AWSTracingPipelineHandler produces IL2075 warning when compiling for native AoT

[martincostello]

Issue with OpenTelemetry.Instrumentation.AWS

List of all OpenTelemetry NuGet packages and version that you are using (e.g. OpenTelemetry 1.3.2):

• OpenTelemetry.Instrumentation.AWS 1.1.0-beta.2

Runtime version:

• net6.0+

Is this a feature request or a bug?

• Feature Request
• Bug

What is the expected behavior?

When OpenTelemetry.Instrumentation.AWS is referenced in an application compiled with native AoT, there are no trim warnings.

What is the actual behavior?

1 trim warning is produced by the assembly's own code (an additional 2 are from the AWS SDK, see #1542).

C:\Coding\open-telemetry\opentelemetry-dotnet-contrib\src\OpenTelemetry.Instrumentation.AWS\Implementation\AWSTracingPipelineHandler.cs(141): Trim analysis error IL2075: OpenTelemetry.Instrumentation.AWS.Implementation.AWSTracingPipelineHandler.AddRequestSpecificInformation(Activity,IRequestContext,String): 'this' argument does not satisfy 'DynamicallyAccessedMemberTypes.PublicProperties' in call to 'System.Type.GetProperty(String)'. The return value of method 'System.Object.GetType()' does not have matching annotations. The source value must declare at least the same requirements as those declared on the target location it is assigned to. [C:\Coding\open-telemetry\opentelemetry-dotnet-contrib\test\OpenTelemetry.AotCompatibility.TestApp\OpenTelemetry.AotCompatibility.TestApp.csproj]

This warning comes from this line:

opentelemetry-dotnet-contrib/src/OpenTelemetry.Instrumentation.AWS/Implementation/AWSTracingPipelineHandler.cs

Line 137 in 8a89a69

var property = request.GetType().GetProperty(parameter);

Additional Context

Found while going through the AWS-related libraries while looking for the source of trim warnings.

I did have a look at trying to fix this one myself, but it was beyond my expertise in this case.

[martincostello]

@normj Any suggestions on how to resolve this IL2075 warning?

The only things I can think of are:

1. Suppressing the warning and trim-rooting all the AWS SDKs the application uses, which seems like it would throw away a lot of savings;
2. Adding [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)] to all of the types that derive from AmazonWebServiceRequest in the SDK assemblies (or maybe just AmazonWebServiceRequest itself?).

I tried adding the constraint on T to InvokeAsync<T>() and then adding generic versions of the problemativ method, but that only seems to work if the declaring method does that (so, PipelineHandler), and that wouldn't help with the non-generic method.

[normj]

@martincostello We know the properties will be used in the request marshallers in the SDK to create the HTTP request. So the AOT compiler can't trim the properties out and we can assume they exist. I would use the System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessage attribute and then just add an extra try/catch around the if block to cover somebody doing something really weird.

[System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessage("ReflectionAnalysis", "IL2025",
            Justification = "These reflected properties were already used during the SDK's marshallers so the properties can not be trimmed.")]

[martincostello]

Thanks Norm - I'll try that out later today.