Add AWS_LAMBDA_DOTNET_DISABLE_MEMORY_LIMIT_CHECK env variable to turn…

… off the .NET 8 memory adjustment code

Libraries/src/Amazon.Lambda.RuntimeSupport/Amazon.Lambda.RuntimeSupport.csproj

@@ -4,7 +4,7 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;net5.0;net6.0;net8.0</TargetFrameworks>
-    <VersionPrefix>1.9.0</VersionPrefix>
+    <VersionPrefix>1.9.1</VersionPrefix>
     <Description>Provides a bootstrap and Lambda Runtime API Client to help you to develop custom .NET Core Lambda Runtimes.</Description>
     <AssemblyTitle>Amazon.Lambda.RuntimeSupport</AssemblyTitle>
     <AssemblyName>Amazon.Lambda.RuntimeSupport</AssemblyName>

Libraries/src/Amazon.Lambda.RuntimeSupport/Bootstrap/Constants.cs

@@ -24,6 +24,8 @@ internal class Constants
         // variable should never be set when function is deployed to Lambda.
         internal const string ENVIRONMENT_VARIABLE_AWS_LAMBDA_DOTNET_DEBUG_RUN_ONCE = "AWS_LAMBDA_DOTNET_DEBUG_RUN_ONCE";
 
+        internal const string ENVIRONMENT_VARIABLE_DISABLE_HEAP_MEMORY_LIMIT = "AWS_LAMBDA_DOTNET_DISABLE_MEMORY_LIMIT_CHECK";
+
         internal const string ENVIRONMENT_VARIABLE_AWS_LAMBDA_DOTNET_PREJIT = "AWS_LAMBDA_DOTNET_PREJIT";
         internal const string ENVIRONMENT_VARIABLE_AWS_LAMBDA_INITIALIZATION_TYPE = "AWS_LAMBDA_INITIALIZATION_TYPE";
         internal const string ENVIRONMENT_VARIABLE_LANG = "LANG";

Libraries/src/Amazon.Lambda.RuntimeSupport/Bootstrap/LambdaBootstrap.cs

@@ -265,6 +265,15 @@ private void AdjustMemorySettings()
         {
             try
             {
+                // Check the environment variable to see if the user has opted out of RuntimeSupport adjusting 
+                // the heap memory limit to match the Lambda configured environment. This can be useful for situations
+                // where the Lambda environment is being emulated for testing and more then just single Lambda function
+                // is running in the process. For example running a test runner over a series of Lambda emulated invocations.
+                var value = Environment.GetEnvironmentVariable(Constants.ENVIRONMENT_VARIABLE_DISABLE_HEAP_MEMORY_LIMIT);
+                if (string.Equals(value, "true", StringComparison.OrdinalIgnoreCase))
+                    return;
+
+
                 int lambdaMemoryInMb;
                 if (!int.TryParse(Environment.GetEnvironmentVariable(LambdaEnvironment.EnvVarFunctionMemorySize), out lambdaMemoryInMb))
                     return;

Libraries/test/Amazon.Lambda.RuntimeSupport.Tests/Amazon.Lambda.RuntimeSupport.IntegrationTests/CustomRuntimeTests.cs

@@ -95,6 +95,7 @@ protected virtual async Task TestAllHandlersAsync()
                     if(_targetFramework == TargetFramework.NET8)
                     {
                         await RunMaxHeapMemoryCheck(lambdaClient, "GetTotalAvailableMemoryBytes");
+                        await RunWithoutMaxHeapMemoryCheck(lambdaClient, "GetTotalAvailableMemoryBytes");
                         await RunMaxHeapMemoryCheckWithCustomMemorySettings(lambdaClient, "GetTotalAvailableMemoryBytes");
                     }
 
@@ -151,6 +152,22 @@ private async Task RunMaxHeapMemoryCheck(AmazonLambdaClient lambdaClient, string
             }
         }
 
+        private async Task RunWithoutMaxHeapMemoryCheck(AmazonLambdaClient lambdaClient, string handler)
+        {
+            await UpdateHandlerAsync(lambdaClient, handler, new Dictionary<string, string> { { "AWS_LAMBDA_DOTNET_DISABLE_MEMORY_LIMIT_CHECK", "true" } });
+            var invokeResponse = await InvokeFunctionAsync(lambdaClient, JsonConvert.SerializeObject(""));
+            using (var responseStream = invokeResponse.Payload)
+            using (var sr = new StreamReader(responseStream))
+            {
+                string payloadStr = (await sr.ReadToEndAsync()).Replace("\"", "");
+                // Function payload response will have format {Handler}-{MemorySize}.
+                // To check memory split on the - and grab the second token representing the memory size.
+                var tokens = payloadStr.Split('-');
+                var memory = long.Parse(tokens[1]);
+                Assert.False(memory <= BaseCustomRuntimeTest.FUNCTION_MEMORY_MB * 1048576);
+            }
+        }
+
         private async Task RunMaxHeapMemoryCheckWithCustomMemorySettings(AmazonLambdaClient lambdaClient, string handler)
         {
             // Set the .NET GC environment variable to say there is 256 MB of memory. The function is deployed with 512 but since the user set