> ## Documentation Index
> Fetch the complete documentation index at: https://docs.appsignal.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Node.js Core

<Note>
  Default instrumentations can be disabled via the `disableDefaultInstrumentations` config option. You can read more about how to configure this in our [Configuration Options documentation](/nodejs/3.x/configuration/options#option-disabledefaultinstrumentations).
</Note>

Node.js contains several internal modules designed to enable asynchronous I/O capable APIs for your application. AppSignal provides automatic instrumentation for many of these modules.

## `http` and `https` instrumentation

AppSignal for Node.js will auto-instrument any incoming and outgoing HTTP(S) requests. Incoming requests will appear as the root span of a trace, while outgoing requests will appear as child spans of an incoming request root span.

For incoming requests to be instrumented in detail, you must use a supported web framework such as [Express](/nodejs/3.x/integrations/express), [Koa.js](/nodejs/3.x/integrations/koajs) or [NestJS](/nodejs/3.x/integrations/nestjs).

## Heap statistics minutely probe

By default, Appsignal for Node.js will register a minutely probe that keeps track of the V8 engine's heap statistics. Once we detect these metrics we'll add a [magic dashboard](https://blog.appsignal.com/2019/03/27/magic-dashboards.html) to your app.

The metrics reported by this method correspond to those reported by the `v8.getHeapStatistics` method in the Node.js standard library. For more details on how to interpret these metrics, [see the official Node.js documentation on the `v8` module](https://nodejs.org/api/v8.html#v8getheapstatistics). The probe will report the following metrics grouped by `hostname` tag:

* `nodejs_total_heap_size` - gauge
* `nodejs_total_heap_size_executable` - gauge
* `nodejs_total_physical_size` - gauge
* `nodejs_used_heap_size` - gauge
* `nodejs_malloced_memory` - gauge
* `nodejs_number_of_native_contexts` - gauge
* `nodejs_number_of_detached_contexts` - gauge