How does Envoy-based tracing work?

For Envoy-based tracing integrations, Envoy (the sidecar proxy) sends tracing information directly to tracing backends on behalf of the applications being proxied.

Envoy:

• generates request IDs and trace headers (i.e., X-B3-TraceId) for requests as they flow through the proxy
• generates trace spans for each request based on request and response metadata (i.e., response time)
• sends the generated trace spans to the tracing backends
• forwards the trace headers to the proxied application

Istio supports OpenTelemetry and compatible backends including Jaeger. Other supported platforms include Zipkin and Apache SkyWalking.