
    LocalStackContainer container = new LocalStackContainer().withServices(SSM);
    container.start();
    Runtime.getRuntime().addShutdownHook(new Thread(container::stop));
    return container;
  }

  @Bean
  public AWSSimpleSystemsManagement ssmClient() {
    return AWSSimpleSystemsManagementClientBuilder.standard()
        .withEndpointConfiguration(AWS_SSM_CONTAINER.getEndpointConfiguration(SSM))
        .withCredentials(AWS_SSM_CONTAINER.getDefaultCredentialsProvider())
        .build();
  }
}

As far as AwsParamStorePropertySourceLocator is a loaded by a Spring Cloud "bootstrap" context, you need to add a configuration class to the bootstrap context by adding to the file src/test/resources/META-INF/spring.factories the following entry

org.springframework.cloud.bootstrap.BootstrapConfiguration=\
com.example.test.AwsParamStoreBootstrapConfiguration

The same approach can be used for mocking ssmClient using Mockito.