feat: Parse Azure Function HttpTrigger parameters (#2776)

Author: tippmar-nr

src/Agent/NewRelic/Agent/Core/Transactions/NoOpTransaction.cs

@@ -23,6 +23,7 @@ public class NoOpTransaction : ITransaction, ITransactionExperimental
         public bool IsValid => false;
         public bool IsFinished => false;
         public ISegment CurrentSegment => Segment.NoOpSegment;
+        public bool HasHttpResponseStatusCode => false;
 
         public DateTime StartTime => DateTime.UtcNow;
 

src/Agent/NewRelic/Agent/Core/Transactions/Transaction.cs

@@ -72,6 +72,8 @@ public ISegment CurrentSegment
             }
         }
 
+        public bool HasHttpResponseStatusCode => TransactionMetadata.HttpResponseStatusCode.HasValue;
+
         public ITracingState TracingState { get; private set; }
 
         public string TraceId

src/Agent/NewRelic/Agent/Extensions/NewRelic.Agent.Extensions/Api/ITransaction.cs

@@ -33,6 +33,8 @@ public interface ITransaction
         /// </summary>
         ISegment CurrentSegment { get; }
 
+        bool HasHttpResponseStatusCode { get; }
+
         /// <summary>
         /// End this transaction.
         /// </summary>

src/Agent/NewRelic/Agent/Extensions/Providers/Wrapper/AzureFunction/FunctionsHttpProxyingMiddlewareWrapper.cs

@@ -0,0 +1,56 @@
+// Copyright 2020 New Relic, Inc. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+using NewRelic.Agent.Api;
+using NewRelic.Agent.Extensions.Providers.Wrapper;
+
+namespace NewRelic.Providers.Wrapper.AzureFunction;
+
+public class FunctionsHttpProxyingMiddlewareWrapper : IWrapper
+{
+    private const string WrapperName = "FunctionsHttpProxyingMiddlewareWrapper";
+
+    public bool IsTransactionRequired => false;
+
+    public CanWrapResponse CanWrap(InstrumentedMethodInfo methodInfo)
+    {
+        return new CanWrapResponse(WrapperName.Equals(methodInfo.RequestedWrapperName));
+    }
+
+    /// <summary>
+    /// Gets request method / path for Azure function HttpTrigger invocations
+    /// in apps that use the Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore package
+    /// </summary>
+    public AfterWrappedMethodDelegate BeforeWrappedMethod(InstrumentedMethodCall instrumentedMethodCall, IAgent agent, ITransaction transaction)
+    {
+        if (agent.Configuration.AzureFunctionModeEnabled)
+        {
+            dynamic httpContext;
+            switch (instrumentedMethodCall.MethodCall.Method.MethodName)
+            {
+                case "AddHttpContextToFunctionContext":
+                    httpContext = instrumentedMethodCall.MethodCall.MethodArguments[1];
+
+                    agent.CurrentTransaction.SetRequestMethod(httpContext.Request.Method);
+                    agent.CurrentTransaction.SetUri(httpContext.Request.Path);
+                    break;
+                case "TryHandleHttpResult":
+                    if (!agent.CurrentTransaction.HasHttpResponseStatusCode) // these handlers seem to get called more than once; only set the status code one time
+                    {
+                        httpContext = instrumentedMethodCall.MethodCall.MethodArguments[2];
+                        agent.CurrentTransaction.SetHttpResponseStatusCode(httpContext.Response.StatusCode);
+                    }
+                    break;
+                case "TryHandleOutputBindingsHttpResult":
+                    if (!agent.CurrentTransaction.HasHttpResponseStatusCode) // these handlers seem to get called more than once; only set the status code one time
+                    {
+                        httpContext = instrumentedMethodCall.MethodCall.MethodArguments[1];
+                        agent.CurrentTransaction.SetHttpResponseStatusCode(httpContext.Response.StatusCode);
+                    }
+                    break;
+            }
+        }
+
+        return Delegates.NoOp;
+    }
+}

src/Agent/NewRelic/Agent/Extensions/Providers/Wrapper/AzureFunction/Instrumentation.xml

@@ -19,5 +19,18 @@ SPDX-License-Identifier: Apache-2.0
         <exactMethodMatcher methodName="Build" />
       </match>
     </tracerFactory>    
+
+    <tracerFactory name="FunctionsHttpProxyingMiddlewareWrapper">
+      <match assemblyName="Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore" className="Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore.FunctionsHttpProxyingMiddleware">
+        <exactMethodMatcher methodName="AddHttpContextToFunctionContext" />
+      </match>
+      <match assemblyName="Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore" className="Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore.FunctionsHttpProxyingMiddleware">
+        <exactMethodMatcher methodName="TryHandleHttpResult" />
+      </match>
+      <match assemblyName="Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore" className="Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore.FunctionsHttpProxyingMiddleware">
+        <exactMethodMatcher methodName="TryHandleOutputBindingsHttpResult" />
+      </match>
+      
+    </tracerFactory>
   </instrumentation>
 </extension>