fix: Update Profiler to check whether Azure function mode support is enabled

src/Agent/NewRelic/Home/Home.csproj

@@ -13,7 +13,7 @@
   </Target>
 
   <ItemGroup>
-    <PackageReference Include="NewRelic.Agent.Internal.Profiler" Version="10.29.0.66"/>
+    <PackageReference Include="NewRelic.Agent.Internal.Profiler" Version="10.31.0.15"/>
   </ItemGroup>
 
 </Project>

src/Agent/NewRelic/Profiler/Configuration/Configuration.h

@@ -605,13 +605,17 @@ namespace NewRelic { namespace Profiler { namespace Configuration {
                 return false;
             }
 
-            if (IsAzureFunction()) {
-                auto retVal = ShouldInstrumentAzureFunction(processPath, appPoolId, commandLine);
-                if (retVal == 0) {
-                    return false;
-                }
-                if (retVal == 1) {
-                    return true;
+            if (IsAzureFunction())
+            {
+                if (IsAzureFunctionModeEnabled()) // if not explicitly enabled, fall back to "legacy" behavior
+                {
+                    auto retVal = ShouldInstrumentAzureFunction(processPath, appPoolId, commandLine);
+                    if (retVal == 0) {
+                        return false;
+                    }
+                    if (retVal == 1) {
+                        return true;
+                    }
                 }
             }
 
@@ -622,6 +626,17 @@ namespace NewRelic { namespace Profiler { namespace Configuration {
             return true;
         }
 
+        bool IsAzureFunctionModeEnabled() const
+        {
+            auto azureFunctionModeEnabled = _systemCalls->TryGetEnvironmentVariable(_X("NEW_RELIC_AZURE_FUNCTION_MODE_ENABLED"));
+
+            if (azureFunctionModeEnabled == nullptr || azureFunctionModeEnabled->length() == 0) {
+                return false;
+            }
+
+            return Strings::AreEqualCaseInsensitive(*azureFunctionModeEnabled, _X("true")) || Strings::AreEqualCaseInsensitive(*azureFunctionModeEnabled, _X("1"));
+        }
+
         bool IsAzureFunction() const
         {
             // Azure Functions sets the FUNCTIONS_WORKER_RUNTIME environment variable to "dotnet-isolated" when running in the .NET worker.

src/Agent/NewRelic/Profiler/ConfigurationTest/ConfigurationTest.cpp

@@ -73,6 +73,47 @@ namespace NewRelic { namespace Profiler { namespace Configuration { namespace Te
             Assert::IsFalse(configuration.ShouldInstrument(L"foo.exe", L"", L"", L"", false));
         }
 
+        // tests to verify that "legacy" behavior (before azure function support) is retained.
+        // If NEW_RELIC_AZURE_FUNCTION_MODE_ENABLED environment variable is not set or is set to false,
+        // we should behave as if no azure function support has been added.
+        TEST_METHOD(azure_function_should_behave_as_legacy_if_azure_function_mode_not_specified)
+        {
+            std::wstring configurationXml(L"\
+    <?xml version=\"1.0\"?>\
+    <configuration>\
+        <log level=\"deBug\"/>\
+    </configuration>\
+    ");
+
+            auto systemCalls = std::make_shared<NewRelic::Profiler::Logger::Test::SystemCalls>();
+            systemCalls->environmentVariables[L"FUNCTIONS_WORKER_RUNTIME"] = L"dotnet-isolated";
+
+            Configuration configuration(configurationXml, _missingConfig, L"", systemCalls);
+
+            Assert::IsTrue(configuration.ShouldInstrument(L"functionsnethost.exe", L"", L"", L"blah blah blah FooBarBaz blah blah blah", true));
+        }
+
+        // tests to verify that "legacy" behavior (before azure function support) is retained.
+        // If NEW_RELIC_AZURE_FUNCTION_MODE_ENABLED environment variable is not set or is set to false,
+        // we should behave as if no azure function support has been added.
+        TEST_METHOD(azure_function_should_behave_as_legacy_if_azure_function_mode_disabled)
+        {
+            std::wstring configurationXml(L"\
+    <?xml version=\"1.0\"?>\
+    <configuration>\
+        <log level=\"deBug\"/>\
+    </configuration>\
+    ");
+
+            auto systemCalls = std::make_shared<NewRelic::Profiler::Logger::Test::SystemCalls>();
+            systemCalls->environmentVariables[L"FUNCTIONS_WORKER_RUNTIME"] = L"dotnet-isolated";
+            systemCalls->environmentVariables[L"NEW_RELIC_AZURE_FUNCTION_MODE_ENABLED"] = L"0";
+
+            Configuration configuration(configurationXml, _missingConfig, L"", systemCalls);
+
+            Assert::IsTrue(configuration.ShouldInstrument(L"functionsnethost.exe", L"", L"", L"blah blah blah FooBarBaz blah blah blah", true));
+        }
+
         TEST_METHOD(should_not_instrument_azure_function_app_pool_id_in_commandline)
         {
             std::wstring configurationXml(L"\
@@ -84,6 +125,7 @@ namespace NewRelic { namespace Profiler { namespace Configuration { namespace Te
 
