GitBook: [#159] add NestJS instructions

Author: OrGeva10

SUMMARY.md

@@ -13,8 +13,9 @@
 * [How Do You Want to Send Your Data?](send-tracing-data-to-aspecto/send-tracing-data-to-aspecto.md)
 * [Using Aspecto SDK](send-tracing-data-to-aspecto/aspecto-sdk/README.md)
   * [NodeJS](send-tracing-data-to-aspecto/aspecto-sdk/nodejs/README.md)
-    * [For AWS Lambda](send-tracing-data-to-aspecto/aspecto-sdk/nodejs/lambda.md)
-    * [For GCF](send-tracing-data-to-aspecto/aspecto-sdk/nodejs/gcf.md)
+    * [NestJS](send-tracing-data-to-aspecto/aspecto-sdk/nodejs/nestjs.md)
+    * [AWS Lambda](send-tracing-data-to-aspecto/aspecto-sdk/nodejs/lambda.md)
+    * [Google Cloud Functions](send-tracing-data-to-aspecto/aspecto-sdk/nodejs/gcf.md)
     * [Customize Defaults](send-tracing-data-to-aspecto/aspecto-sdk/nodejs/customize-defaults/README.md)
       * [Advanced](send-tracing-data-to-aspecto/aspecto-sdk/nodejs/customize-defaults/advanced.md)
       * [Send Spans Manually](send-tracing-data-to-aspecto/aspecto-sdk/nodejs/customize-defaults/manual-spans.md)

send-tracing-data-to-aspecto/aspecto-sdk/nodejs/nestjs.md

@@ -0,0 +1,52 @@
+---
+description: Instrument your NestJS application using Aspecto
+---
+
+# NestJS
+
+## Auto Instrument
+
+Nest applications are commonly started in one of 2 ways:
+
+* Nest cli (`nest start`)
+* Directly with the `node` executable (for example: `node dist/main`)
+
+It is recommended to use ["Auto Instrument" technique](./#auto-instrument) with node's "preload" command line option, to ensure instrumentation is initialized before Nest framework.
+
+### Using Nest Cli
+
+To instrument your Nest application when started with Nest cli, add the ["-e" ("--exec")](https://docs.nestjs.com/cli/usages#nest-start) option to `nest start` like this:
+
+```
+nest start -e 'node -r @aspecto/opentelemetry/auto-instrument'
+```
+
+This should be added everywhere `nest start` is invoked (`package.json`, scripts, terminal, etc).
+
+### Using Node Executable
+
+To instrument you Nest application when started with node executable, add the ["-r" ("--require")](https://nodejs.org/api/cli.html#-r---require-module) to `node` execution like this:
+
+```
+node -r '@aspecto/opentelemetry/auto-instrument' dist/main
+```
+
+## Configuration
+
+When instrumenting an application with "Auto Instrument", configuration is supplied via environment variables or `aspecto.json` file. 
+
+{% hint style="info" %}
+`ASPECTO_AUTH` **must be provided.** [Other configuration options](customize-defaults/advanced.md) are optional.
+{% endhint %}
+
+### .env File
+
+This part is relevant if you are using `@nestjs/config` package to load environment variables from `.env` file (or if you are loading the file yourself).
+
+If you store Aspecto's SDK config options in `.env` file, it needs to be preloaded before `@aspecto/opentelemetry`, e.g.
+
+```
+nest start -e 'node -r dotenv/config -r @aspecto/opentelemetry/auto-instrument'
+// or
+node -r dotenv/config -r '@aspecto/opentelemetry/auto-instrument' dist/main
+```