Serve sampling strategies

[pavolloffay]

Serve sampling strategies file

At the moment collector just proxies calls. Done in open-telemetry/opentelemetry-collector#448

[pavolloffay]

Might be done in open-telemetry/opentelemetry-collector#500

[objectiser]

This has been done as part of open-telemetry/opentelemetry-collector#547 - however it only works over gRPC.

Now that /api/sampling is available in Jaeger collector, since 1.17.0, that should be supported aswell.

cc @joe-elliott

[joe-elliott]

The opentelemetry collector supports both http proxy (jaeger agent) and GRPC (jaeger collector) for serving sampling strategies. It's a little strange, but technically an operator could configure their opentelemetry collector to proxy to itself. The config would look something like:

receivers:
  jaeger:
    protocols:
      grpc:
    remote_sampling:
      fetch_endpoint: "localhost:14250"
      strategy_file: "/etc/strategies.json"

This work was done before we knew about the jaeger-opentelemetry-collector. Now that it exists maybe we should reevaluate some of the functionality in the collector.

[pavolloffay]

@objectiser can this be closed?

[objectiser]

Not sure it is an ideal solution but provides a workaround, so guess we can close and open issues in the core repo to make improvements.