Fix SDK already exists detection. (#1284)

Bootstrap/Helpers.ts

@@ -1,34 +1,46 @@
 import { DiagnosticLog, DiagnosticMessageId } from "./DataModel";
 import { DiagnosticLogger } from "./DiagnosticLogger";
 
+const USER_APP_PATH = "/home/site/wwwroot";
+
 export function sdkAlreadyExists(_logger: DiagnosticLogger): boolean {
     try {
         // appInstance should either resolve to user SDK or crash. If it resolves to attach SDK, user probably modified their NODE_PATH
         let appInstance: string;
         try {
             // Node 8.9+
-            appInstance = (require.resolve as any)("applicationinsights", { paths: [process.cwd()] });
+            // If we find the applicationinsights module under in the user application path, do not attach the SDK
+            // In order for this to work in Windows, we need to pass the full "/home/site/wwwroot" path to require.resolve
+            appInstance = (require.resolve as any)("applicationinsights", { paths: [USER_APP_PATH] });
+            if (appInstance) {
+                diagnosticLogSdkExists(_logger, appInstance);
+                return true;
+            }
         } catch (e) {
             // Node <8.9
             appInstance = require.resolve(process.cwd() + "/node_modules/applicationinsights");
-        }
-        // If loaded instance is in Azure machine home path do not attach the SDK, this means customer already instrumented their app
-        if (appInstance.indexOf("home") > -1) {
-            const diagnosticLog: DiagnosticLog = {
-                message: "Application Insights SDK already exists. Module is already installed in this application; not re-attaching. Installed SDK location: " + appInstance,
-                properties: {
-                    "msgId": DiagnosticMessageId.sdkExists
-                }
-            };
-            _logger.logError(diagnosticLog);
-            return true;
-        }
-        else {
-            // ApplicationInsights could be loaded outside of customer application, attach in this case
-            return false;
+            // If loaded instance is in Azure machine home path do not attach the SDK, this means customer already instrumented their app
+            if (appInstance.indexOf("home") > -1) {
+                diagnosticLogSdkExists(_logger, appInstance);
+                return true;
+            }
+            else {
+                // ApplicationInsights could be loaded outside of customer application, attach in this case
+                return false;
+            }
         }
     } catch (e) {
         // crashed while trying to resolve "applicationinsights", so SDK does not exist. Attach appinsights
         return false;
     }
 }
+
+function diagnosticLogSdkExists(logger: DiagnosticLogger, appInstance: string): void {
+    const diagnosticLog: DiagnosticLog = {
+        message: "Application Insights SDK already exists. Module is already installed in this application; not re-attaching. Installed SDK location: " + appInstance,
+        properties: {
+            "msgId": DiagnosticMessageId.sdkExists
+        }
+    };
+    logger.logError(diagnosticLog);
+}