OpenTelemetry is a new standard and API for software telemetry instrumentation and reporting. It unifies tracing, metrics and logs reporting under one unified standard API and protocol and is a result of joined effort of former OpenTracing and OpenCensus teams.
I propose that Temporal would adopt OpenTelemetry instrumentation for instrumenting and reporting metrics and tracing info for workflow execution.
The exact manner of instrumentation is something that needs to be discussed in detail, but my initiona guess is that each workflow run would be represented as a separate trace, each activity would produce a child span and it should be possible to add metadata to the trace/span context for workflows and activities.
This would give Temporal workflows very good observability story and allows it to seamlessly integrate into whatever o11y front-end or SaaS tooling.