Spring Boot "Failed to configure a DataSource: url attribute is not specified" - Fix in CI

Spring Boot tried to autoconfigure a DataSource but you gave it no spring.datasource.url and there is no embedded database (H2/HSQLDB/Derby) on the classpath for it to fall back to.

What this error means

Startup or a @SpringBootTest fails with Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured. followed by an action suggesting you set the URL or add an embedded database.

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APPLICATION FAILED TO START
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Description:

Failed to configure a DataSource: 'url' attribute is not specified and no
embedded datasource could be configured.

Reason: Failed to determine a suitable driver class

Common causes

No JDBC URL is set in the CI profile

The local profile points at a real database but the CI run has no spring.datasource.url, so autoconfiguration has nothing to connect to.

No embedded database on the test classpath

Without H2/HSQLDB as a test dependency, Spring cannot fall back to an in-memory DataSource for the test context.

DataSource autoconfiguration loaded when it should not be

A test that does not need persistence still triggers DataSourceAutoConfiguration, demanding a URL it has no reason to provide.

How to fix it

Add an embedded database for tests

Put H2 on the test classpath so Spring autoconfigures an in-memory DataSource in CI.

<dependency>
  <groupId>com.h2database</groupId>
  <artifactId>h2</artifactId>
  <scope>test</scope>
</dependency>

Set the datasource URL in the CI profile

If tests hit a real database (e.g. Testcontainers), provide the URL via the active profile or env.

# application-test.yml
spring:
  datasource:
    url: jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1
    driver-class-name: org.h2.Driver

Exclude DataSource autoconfig when persistence is not needed

For tests with no database, exclude the autoconfiguration so no URL is required.

@SpringBootTest
@EnableAutoConfiguration(exclude = DataSourceAutoConfiguration.class)
class NoDbTest { /* ... */ }

How to prevent it

• Add H2 as a test dependency for any app that autoconfigures a DataSource.
• Keep a dedicated test profile with an explicit in-memory or Testcontainers URL.
• Exclude DataSourceAutoConfiguration in slices that do not touch persistence.

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