Fixing an issue leading to a race when proxying HTTP requests to the worker. (#10121)

Author: fabiocav

release_notes.md

@@ -12,4 +12,5 @@
 - Update Node.js Worker Version to [3.10.0](https://github.com/Azure/azure-functions-nodejs-worker/releases/tag/v3.10.0) (#9999)
 - Update PowerShell worker 7.2 to [4.0.3220](https://github.com/Azure/azure-functions-powershell-worker/releases/tag/v4.0.3220)
 - Update PowerShell worker 7.4 to [4.0.3219](https://github.com/Azure/azure-functions-powershell-worker/releases/tag/v4.0.3219)
-- Ensuring proxies are disabled, with a warning, when running in Flex Consumption. 
+- Ensuring proxies are disabled, with a warning, when running in Flex Consumption. 
+- Fixed an issue leading to a race when invocation responses returned prior to HTTP requests being sent in proxied scenarios.

src/WebJobs.Script.Grpc/Channel/GrpcWorkerChannel.cs

@@ -890,6 +890,14 @@ internal async Task SendInvocationRequest(ScriptInvocationContext context)
                 _executingInvocations.TryAdd(invocationRequest.InvocationId, new(context, _messageDispatcherFactory.Create(invocationRequest.InvocationId)));
                 _metricsLogger.LogEvent(string.Format(MetricEventNames.WorkerInvoked, Id), functionName: Sanitizer.Sanitize(context.FunctionMetadata.Name));
 
+                // If the worker supports HTTP proxying, ensure this request is forwarded prior
+                // to sending the invocation request to the worker, as this will ensure the context
+                // is properly set up.
+                if (IsHttpProxyingWorker && context.FunctionMetadata.IsHttpTriggerFunction())
+                {
+                    _httpProxyService.StartForwarding(context, _httpProxyEndpoint);
+                }
+
                 await SendStreamingMessageAsync(new StreamingMessage
                 {
                     InvocationRequest = invocationRequest
@@ -900,11 +908,6 @@ await SendStreamingMessageAsync(new StreamingMessage
                     var cancellationCtr = context.CancellationToken.Register(() => SendInvocationCancel(invocationRequest.InvocationId));
                     context.Properties.Add(ScriptConstants.CancellationTokenRegistration, cancellationCtr);
                 }
-
-                if (IsHttpProxyingWorker && context.FunctionMetadata.IsHttpTriggerFunction())
-                {
-                    _ = _httpProxyService.ForwardAsync(context, _httpProxyEndpoint);
-                }
             }
             catch (Exception invokeEx)
             {

src/WebJobs.Script.Grpc/Server/DefaultHttpProxyService.cs

@@ -66,7 +66,7 @@ public async Task EnsureSuccessfulForwardingAsync(ScriptInvocationContext contex
             }
         }
 
-        public Task ForwardAsync(ScriptInvocationContext context, Uri httpUri)
+        public void StartForwarding(ScriptInvocationContext context, Uri httpUri)
         {
             ArgumentNullException.ThrowIfNull(context);
 
@@ -89,8 +89,6 @@ public Task ForwardAsync(ScriptInvocationContext context, Uri httpUri)
 
             var forwardingTask = _httpForwarder.SendAsync(httpContext, httpUri.ToString(), _messageInvoker, _forwarderRequestConfig).AsTask();
             context.Properties.Add(ScriptConstants.HttpProxyTask, forwardingTask);
-
-            return forwardingTask;
         }
     }
 }

src/WebJobs.Script.Grpc/Server/IHttpProxyService.cs

@@ -11,6 +11,11 @@ public interface IHttpProxyService
     {
         Task EnsureSuccessfulForwardingAsync(ScriptInvocationContext context);
 
-        Task ForwardAsync(ScriptInvocationContext context, Uri httpUri);
+        /// <summary>
+        /// Initiates a request forward and updates the current context to track forwarding operation.
+        /// </summary>
+        /// <param name="context">The <see cref="ScriptInvocationContext"/> for the HTTP invocation.</param>
+        /// <param name="httpUri">The target URI used for forwarding.</param>
+        void StartForwarding(ScriptInvocationContext context, Uri httpUri);
     }
 }