Add prow instructions

docs/opentelemetry.md

@@ -27,3 +27,28 @@ go run . --src /tmp/trace --run docker-jaeger
 
 Not everything is instrumented yet, and not all the traces are fully joined up (we need to thread more contexts through more methods),
 but you should be able to start to explore the operations that we run and their performance.
+
+## Prow Jobs
+
+Tracing is enabled in the kops prow jobs. `.otel` files are created during job execution and included as job artifacts in the `otlp` subdirectory.
+
+Example:
+
+```
+https://gcsweb.k8s.io/gcs/kubernetes-jenkins/pr-logs/pull/kops/16204/presubmit-kops-aws-scale-amazonvpc-using-cl2/1742962895290896384/artifacts/otlp/
+```
+
+Download these files to a local directory, either with `gsutil` or through a web browser
+
+```
+mkdir /tmp/job-traces
+
+gsutil cp -r gs://kubernetes-jenkins/pr-logs/pull/kops/16204/presubmit-kops-aws-scale-amazonvpc-using-cl2/1742962895290896384/artifacts/otlp/ /tmp/job-traces
+```
+
+Then run the trace server as normal:
+
+```sh
+cd tools/otel/traceserver
+go run . --src /tmp/traces --run jaeger
+```