What is required for distributed tracing with Istio?

Istio enables reporting of trace spans for workload-to-workload communications within a mesh. However, in order for various trace spans to be stitched together for a complete view of the traffic flow, applications must propagate the trace context between incoming and outgoing requests.

In particular, Istio relies on applications to forward the Envoy-generated request ID, and standard headers. These headers include:

• x-request-id
• traceparent
• tracestate

Zipkin users must ensure they propagate the B3 trace headers.

• x-b3-traceid
• x-b3-spanid
• x-b3-parentspanid
• x-b3-sampled
• x-b3-flags
• b3

Header propagation may be accomplished through client libraries, such as OpenTelemetry. It can also be accomplished manually, as documented in the Distributed Tracing task.