fix(auto-instrumentation-node): resource detector from env should be the last detector (#3363)

Author: maryliag

packages/auto-instrumentations-node/README.md

@@ -50,7 +50,7 @@ export OTEL_EXPORTER_OTLP_TRACES_ENDPOINT="https://your-endpoint"
 export OTEL_EXPORTER_OTLP_HEADERS="x-api-key=your-api-key"
 export OTEL_EXPORTER_OTLP_TRACES_HEADERS="x-api-key=your-api-key"
 export OTEL_RESOURCE_ATTRIBUTES="service.namespace=my-namespace"
-export OTEL_NODE_RESOURCE_DETECTORS="env,host,os,serviceinstance"
+export OTEL_NODE_RESOURCE_DETECTORS="host,os,serviceinstance,env"
 export OTEL_SERVICE_NAME="client"
 export NODE_OPTIONS="--require @opentelemetry/auto-instrumentations-node/register"
 node app.js
@@ -74,9 +74,15 @@ By default, all SDK resource detectors are used, but you can use the environment
 For example, to enable only the `env`, `host` detectors:
 
 ```shell
-export OTEL_NODE_RESOURCE_DETECTORS="env,host"
+export OTEL_NODE_RESOURCE_DETECTORS="host,env"
 ```
 
+NOTE: The order set on `OTEL_NODE_RESOURCE_DETECTORS` will be respected and the detectors will be executed in order.
+For example, if you have `OTEL_RESOURCE_ATTRIBUTES="service.instance.id=custom-name"`, but also `serviceinstance` and `env` on `OTEL_NODE_RESOURCE_DETECTORS`, it can have 2 scenarios:
+
+- `OTEL_NODE_RESOURCE_DETECTORS="serviceinstance,env"` will have the `service.instance.id` as `custom-name`
+- `OTEL_NODE_RESOURCE_DETECTORS="env,serviceinstance"` will have the `service.instance.id` as a random UUID
+
 By default, all [Supported Instrumentations](#supported-instrumentations) are enabled, unless they are annotated with "default disabled".
 You can use the environment variable `OTEL_NODE_ENABLED_INSTRUMENTATIONS` to enable only certain instrumentations, including "default disabled" ones
 OR the environment variable `OTEL_NODE_DISABLED_INSTRUMENTATIONS` to disable only certain instrumentations,

packages/auto-instrumentations-node/src/utils.ts

@@ -298,7 +298,6 @@ export function getResourceDetectorsFromEnv(): Array<ResourceDetector> {
     ResourceDetector | ResourceDetector[]
   >([
     [RESOURCE_DETECTOR_CONTAINER, containerDetector],
-    [RESOURCE_DETECTOR_ENVIRONMENT, envDetector],
     [RESOURCE_DETECTOR_HOST, hostDetector],
     [RESOURCE_DETECTOR_OS, osDetector],
     [RESOURCE_DETECTOR_SERVICE_INSTANCE_ID, serviceInstanceIdDetector],
@@ -319,6 +318,7 @@ export function getResourceDetectorsFromEnv(): Array<ResourceDetector> {
       RESOURCE_DETECTOR_AZURE,
       [azureAppServiceDetector, azureFunctionsDetector, azureVmDetector],
     ],
+    [RESOURCE_DETECTOR_ENVIRONMENT, envDetector],
   ]);
 
   const resourceDetectorsFromEnv =