Over at New Relic, we use the open source agent we have built. It comes with Plug transaction tracing, distributed tracing for micro-services, errors, BEAM stats, function tracing, custom attributes, alerting, etc.
In progress are a few framework integrations - Phoenix and Absinthe. Long term we want to align with the Elixir Telemetry project so we don’t need a bunch of vendor specific instrumentation packages in the ecosystem