How to Integrate with Spring Boot¶

Inject feature flag proxies as Spring beans using auto-configuration.

Goal¶

Make all @Feature proxies available for @Autowired injection in Spring components.

Prerequisites¶

Spring Boot 3.x
FlagZen basics: @Feature, @Variant

Steps¶

1. Add the dependency¶

dependencies {
    implementation("com.flagzen:flagzen-spring:1.1.0")
    annotationProcessor("com.flagzen:flagzen-core:1.1.0")
}

2. Define your features and variants (as usual)¶

@Feature("checkout-flow")
public interface CheckoutFlow {
    String execute();
}

@Variant(value = "STREAMLINED", of = CheckoutFlow.class)
public class StreamlinedCheckout implements CheckoutFlow {
    @Override
    public String execute() { return "streamlined"; }
}

3. Inject into your Spring components¶

@Service
public class OrderService {
    @Autowired
    private CheckoutFlow checkoutFlow;

    public String process() {
        return checkoutFlow.execute();
    }
}

The auto-configuration scans for all @Feature-annotated interfaces and registers generated proxies as Spring beans.

4. (Optional) Define a custom FlagProvider bean¶

By default, the auto-configuration uses an in-memory provider (safe for development, but returns empty for all flags). To use environment variables or a custom provider, define a FlagProvider bean:

@Configuration
public class FlagsConfig {
    @Bean
    public FlagProvider flagProvider() {
        return new EnvironmentVariableFlagProvider();
    }
}

The auto-configuration detects your FlagProvider bean and uses it for all proxies.

5. (Optional) Use profile-based configuration¶

Define different providers per environment:

@Configuration
@Profile("production")
public class ProdFlagsConfig {
    @Bean
    public FlagProvider flagProvider() {
        return new EnvironmentVariableFlagProvider();
    }
}

@Configuration
@Profile("test")
public class TestFlagsConfig {
    @Bean
    public FlagProvider flagProvider() {
        InMemoryFlagProvider provider = new InMemoryFlagProvider();
        provider.set("checkout-flow", "STREAMLINED");
        return provider;
    }
}

6. (Optional) Override the FeatureDispatcher bean¶

If you need custom dispatcher logic, define your own FeatureDispatcher bean:

@Configuration
public class FlagsConfig {
    @Bean
    public FlagProvider flagProvider() { ... }

    @Bean
    public FeatureDispatcher featureDispatcher(FlagProvider provider) {
        return FeatureDispatcher.withProvider(provider);
    }
}

The auto-configuration backs off when it detects your custom bean.

Result¶

Feature proxies are available as Spring beans throughout your application context. The dispatcher is shared across all injected proxies, ensuring consistent flag resolution.