Application Startup

The usual startup flow is:

import 'reflect-metadata';

import Kernel from '@haskou/ddd-kernel';
import { ExpressKernelServer } from '@haskou/ddd-kernel/adapters/ui/express';
import { applicationConsumers } from './apps/ApplicationConsumers.js';
import { recurringSchedulers } from './apps/ApplicationSchedulers.js';
import GetUserByIdRoute from './apps/api/routes/GetUserByIdRoute.js';

const environmentSchema = {
  NODE_ENV: { defaultValue: 'local', type: 'string' },
  PORT: { defaultValue: 3000, type: 'number' },
} as const;

const kernel = new Kernel({
  environmentSchema,
  sourceDirectory: 'src',
  servicesYamlPath: 'config/container/services.yaml',
});

kernel.loadEnvironmentVariables();

await kernel.dependencyInjection({
  containerBuild: kernel.environment.NODE_ENV !== 'production',
});
kernel.registerRoutes(GetUserByIdRoute);
kernel.registerConsumers(...applicationConsumers);
kernel.registerSchedulers(...recurringSchedulers);

const server = new ExpressKernelServer({
  kernel,
  port: kernel.environment.PORT,
});
kernel.registerShutdownHook(() => server.close());

await server.run();
await kernel.runConsumers();
await kernel.runSchedulers();

kernel.logger.info(`Application running on port ${kernel.environment.PORT}`);

loadEnvironmentVariables() loads .env.local by default when NODE_ENV is not set. Passing test loads .env.test; passing an empty string loads .env. When a schema is configured, required variables are validated and values are parsed before they are exposed through kernel.environment.

containerBuild: true regenerates config/container/services.yaml. Production runtimes should usually load the generated YAML instead of rebuilding from src.

new Kernel(...) configures defaults for the runtime. kernel.dependencyInjection(...) can override the DI-specific values for a particular boot.

Call kernel.shutdown() from your process signal handlers to stop consumers, stop schedulers, close servers, flush logs and release connections registered through shutdown hooks:

process.once('SIGTERM', () => {
  void kernel.shutdown();
});