Database / Liquibase interview questions
How do you use Liquibase with Docker and Testcontainers in integration tests?
Testcontainers is a Java library that spins up real Docker containers during JUnit tests, providing actual database instances instead of in-memory databases. Combining Testcontainers with Liquibase gives you integration tests that run against a realistic database — same engine type, same version — with an auto-migrated schema, without any manual database setup.
Maven dependency:
<dependency> <groupId>org.testcontainers</groupId> <artifactId>postgresql</artifactId> <version>1.19.3</version> <scope>test</scope> </dependency>
JUnit 5 test with Spring Boot and Testcontainers:
@SpringBootTest @Testcontainers class OrderRepositoryIntegrationTest { @Container static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:16") .withDatabaseName("testdb") .withUsername("test") .withPassword("test"); @DynamicPropertySource static void postgresProperties(DynamicPropertyRegistry registry) { registry.add("spring.datasource.url", postgres::getJdbcUrl); registry.add("spring.datasource.username", postgres::getUsername); registry.add("spring.datasource.password", postgres::getPassword); } // Spring Boot auto-runs Liquibase on startup using the dynamic datasource URL // By the time @Test methods run, all changeSets are applied @Autowired OrderRepository orderRepository; @Test void shouldSaveAndRetrieveOrder() { Order order = new Order("customer-1", BigDecimal.valueOf(99.99)); orderRepository.save(order); assertThat(orderRepository.findById(order.getId())).isPresent(); } }
When Spring Boot starts with the dynamic Testcontainers URL, it auto-runs Liquibase migrations before the test context is ready. By the time @Test methods execute, the schema is fully migrated. The container is stopped and removed after the test class completes.
When in the Spring Boot application lifecycle does Liquibase run migrations in a Testcontainers integration test?
What annotation makes Spring Boot read the dynamic Testcontainers JDBC URL at startup?
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