How to reuse Testcontainers between multiple SpringBootTests?

Question

I'm using TestContainers with Spring Boot to run unit tests for repositories like this:

@Testcontainers
@ExtendWith(SpringExtension.class)
@ActiveProfiles("itest")
@SpringBootTest(classes = RouteTestingCheapRouteDetector.class)
@ContextConfiguration(initializers = AlwaysFailingRouteRepositoryShould.Initializer.class)
@TestExecutionListeners(listeners = DependencyInjectionTestExecutionListener.class)
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
@Tag("docker")
@Tag("database")
class AlwaysFailingRouteRepositoryShould {

  @SuppressWarnings("rawtypes")
  @Container
  private static final PostgreSQLContainer database =
      new PostgreSQLContainer("postgres:9.6")
          .withDatabaseName("database")
          .withUsername("postgres")
          .withPassword("postgres");

But now I have 14 of these tests and every time a test is run a new instance of Postgres is spun up. Is it possible to reuse the same instance across all tests? The Singleton pattern doesn't help since every test starts a new application.

I've also tried testcontainers.reuse.enable=true in .testcontainers.properties and .withReuse(true), but that didn't help.

Solution 1

You can't use the JUnit Jupiter annotation @Container if you want to have reusable containers. This annotation ensures to stop the container after each test.

What you need is the singleton container approach, and use e.g. @BeforeAll to start your containers. Even though you then have .start() in multiple tests, Testcontainers won't start a new container if you opted-in for reusability using both .withReuse(true) on your container definition AND the following .testcontainers.properties file in your home directory:

testcontainers.reuse.enable=true

A simple example might look like the following:

@SpringBootTest
public class SomeIT {

  public static GenericContainer postgreSQLContainer = new PostgreSQLContainer().
    withReuse(true);

  @BeforeAll
  public static void beforeAll() {
    postgreSQLContainer.start();
  }

  @Test
  public void test() {

  }

}

and another integration test:

@SpringBootTest
public class SecondIT {

  public static GenericContainer postgreSQLContainer = new PostgreSQLContainer().
    withReuse(true);

  @BeforeAll
  public static void beforeAll() {
    postgreSQLContainer.start();
  }

  @Test
  public void secondTest() {

  }

}

There is currently a PR that adds documentation about this

I've put together a blog post explaining how to reuse containers with Testcontainers in detail.

Solution 2

If you decide go forward with the singleton pattern, mind the warning in "Database containers launched via JDBC URL scheme". I took hours till I note that, even though I was using the singleton pattern, an additional container was always being created mapped on a different port.

In summary, do not use the test containers JDBC (host-less) URIs, such as jdbc:tc:postgresql:<image-tag>:///<databasename>, if you need use the singleton pattern.

Comments

[Martin Schröder]

"The Singleton pattern doesn't help since every test starts a new application."

[Martin Schröder]

Many thanks. Then I also need to increase my max_connections with .withCommand("postgres -c max_connections=200"). How can I control the lifetime of reusable containers?

[rieckpil]

I can't answer this question. Maybe it's worth having a look at the PR which introduced the feature: github.com/testcontainers/testcontainers-java/pull/1781

[Abbadon]

Where is testcontainers.reuse.enable=true documented?

[vault]

Is there a way to configure testcontainers.reuse.enable=true elsewhere? I don't want reusable containers to be dependant on the developer's laptop configuration

[rieckpil]

Yes, there are multiple ways to configure this property. Take a look at the Configuration locations section of the Testcontainers documentation.

[Yaroslav Buhaiev]

You can't set testcontainers.reuse.enable via classpath. See this comment.

[Gaurav Parek]

@rieckpil how can we ensure that it is reusing the same container as I applied these settings and I do not see any time difference in my integration test run time. it seems to same with these conditions enabled and disabled. thanks

[rieckpil]

Take a look at docker ps while your tests are running. You should only see a single container being used. If you are on Linux/macOS watch -n 1 docker ps may be handy

[Frankie Drake]

@vault You can do this via TestcontainersConfiguration.getInstance().updateUserConfig("‌​testcontainers.reuse‌​.enable", "true"); before starting the container

[gstackoverflow]

There are 2 calls of new PostgreSQLContainer() But only one container will be used. Is it correct ?

[rieckpil]

Yes, only one container will be created for the tests