             auto systemCalls = std::make_shared<NewRelic::Profiler::Logger::Test::SystemCalls>();
             systemCalls->environmentVariables[L"FUNCTIONS_WORKER_RUNTIME"] = L"dotnet-isolated";
+            systemCalls->environmentVariables[L"NEW_RELIC_AZURE_FUNCTION_MODE_ENABLED"] = L"true";
 
             Configuration configuration(configurationXml, _missingConfig, L"", systemCalls);
 
@@ -101,6 +143,7 @@ namespace NewRelic { namespace Profiler { namespace Configuration { namespace Te
 
             auto systemCalls = std::make_shared<NewRelic::Profiler::Logger::Test::SystemCalls>();
             systemCalls->environmentVariables[L"FUNCTIONS_WORKER_RUNTIME"] = L"dotnet-isolated";
+            systemCalls->environmentVariables[L"NEW_RELIC_AZURE_FUNCTION_MODE_ENABLED"] = L"true";
 
             Configuration configuration(configurationXml, _missingConfig, L"", systemCalls);
 
@@ -118,6 +161,7 @@ namespace NewRelic { namespace Profiler { namespace Configuration { namespace Te
 
             auto systemCalls = std::make_shared<NewRelic::Profiler::Logger::Test::SystemCalls>();
             systemCalls->environmentVariables[L"FUNCTIONS_WORKER_RUNTIME"] = L"dotnet-isolated";
+            systemCalls->environmentVariables[L"NEW_RELIC_AZURE_FUNCTION_MODE_ENABLED"] = L"true";
 
             Configuration configuration(configurationXml, _missingConfig, L"", systemCalls);
 
@@ -135,6 +179,7 @@ namespace NewRelic { namespace Profiler { namespace Configuration { namespace Te
 
             auto systemCalls = std::make_shared<NewRelic::Profiler::Logger::Test::SystemCalls>();
             systemCalls->environmentVariables[L"FUNCTIONS_WORKER_RUNTIME"] = L"dotnet-isolated";
+            systemCalls->environmentVariables[L"NEW_RELIC_AZURE_FUNCTION_MODE_ENABLED"] = L"true";
 
             Configuration configuration(configurationXml, _missingConfig, L"", systemCalls);
 

tests/Agent/IntegrationTests/IntegrationTests/AzureFunction/AzureFunctionHttpTriggerTests.cs

@@ -31,12 +31,26 @@ protected AzureFunctionHttpTriggerTestsBase(TFixture fixture, ITestOutputHelper
         _fixture.AddActions(
             setupConfiguration: () =>
             {
-                new NewRelicConfigModifier(fixture.DestinationNewRelicConfigFilePath)
+                var configModifier = new NewRelicConfigModifier(fixture.DestinationNewRelicConfigFilePath);
+                configModifier
                     .ForceTransactionTraces()
                     .ConfigureFasterTransactionTracesHarvestCycle(20)
                     .ConfigureFasterMetricsHarvestCycle(15)
                     .ConfigureFasterSpanEventsHarvestCycle(15)
                     .SetLogLevel("finest");
+
+                // This is a bit of a kludge. When azure function instrumentation is disabled,
+                // the agent instruments *two* processes: the azure function host (func.exe) and the actual function app.
+                // Both processes use the same config files, so explicitly setting the log file name forces both
+                // processes to log to the same file, which makes it easier to verify that the
+                // actual function app is not being instrumented when the Invoke() method gets hit.
+                //
+                // Ideally, we'd prefer to look for the specific log file for the azure function app, but that's less trivial
+                // and not worth the effort for this one test.
+                if (!_fixture.AzureFunctionModeEnabled)
+                {
+                    configModifier.SetLogFileName("azure_function_instrumentation_disabled.log");
+                }
             },
             exerciseApplication: () =>
             {
@@ -138,8 +152,8 @@ public void Test_SimpleInvocationMode()
 
         if (!_fixture.AzureFunctionModeEnabled) // look for a specific log line that indicates azure function mode is disabled
         {
-            var disabledLogLine = _fixture.AgentLog.TryGetLogLine(AgentLogBase.AzureFunctionModeDisabledLogLineRegex);
-            Assert.NotNull(disabledLogLine);
+            var disabledLogLines = _fixture.AgentLog.TryGetLogLines(AgentLogBase.AzureFunctionModeDisabledLogLineRegex);
+            Assert.Single(disabledLogLines);
         }
     }