Support for OTEL_TRACES_SAMPLER and OTEL_TRACES_SAMPLER_ARG

[Kielek]

Feature Request

Needed by AutoInstrumentation: open-telemetry/opentelemetry-dotnet-instrumentation#1091

Add support for OTEL_TRACES_SAMPLER and OTEL_TRACES_SAMPLER_ARG per specification:
https://github.com/open-telemetry/opentelemetry-specification/blob/6ce62202e5407518e19c56c445c13682ef51a51d/specification/sdk-environment-variables.md?plain=1#L46

Describe the solution you'd like
Add possibility to configure standard samplers based on env. variabla in SDK repository.

Describe alternatives you've considered
Implement it on Automatic Instrumentation side. It can be proffered way if there will be no possibility to cover all sampler types on Sdk side.

[Kielek]

@open-telemetry/dotnet-maintainers , do you have some time to provide this functionality on the Sdk side?

[anneelisabethlelievre]

Hello :), I was wondering what is the status of this PR #3635, is there any reason why it was not merged ?

[Kielek]

@anneelisabethlelievre, there is another attempt to bring it. Please check #3833,

@CodeBlanch, what is ypur plan on this PR?

[mattwhittingham]

Is there a workaround to even set these properly for an app? Currently we rolling this out library out for some production applications. A bit worried that there are no options to throttle tracing for high traffic apps. Don't need to trace everything all the time.

[cijothomas]

Is there a workaround to even set these properly for an app? Currently we rolling this out library out for some production applications. A bit worried that there are no options to throttle tracing for high traffic apps. Don't need to trace everything all the time.

https://github.com/open-telemetry/opentelemetry-dotnet/tree/main/docs/trace/customizing-the-sdk#samplers