Configuration & Profiles

Konfiguration & Profile

Spring Boot macht Konfiguration extern, type-safe und umgebungsspezifisch.

Lektion 41: application.yml & @ConfigurationProperties

app:
  name: "Demo API"
  max-connections: 100
  timeout: 30s
  features:
    - audit
    - metrics

@ConfigurationProperties(prefix = "app")
public record AppProperties(
    String name,
    int maxConnections,
    Duration timeout,
    List<String> features
) {}

Type-safe, validated, documented. Kein @Value-String-Parsing.

Lektion 42: Profile

# application-dev.yml
app:
  max-connections: 10

# application-prod.yml
app:
  max-connections: 200

java -jar app.jar --spring.profiles.active=prod

Lektion 43: Externe Konfiguration

Quellen (Priorität absteigend):

1. Kommandozeilenargumente
2. Umgebungsvariablen (APP_NAME=...)
3. application-{profile}.yml
4. application.yml
5. Standardwerte im Code

Lektion 44: Type-safe Configuration

@Bean
CommandLineRunner demo(AppProperties props) {
    return args -> {
        System.out.println("Name: " + props.name());
        System.out.println("Timeout: " + props.timeout());
        props.features().forEach(f -> System.out.println("Feature: " + f));
    };
}

Lektion 45: Config-Validierung

@ConfigurationProperties(prefix = "app")
@Validated
public record AppProperties(
    @NotBlank String name,
    @Min(1) @Max(1000) int maxConnections,
    @NotNull Duration timeout,
    List<String> features
) {}

Spring prüft beim Start: fehlt app.name oder ist maxConnections > 1000, startet die App gar nicht — Fail-fast.