feat: Integrate Tailcall with OpenTelemetry

[kevinmichaelchen]

# step 1 - start up servers
make

# step 2 - start tailcall
task run:tailcall

# step 3 - start docs
(cd docs && bun install && bun dev)

Run this GraphQL mutation in the GraphQL Playground.

Tailcall will export telemetry via gRPC to the local OTel Collector's port 4317. A trace for tailcall will appear in Jaeger.

[kevinmichaelchen]

the otel collector should be able to receive telemetry via http on port 4318

https://github.com/kevinmichaelchen/temporal-saga-grpc/blob/main/docker-compose.yml#L39

[kevinmichaelchen]

Trace context propagation does not appear to be working. I see the Tailcall trace with only 3 spans, and it's missing all the other spans.

Tailcall spans

Other spans

I'm using Temporal's default trace propagator, which is really just the default OTel propagator that uses W3C:

import "go.temporal.io/sdk/contrib/opentelemetry"

// Set the same Trace Propagator that Temporal uses by default
otel.SetTextMapPropagator(opentelemetry.DefaultTextMapPropagator)

[kevinmichaelchen]

logging http headers

INFO received request headers="map[Accept:[*/*] Connect-Protocol-Version:[1] Content-Type:[application/json] Host:[localhost:8081] User-Agent:[Tailcall/1.0]]"

possibilities

• tailcall isn't sending trace headers
  • tailcall uses tokio under the hood. tried running tailcall w/ stdout telemetry and tokio is clearly generating spans with traceId and spanId. but no such headers show up. is tokio not sending them?
• headers are getting lost during vanguard transcoding
  • can't find any logic that would cause headers to get filtered out