stack/apps/api/src/main.ts

import { NestFactory } from "@nestjs/core";
import { ValidationPipe } from "@nestjs/common";
import { AppModule } from "./app.module";
import { GlobalExceptionFilter } from "./filters/global-exception.filter";

function getPort(): number {
  const portEnv = process.env.PORT;

  if (portEnv === undefined || portEnv === "") {
    return 3001;
  }

  const port = parseInt(portEnv, 10);

  if (isNaN(port)) {
    throw new Error(`Invalid PORT environment variable: "${portEnv}". PORT must be a number.`);
  }

  if (port < 1 || port > 65535) {
    throw new Error(
      `Invalid PORT environment variable: ${String(port)}. PORT must be between 1 and 65535.`
    );
  }

  return port;
}

async function bootstrap() {
  const app = await NestFactory.create(AppModule);

  // Enable global validation pipe with transformation
  app.useGlobalPipes(
    new ValidationPipe({
      transform: true,
      whitelist: true,
      forbidNonWhitelisted: false,
      transformOptions: {
        enableImplicitConversion: false,
      },
    })
  );

  app.useGlobalFilters(new GlobalExceptionFilter());
  app.enableCors();

  const port = getPort();
  await app.listen(port);

  console.log(`API running on http://localhost:${String(port)}`);
}

bootstrap().catch((err: unknown) => {
  const isProduction = process.env.NODE_ENV === "production";
  const errorMessage = err instanceof Error ? err.message : String(err);
  const errorStack = err instanceof Error ? err.stack : undefined;

  if (isProduction) {
    console.error(
      JSON.stringify({
        level: "error",
        message: "Failed to start application",
        error: errorMessage,
        timestamp: new Date().toISOString(),
      })
    );
  } else {
    console.error("Failed to start application:", errorMessage);
    if (errorStack) {
      console.error(errorStack);
    }
  }

  process.exit(1);
});