带Spring Boot的测微器添加自定义指标来计算用户注册数量

import io.micrometer.core.instrument.MeterRegistry;
import io.micrometer.core.instrument.binder.MeterBinder;

public class UserRegistrationMetrics implements MeterBinder {
    
    private final UserRepository userRepository;
    
    public UserRegistrationMetrics(UserRepository userRepository) {
        this.userRepository = userRepository;
    }
    
    @Override
    public void bindTo(MeterRegistry registry) {
        registry.gauge("user.registration.count", userRepository, UserRepository::count);
    }
}

import org.springframework.boot.actuate.autoconfigure.metrics.MeterRegistryCustomizer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MetricsConfig {
    
    @Bean
    public UserRegistrationMetrics userRegistrationMetrics(UserRepository userRepository) {
        return new UserRegistrationMetrics(userRepository);
    }
    
    @Bean
    public MeterRegistryCustomizer<MeterRegistry> metricsCommonTags() {
        return registry -> registry.config().commonTags("application", "user-registration");
    }
}

import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Long> {
    
    long count();
}