Spring Profiles & Configuration

Quick Start

@Configuration
@Profile("dev")
public class DevConfig {
    @Bean
    public DataSource dataSource() {
        return new EmbeddedDatabaseBuilder()
            .setType(EmbeddedDatabaseType.H2)
            .build();
    }
}

@Configuration
@Profile("prod")
public class ProdConfig {
    @Bean
    public DataSource dataSource() {
        HikariDataSource ds = new HikariDataSource();
        ds.setJdbcUrl(System.getenv("DATABASE_URL"));
        return ds;
    }
}

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Profile Activation

# 1. application.yml
spring:
  profiles:
    active: dev

# 2. Environment variable: SPRING_PROFILES_ACTIVE=prod
# 3. Command line: java -jar app.jar --spring.profiles.active=prod
# 4. JVM property: java -Dspring.profiles.active=prod -jar app.jar

Profile Groups

spring:
  profiles:
    active: production
    group:
      production:
        - prod
        - prod-db
        - prod-security
      development:
        - dev
        - dev-db
        - dev-tools

Profile Expression

@Profile("cloud & kubernetes")  // AND
@Profile("dev | test")          // OR
@Profile("!prod")               // NOT
@Profile("(dev | test) & !integration")  // Combined

---

@ConfigurationProperties

@ConfigurationProperties(prefix = "app")
@Validated
public class AppProperties {

    @NotBlank
    private String name;

    @NotNull
    private String version;

    private final Security security = new Security();

    @Validated
    public static class Security {
        @NotBlank
        private String jwtSecret;

        @Min(3600)
        private long jwtExpiration = 86400;

        @NotEmpty
        private List<String> allowedOrigins = new ArrayList<>();
    }

    // Getters and setters
}

// Abilitazione
@Configuration
@EnableConfigurationProperties(AppProperties.class)
public class AppConfig {}

app:
  name: MyApplication
  version: 1.0.0
  security:
    jwt-secret: ${JWT_SECRET}
    jwt-expiration: 86400
    allowed-origins:
      - https://example.com

Immutable Configuration (Record)

@ConfigurationProperties(prefix = "app.mail")
public record MailProperties(
    @NotBlank String host,
    @Min(1) @Max(65535) int port,
    String username,
    @DefaultValue("false") boolean starttls
) {}

Full Reference: See properties.md for Property Sources, External Configuration (Config Server, K8s, Vault).

---

Conditional Beans

@Bean
@ConditionalOnProperty(name = "feature.email.enabled", havingValue = "true")
public EmailService emailService() {
    return new RealEmailService();
}

@Bean
@Profile("dev")
public CacheManager devCacheManager() {
    return new ConcurrentMapCacheManager();
}

@Bean
@ConditionalOnMissingBean(UserService.class)
public UserService defaultUserService() {
    return new DefaultUserService();
}

Full Reference: See conditional.md for Custom Conditions, Validation, Testing.

---

Secrets Management

spring:
  datasource:
    password: ${DB_PASSWORD}

app:
  security:
    jwt-secret: ${JWT_SECRET}

Full Reference: See secrets.md for Jasypt Encryption, Vault Integration.

---

Best Practices

Do	Don't
Use @ConfigurationProperties for structured config	Use @Value for complex config
Validate properties with Bean Validation	Skip validation
Use profile groups for complex environments	Duplicate configuration
Externalize all secrets	Commit secrets to repository
Use sensible default values	Require all properties

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Production Checklist

• Secrets externalized (env vars, Vault)
• Profiles configured for each environment
• Validation enabled on all properties
• Default values for optional properties
• Profile groups for related config
• Configuration encrypted where needed

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When NOT to Use This Skill

• Runtime feature flags - Consider LaunchDarkly, Flipt
• Centralized config - Use spring-cloud-config skill
• Secrets only - Consider HashiCorp Vault directly

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Anti-Patterns

Anti-Pattern	Problem	Solution
Secrets in git	Security vulnerability	Use env vars or secrets manager
Wrong prefix	Properties not loaded	Verify prefix matches YAML
Missing @Validated	Validation ignored	Add @Validated annotation
@Value for complex config	Unmaintainable	Use @ConfigurationProperties

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Quick Troubleshooting

Problem	Diagnostic	Fix
Properties not loaded	Check prefix	Verify @ConfigurationProperties prefix
Profile not active	Check logs at startup	Set spring.profiles.active
Binding failed	Check type	Use correct types (Duration, etc.)
Env var not resolved	Check naming	Use UPPER_SNAKE_CASE

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Reference Files

File	Content
properties.md	Property Sources, External Configuration
conditional.md	Conditional Beans, Validation, Testing
secrets.md	Secrets Management, Encryption

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External Documentation

• Externalized Configuration
• Profiles