Adjusting the logic to determine the warmup call in placeholder simulation mode to align with the prod (#10918)

* Placeholder simulation mode should trigger warmup code path using /api/warmup call to execute the Invocation middleware flow.

* Add release notes.

Author: kshyju

eng/ci/templates/official/jobs/run-coldstart.yml

@@ -124,7 +124,7 @@ jobs:
       displayName: Start host in placeholder mode
 
   - pwsh: |     
-      $url = "http://localhost:5000" # In placeholder simulation mode, calling homepage triggers warmup.
+      $url = "http://localhost:5000/api/warmup?restart=1"
       Write-Host "Checking if host is ready at $url..."
       $maxAttempts = 10
 

release_notes.md

@@ -8,3 +8,4 @@
 - Add support for new FeatureFlag `EnableAzureMonitorTimeIsoFormat` to enable iso time format for azmon logs for Linux Dedicated/EP Skus. (#10684)
 - Allow sync trigger to happen in managed environment when `AzureWebJobsStorage` is not set (#10767)
 - Fixing default DateTime bug with TimeZones in TimerTrigger (#10906)
+- Adjusting the logic to determine the warmup call in placeholder simulation mode to align with the production flow (#10918)

src/WebJobs.Script.WebHost/Middleware/HostWarmupMiddleware.cs

@@ -167,9 +167,9 @@ public async Task HostWarmupAsync(HttpRequest request)
 
         public static bool IsWarmUpRequest(HttpRequest request, bool inStandbyMode, IEnvironment environment)
         {
-            // In placeholder simulation mode, we want the homepage request to also trigger warmup code.
-            var isWarmupViaHomePageRequest = Utility.IsInPlaceholderSimulationMode && inStandbyMode && request.Path.Value == "/";
-            if (isWarmupViaHomePageRequest)
+            // Check if the request is a warmup request in placeholder simulation mode
+            if (Utility.IsInPlaceholderSimulationMode && inStandbyMode &&
+                (request.Path.StartsWithSegments(_warmupRoutePath, StringComparison.OrdinalIgnoreCase) || request.Path.StartsWithSegments(_warmupRouteAlternatePath, StringComparison.OrdinalIgnoreCase)))
             {
                 return true;
             }