configuring-runtime-dependencies

Purpose

Framework configuration and runtime wiring of the different components of the application.

Guidelines

DO:

• Use constructor-based injection everywhere - no field injection, no setter injection
• Use separate configuration classes with programmatic wiring for complex dependencies or when auto-wiring is not enough
• Group related bean definitions in dedicated configuration classes (e.g., KafkaConfig, HttpClientConfig)
• Keep configuration classes in the infrastructure layer
• Use default parameter values in constructors for optional dependencies (e.g., generateId: () -> UUID = { UUID.randomUUID() })

DON'T:

• Put configuration classes in domain or application layers - they belong in the infrastructure layer
• Create circular dependencies between beans

Spring specifics

• @Configuration classes declare @Bean methods to create and wire infrastructure components
• @ConfigurationProperties(prefix = "...") binds YAML/properties to a data class
• Don't use @Autowired annotation. Use constructor-based injection instead
• Use spring starter modules to avoid manual configuration of common dependencies (e.g., spring-boot-starter-web, spring-boot-starter-data-jdbc, spring-boot-starter-kafka)
• Use @Value for simple configurations - use @ConfigurationProperties for complex configurations with multiple related properties

Examples

Please use always these examples as reference: examples.md