---
title: "Elysia"
description: "Derive auditLog on the request context with global plugin scope and optional waitUntil."
---

> Documentation Index
> Fetch the complete documentation index at: https://logbun-docs.abshahin.workers.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Elysia

```sh
npm install elysia
pnpm add elysia
yarn add elysia
bun add elysia
```

```ts
import { Elysia } from 'elysia';
import { AuditLogger } from 'logbun';
import { auditPlugin } from 'logbun/plugins/elysia';
import type { IAdapter } from 'logbun';

type Actions = 'course.created' | 'course.deleted';

declare const adapter: IAdapter;
declare function tenantIdFromVerifiedSession(ctx: unknown): string | undefined;

const audit = new AuditLogger<Actions>({
  namespace: 'api',
  adapter,
  requireTenantId: true,
});
await audit.ready;

const app = new Elysia()
  .use(
auditPlugin(audit, {
  trustedProxyCount: 1,
  getTenantId: (ctx) => tenantIdFromVerifiedSession(ctx),
  // Workers: Elysia does not inject ExecutionContext.
  // getWaitUntil: () => (task) => executionCtx.waitUntil(task),
}),
  )
  .post('/courses', async ({ auditLog, body }) => {
auditLog.fire('course.created', {
  actorId: 'user_1',
  entityId: 'course_1',
});
await auditLog.fireAsync('course.created', {
  actorId: 'user_1',
  entityId: 'course_1',
});
  });
```

The plugin is registered as `{ name: 'logbun' }` with `.derive({ as: 'global' })`, so a parent `app.use(auditPlugin(...))` sees `auditLog` on the request context. Local (non-global) derive would stay isolated to the plugin instance.

`getTenantId` receives the **full** Elysia derive context (same `ctx` as `getWaitUntil`), not `{ request }` only.

`extractWaitUntil` is also exported from `logbun/plugins/elysia`. It reads `executionCtx` / `executionContext` / `ctx` / `store` / a request-scoped `waitUntil` already on the derive context. It does not import `cloudflare:workers`. On Workers, pass `getWaitUntil`.

Options:

```ts
{
  trustedProxyCount?: number; // default 0
  getTenantId?: (ctx: unknown) => string | undefined;
  getWaitUntil?: (ctx: unknown) => ((task: Promise<unknown>) => void) | undefined;
}
```

Source: https://logbun-docs.abshahin.workers.dev/guides/elysia/index.mdx