kora-di-runtime

Kora DI Runtime — Runtime Injection Behavior

Kora sub-skill — obey the kora-v1 meta rules on every task: R0 ensure .kora-agent/ docs+examples are cloned · R1 read this sub-skill before writing code · R2 Kora APIs only — no Spring/Micronaut/Quarkus, no invented annotations or config keys · R3 journal any incorrect Kora usage. Add comments/Javadoc only if asked.

Kora Version: 1.x
Focus: Runtime DI — lifecycle, tags, collections, lazy dependencies, interception.

Read this first when:

• Marking components as @Root for automatic startup
• Implementing Lifecycle for init/release logic
• Disambiguating with @Tag, collecting with All<T>
• Using ValueOf<T> for lazy dependencies
• Wrapping components with GraphInterceptor

References: See references/ for detailed guides on each topic.

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Quick Start

@Root — Self-Starting Components

Only components that are dependencies of other components, or marked @Root (ru.tinkoff.kora.common.annotation.Root), are instantiated at runtime. @Root goes on a @Component class or on a @KoraApp/@Module factory method.

When to use @Root: HTTP/gRPC servers, Kafka consumers, cache warmers, schedulers, startup tasks — anything that must run even though nothing depends on it.

A self-starting worker:

import ru.tinkoff.kora.application.graph.Lifecycle;
import ru.tinkoff.kora.common.Component;
import ru.tinkoff.kora.common.annotation.Root;

@Root
@Component
public final class ServerRunner implements Lifecycle {
    private final ServerConfig config; // a @ConfigSource interface, injected as a component

    public ServerRunner(ServerConfig config) {
        this.config = config;
    }

    @Override
    public void init() throws Exception {
        System.out.println("Starting server on port " + config.port());
        // Bind socket, start accepting traffic
    }

    @Override
    public void release() throws Exception {
        System.out.println("Stopping server");
        // Stop server, release connections
    }
}