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Async Providers ​

Problem ​

Implement async providers in a production-friendly way with @vielzeug/wireit while keeping setup and cleanup explicit.

Runnable Example ​

The snippet below is copy-paste runnable in a TypeScript project with @vielzeug/wireit installed.

Database connection ​

ts
const DbToken = createToken<IDatabase>('Database');

container.factory(
  DbToken,
  async (config) => {
    const db = new PostgresClient({ connectionString: config.dbUrl });
    await db.connect();
    return db;
  },
  {
    deps: [ConfigToken],
    lifetime: 'singleton',
    dispose: (db) => db.end(),
  },
);

// Must use getAsync for async providers
const db = await container.getAsync(DbToken);

await using (AsyncDisposable) ​

ts
async function bootstrap() {
  await using container = createContainer();

  container.factory(
    DbToken,
    async () => {
      const db = new Database(env.DB_URL);
      await db.connect();
      return db;
    },
    { dispose: (db) => db.close() },
  );

  const app = container.get(AppToken);
  await app.start();
  // container.dispose() is called automatically when bootstrap() exits
}

Expected Output ​

  • The example runs without type errors in a standard TypeScript setup.
  • The main flow produces the behavior described in the recipe title.

Common Pitfalls ​

  • Forgetting cleanup/dispose calls can leak listeners or stale state.
  • Skipping explicit typing can hide integration issues until runtime.
  • Not handling error branches makes examples harder to adapt safely.