Function underPressureKoaMiddleware

underPressureKoaMiddleware(
__namedParameters: Readonly<Partial<MiddlewareOptions>>,
): (ctx: Context, next: Next) => Promise<void>
Creates a Koa middleware that monitors system metrics and responds with a 503 Service Unavailable status when the system is under pressure, as determined by the provided options and current metrics.
Parameters
- __namedParameters: Readonly<Partial<MiddlewareOptions>>
Returns (ctx: Context, next: Next) => Promise<void>
A Koa middleware function that checks system pressure and responds accordingly.
Remarks
When the system is detected to be under pressure, the middleware:
- Notifies observers with the current metrics.
- Sets the Retry-After header.
- Responds with HTTP 503 Service Unavailable.
- Ends the response. Otherwise, it passes control to the next middleware.
Example
```
app.use(underPressureKoaMiddleware({
  sampleIntervalInMs: 1000,
  resolution: 10,
  webServerMetricsPort: 9090,
  maxEventLoopDelay: 1000,
  maxEventLoopUtilization: 0.9
}));
```
- Defined in library/middleware/koa-under-pressure.ts:39