I’ve been building Spring Boot applications for years, and one pattern keeps recurring - repeatedly configuring the same components across different projects. That constant setup time adds up. Why not package that reusable logic into something shareable? That’s exactly what led me down the path of creating custom Spring Boot starters. Today, I’ll walk you through building your own starter with auto-configuration, just like the official Spring Boot ones you use daily.

Let’s start with the core concept. Spring Boot starters simplify dependency management and automatic configuration. When you create a custom starter, you’re essentially packaging your team’s best practices into a single dependency. Think about it - how many times have you copied cache configurations between projects? What if you could install your caching solution as easily as adding spring-boot-starter-data-jpa?

We’ll build a “Smart Cache” starter together. This starter will handle intelligent caching with metrics, health checks, and configurable eviction policies. The project needs two modules: an auto-configuration module containing the core logic, and a starter module for dependency management. Here’s how the structure looks:

smart-cache-spring-boot-starter/
├── smart-cache-spring-boot-autoconfigure/
│   ├── src/main/java/
│   ├── src/main/resources/
│   └── pom.xml
└── smart-cache-spring-boot-starter/
    └── pom.xml

First, create the parent POM to manage both modules:

<project>
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>3.2.0</version>
  </parent>
  
  <groupId>com.example</groupId>
  <artifactId>smart-cache-parent</artifactId>
  <version>1.0.0</version>
  <packaging>pom</packaging>
  
  <modules>
    <module>smart-cache-autoconfigure</module>
    <module>smart-cache-starter</module>
  </modules>
  
  <properties>
    <java.version>17</java.version>
  </properties>
</project>

Now, the auto-configuration module does the heavy lifting. Notice how we conditionally enable features based on classpath presence - this prevents errors when dependencies are missing. How might we ensure our cache behaves differently in test environments?

@Configuration
@ConditionalOnClass(CacheManager.class)
@EnableConfigurationProperties(SmartCacheProperties.class)
public class SmartCacheAutoConfiguration {
  
  @Bean
  @ConditionalOnMissingBean
  public CacheManager cacheManager(SmartCacheProperties properties) {
    SmartCacheManager cacheManager = new SmartCacheManager();
    cacheManager.setMaxSize(properties.getMaxSize());
    cacheManager.setTtl(properties.getTimeToLive());
    return cacheManager;
  }
  
  @Bean
  @ConditionalOnProperty(name = "smart-cache.metrics-enabled", havingValue = "true")
  @ConditionalOnClass(MeterRegistry.class)
  public SmartCacheMetrics smartCacheMetrics(MeterRegistry registry) {
    return new SmartCacheMetrics(registry);
  }
}

Configuration properties make your starter customizable. Users configure your component using familiar application.yml syntax. What if we want to add tiered caching later?

@ConfigurationProperties(prefix = "smart-cache")
public class SmartCacheProperties {
  private boolean enabled = true;
  private int maxSize = 1000;
  private Duration timeToLive = Duration.ofMinutes(30);
  
  // Getters and setters
}

Don’t forget the spring.factories file in src/main/resources/META-INF - this registers your auto-configuration:

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.example.smartcache.autoconfigure.SmartCacheAutoConfiguration

The starter module itself is minimal - just a POM that brings in the auto-configuration module and its required dependencies:

<project>
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <artifactId>smart-cache-parent</artifactId>
    <groupId>com.example</groupId>
    <version>1.0.0</version>
  </parent>
  
  <artifactId>smart-cache-starter</artifactId>
  
  <dependencies>
    <dependency>
      <groupId>com.example</groupId>
      <artifactId>smart-cache-autoconfigure</artifactId>
      <version>${project.version}</version>
    </dependency>
  </dependencies>
</project>

Testing is crucial. Verify your auto-configuration behaves correctly under different conditions. This test confirms our cache manager only loads when properties are enabled:

@SpringBootTest
class SmartCacheAutoConfigurationTest {
  
  @Autowired(required = false)
  private CacheManager cacheManager;
  
  @Test
  @EnableAutoConfiguration
  void whenPropertiesEnabled_thenCacheManagerCreated() {
    assertThat(cacheManager).isNotNull();
  }
  
  @Test
  @SpringBootApplication(exclude = SmartCacheAutoConfiguration.class)
  void whenManuallyExcluded_thenCacheManagerNotCreated() {
    assertThat(cacheManager).isNull();
  }
}

Now developers can use your starter by simply adding it to their POM. They configure it through standard application.properties:

smart-cache.max-size=5000
smart-cache.time-to-live=1h
smart-cache.metrics-enabled=true

Creating custom starters has transformed how my teams share infrastructure code. Instead of copying configurations between projects, we maintain standardized components. Have you identified any repetitive configurations in your current projects that could become starters?

Building your own Spring Boot starters might seem complex at first, but the payoff in maintainability and consistency is immense. If you implement this pattern, you’ll find yourself spending less time on boilerplate and more time solving actual business problems. Found this useful? Share it with your team and leave a comment about what starter you’ll build first!