feat: add OpenTelemetry tracing setup with Azure Monitor

Author: sinedied

package-lock.json

@@ -3,7 +3,7 @@
   "version": "1.0.0",
   "description": "Azure Functions API for Contoso Burgers",
   "private": true,
-  "main": "./dist/src/functions/*.js",
+  "main": "./dist/src/{tracing.js,functions/*.js}",
   "scripts": {
     "build": "tsc",
     "watch": "tsc -w",
@@ -21,6 +21,7 @@
     "@azure/cosmos": "^4.3.0",
     "@azure/functions": "^4.7.0",
     "@azure/identity": "^4.8.0",
+    "@azure/monitor-opentelemetry": "^1.14.0",
     "@azure/storage-blob": "^12.27.0",
     "js-yaml": "^4.1.0"
   },

packages/burger-api/package.json

@@ -0,0 +1,18 @@
+// OpenTelemetry tracing setup
+// This file is loaded automatically by the Azure Functions host,
+// as configured in package.json "main" field.
+
+import { useAzureMonitor } from "@azure/monitor-opentelemetry";
+
+let isTracingInitialized = false;
+if (!isTracingInitialized) {
+  // Initialize tracing and export to Azure Monitor
+  const appInsightsConnectionString = process.env["APPLICATIONINSIGHTS_CONNECTION_STRING"];
+  if (appInsightsConnectionString) {
+    useAzureMonitor({
+      azureMonitorExporterOptions: { connectionString: appInsightsConnectionString }
+    });
+  }
+
+  isTracingInitialized = true;
+}