Implement remotely configurable sampling for Jaeger exporter

[jkwatson]

details needed on what this entails....

[pavolloffay]

@jkwatson @carlosalberto please provide more details in the description.

[carlosalberto]

Details to be found in open-telemetry/opentelemetry-specification#231

[carlosalberto]

@pavolloffay Details are kinda spread that issue. Let me know what you think.

[objectiser]

Shouldn't this issue be entitled "Implement remotely configurable sampling" or something like that, and aim to provide a similar (i.e. functionally equivalent) mechanism as used in Jaeger - but applicable for any exporter used by the client?

cc @yurishkuro

[pavolloffay]

The sampling strategy is served by collector gRPC endpoint. Here is the proto definition https://github.com/jaegertracing/jaeger-idl/blob/master/proto/api_v2/sampling.proto

• RemoteSampler in Jaeger client: https://github.com/jaegertracing/jaeger-client-java/blob/46798bdf199357afc535c98b8f6734b37090bf78/jaeger-core/src/main/java/io/jaegertracing/internal/samplers/RemoteControlledSampler.java#L36
• JSON model https://github.com/jaegertracing/jaeger-client-java/blob/master/jaeger-core/src/main/java/io/jaegertracing/internal/samplers/http/SamplingStrategyResponse.java
• add serving of Jaeger sampling JSON to OTEL collector Add Support for Sampling JSON opentelemetry-collector#547

[pavolloffay]

I have started looking into this. In Jaeger this is implemented in this package https://github.com/jaegertracing/jaeger-client-java/tree/46798bdf199357afc535c98b8f6734b37090bf78/jaeger-core/src/main/java/io/jaegertracing/internal/samplers.

It actually requires these classes: RemoteControlledSampler. RateLimitingSampler, PerOperationSampler, GuaranteedThroughputSampler.

I am wondering whether it would be better to depend on jaeger-core artifact https://mvnrepository.com/artifact/io.jaegertracing/jaeger-core/1.2.0 and just create the adapter for RemoteControlledSampler.

@bogdandrutu any concerns on depending on jaeger-core?

[yurishkuro]

My preference would be for OTel to be a clean cut, not to bundle Jaeger.

Also, Jaeger sampling is upfront, I don't understand how it can be done in the exporter.

[pavolloffay]

It won't be in the exporter. It will be OTEL sampler implementation, we should decide whether it will be located in the same package as Jaeger exporter or a different one.