Adding AWS Lambda Configurations prevents adding resource attributes via environment variable

[DanDanN00dle]

Issue with OpenTelemetry.Contrib.Instrumentation.AWSLambda

Using:

• OpenTelemetry 1.3.0-beta.2
• OpenTelemetry.Contrib.Instrumentation.AWS 1.0.1
• OpenTelemetry.Contrib.Instrumentation.AWSLambda 1.1.0-beta1
• OpenTelemetry.Exporter.Console 1.3.0-beta.2
• OpenTelemetry.Exporter.OpenTelemetryProtocol 1.3.0-beta.2
• OpenTelemetry.Exporter.OpenTelemetryProtocol.Logs 1.0.0-rc9.3
• OpenTelemetry.Instrumentation.MySqlData 1.0.0-beta.2

On runtime net6.0

Is this a feature request or a bug?

• Feature Request
• Bug

What is the expected behavior?

When setting the environment variable OTEL_RESOURCE_ATTRIBUTES for the lambda I expect to be able to add additional resource attributes to my lambda (per the specificaton).

What is the actual behavior?

The resource does not have the additional attributes specified in the environment variable.

        [Fact]
        public void TestResourceAdditionalAttributesFromEnvVar()
        {
            Environment.SetEnvironmentVariable("OTEL_RESOURCE_ATTRIBUTES", "application=TestApplication");

            using (var tracerProvider = Sdk.CreateTracerProviderBuilder()
                .AddAWSLambdaConfigurations()
                .Build())
            {
                var result = AWSLambdaWrapper.Trace(tracerProvider, this.sampleHandlers.SampleHandlerSyncReturn, "TestStream", this.sampleLambdaContext);
                var resource = tracerProvider.GetResource();
                this.AssertResourceAttributes(resource, new Dictionary<string, object> { ["application"] = "TestApplication" });
            }
        }

See test case.

[mechie]

I think this issue is caused by setting a new ResourceBuilder instead of modifying the existing one:

builder.SetResourceBuilder(ResourceBuilder
    .CreateEmpty()
    .AddTelemetrySdk()
    .AddAttributes(AWSLambdaResourceDetector.Detect()));

We can bypass by adding this line after .AddAWSLambdaConfigurations(), though I'm unsure whether there's other side effects from the original Sdk builder (it's a TracerProviderServiceCollectionBuilder instead of a plain ResourceBuilder, for starters):

.ConfigureResource((resource) => resource.AddEnvironmentVariableDetector())

Should AddAWSLambdaConfigurations ConfigureResource as well?

[Oberon00]

I think this issue is why I originally created open-telemetry/opentelemetry-dotnet#2909
PRs to switch the instrumentation to use this are welcome (an OTel upgrade might be necessary)