Metadata Management

@FunctionalInterface
public interface MetadataContributor {
    /**
     * Contribute metadata as key-value pairs
     * @return Map of metadata entries
     */
    Map<String, String> getMetadata();
}

public class StartupDateMetadataContributor implements MetadataContributor {
    @Override
    public Map<String, String> getMetadata();
}

public class CompositeMetadataContributor implements MetadataContributor {
    public CompositeMetadataContributor(List<MetadataContributor> contributors);
    
    @Override
    public Map<String, String> getMetadata();
}

@Component
public class EnvironmentMetadataContributor implements MetadataContributor {
    
    private final Environment environment;
    
    public EnvironmentMetadataContributor(Environment environment) {
        this.environment = environment;
    }
    
    @Override
    public Map<String, String> getMetadata() {
        Map<String, String> metadata = new HashMap<>();
        
        // Add active profiles
        String[] profiles = environment.getActiveProfiles();
        metadata.put("profiles", String.join(",", profiles));
        
        // Add environment-specific info
        metadata.put("environment", environment.getProperty("app.environment", "unknown"));
        metadata.put("version", environment.getProperty("app.version", "unknown"));
        
        return metadata;
    }
}

@Component
public class BuildMetadataContributor implements MetadataContributor {
    
    private final BuildProperties buildProperties;
    
    public BuildMetadataContributor(BuildProperties buildProperties) {
        this.buildProperties = buildProperties;
    }
    
    @Override
    public Map<String, String> getMetadata() {
        Map<String, String> metadata = new HashMap<>();
        
        if (buildProperties != null) {
            metadata.put("build.version", buildProperties.getVersion());
            metadata.put("build.time", buildProperties.getTime().toString());
            metadata.put("build.artifact", buildProperties.getArtifact());
            metadata.put("build.group", buildProperties.getGroup());
        }
        
        return metadata;
    }
}

@Component
public class GitMetadataContributor implements MetadataContributor {
    
    private final GitProperties gitProperties;
    
    public GitMetadataContributor(GitProperties gitProperties) {
        this.gitProperties = gitProperties;
    }
    
    @Override
    public Map<String, String> getMetadata() {
        Map<String, String> metadata = new HashMap<>();
        
        if (gitProperties != null) {
            metadata.put("git.branch", gitProperties.getBranch());
            metadata.put("git.commit.id", gitProperties.getShortCommitId());
            metadata.put("git.commit.time", gitProperties.getCommitTime().toString());
        }
        
        return metadata;
    }
}

@Component
public class SystemMetadataContributor implements MetadataContributor {
    
    @Override
    public Map<String, String> getMetadata() {
        Map<String, String> metadata = new HashMap<>();
        
        // JVM information
        metadata.put("java.version", System.getProperty("java.version"));
        metadata.put("java.vendor", System.getProperty("java.vendor"));
        
        // System information
        metadata.put("os.name", System.getProperty("os.name"));
        metadata.put("os.arch", System.getProperty("os.arch"));
        
        // Runtime information
        Runtime runtime = Runtime.getRuntime();
        metadata.put("jvm.max.memory", String.valueOf(runtime.maxMemory()));
        metadata.put("jvm.processors", String.valueOf(runtime.availableProcessors()));
        
        // Container/hostname info
        try {
            metadata.put("hostname", InetAddress.getLocalHost().getHostName());
        } catch (UnknownHostException e) {
            metadata.put("hostname", "unknown");
        }
        
        return metadata;
    }
}

# Static metadata via properties
spring.boot.admin.client.instance.metadata.environment=production
spring.boot.admin.client.instance.metadata.team=backend
spring.boot.admin.client.instance.metadata.region=us-east-1
spring.boot.admin.client.instance.metadata.version=1.2.3
spring.boot.admin.client.instance.metadata.deployed-by=jenkins

spring:
  boot:
    admin:
      client:
        instance:
          metadata:
            environment: production
            team: backend
            region: us-east-1
            version: 1.2.3
            deployed-by: jenkins
            custom-tag: custom-value

@Component
@Profile("production")
public class ProductionMetadataContributor implements MetadataContributor {
    
    @Override
    public Map<String, String> getMetadata() {
        Map<String, String> metadata = new HashMap<>();
        metadata.put("environment", "production");
        metadata.put("monitoring.level", "enhanced");
        return metadata;
    }
}

@Component
@ConditionalOnProperty(value = "app.metadata.kubernetes.enabled", havingValue = "true")
public class KubernetesMetadataContributor implements MetadataContributor {
    
    @Override
    public Map<String, String> getMetadata() {
        Map<String, String> metadata = new HashMap<>();
        
        // Read from Kubernetes downward API
        metadata.put("k8s.namespace", System.getenv("POD_NAMESPACE"));
        metadata.put("k8s.pod.name", System.getenv("POD_NAME"));
        metadata.put("k8s.node.name", System.getenv("NODE_NAME"));
        
        return metadata;
    }
}

@Component
@Scheduled(fixedRate = 60000) // Update every minute
public class DynamicMetadataService {
    
    private final ApplicationRegistrator registrator;
    
    public DynamicMetadataService(ApplicationRegistrator registrator) {
        this.registrator = registrator;
    }
    
    @Scheduled(fixedRate = 300000) // Re-register every 5 minutes with updated metadata
    public void updateMetadata() {
        // This will trigger re-registration with current metadata
        registrator.register();
    }
}