Review and enhance tracing support for frontend (Go)

[cartersocha]

The following is a list of requirements that we need to evaluate before declaring v1 for trace telemetry. These requirements are across the entire application; Not all services will meet all requirements. Determine the relevant features for this service.

• Automatic Instrumentation is being used where appropriate. - not appropriate
• Library instrumentation is being used if automatic instrumentation is unavailable.
• Services extend automatic instrumentation.
  • New attributes/events attached to existing spans.
  • New spans are being created from existing spans.
• Automatic and Manual Context Propagation are being demonstrated.
  • Interprocess context propagation is demonstrated.
• Telemetry is not being sampled upfront.
• Telemetry is not being filtered upfront.
• Baggage is being set and read appropriately (i.e., baggage must be explicitly set as attributes on spans)

Referencing: #42

Service: https://github.com/open-telemetry/opentelemetry-demo-webstore/tree/main/src/frontend

[fatsheep9146]

1. Automatic Instrumentation is being used where appropriate.

I think the project frontend meets this requirement. Since the two main libraries that project used are both instrumented appropriately.

• google.golang.org/grpc
• github.com/gorilla/mux

the instrumentation is initialized in following lines:

• https://github.com/open-telemetry/opentelemetry-demo-webstore/blob/a49f3b8f30e344c88978d09ea851230540981b3f/src/frontend/main.go#L129
• https://github.com/open-telemetry/opentelemetry-demo-webstore/blob/a49f3b8f30e344c88978d09ea851230540981b3f/src/frontend/main.go#L166-L170

[cartersocha]

I think that covers the instrumentation library requirement. Auto instrumentation is one of those words that means something different to everyone.

In this case auto instrumentation is the agent / collector running in a sidecar right @austinlparker ?

[cartersocha]

@puckpuck could you check off the requirements you completed in your pr?

From a quick glance it seems like telemetry is not being sampled / filtered, custom attributes are being added to all spans, & library instrumentation is pre-existing. Did I miss anything & would we consider this interprocess context prop with the middleware attribute example too?

[puckpuck]

We can check off the following from the list.

• Services extend automatic instrumentation.
  • New attributes/events attached to existing spans.
  • New spans are being created from existing spans.
• Automatic and Manual Context Propagation are being demonstrated.
  • Interprocess context propagation is demonstrated.
  • Intraprocess context propagation is demonstrated.