From f04bb71878e6b77b5bec65565bc636ec39c6de4c Mon Sep 17 00:00:00 2001
From: Sascha Grunert <sgrunert@redhat.com>
Date: Tue, 29 Nov 2022 13:03:13 +0100
Subject: [PATCH] Tracing: sample always in `hack/local-up-cluster.sh`

If the feature gate `KubeletTracing` is enabled, then we should default
to a sample rate of 1 million per million, which will sample everything:

https://github.com/open-telemetry/opentelemetry-go/blob/aa868d5/sdk/trace/sampling.go#L107-L110

This helps to easier spin-up a cluster with tracing enabled by exporting
`FEATURE_GATES="KubeletTracing=true"`.

Related docs: https://k8s.io/docs/concepts/cluster-administration/system-traces/#kubelet-traces

Signed-off-by: Sascha Grunert <sgrunert@redhat.com>
---
 hack/local-up-cluster.sh | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/hack/local-up-cluster.sh b/hack/local-up-cluster.sh
index 6ec7f1ded28..20355a5074d 100755
--- a/hack/local-up-cluster.sh
+++ b/hack/local-up-cluster.sh
@@ -753,6 +753,15 @@ runtimeRequestTimeout: "${RUNTIME_REQUEST_TIMEOUT}"
 staticPodPath: "${POD_MANIFEST_PATH}"
 resolvConf: "${KUBELET_RESOLV_CONF}"
 EOF
+
+    if [[ "$FEATURE_GATES" == *KubeletTracing=true* ]]; then
+        cat <<EOF >> /tmp/kubelet.yaml
+tracing:
+  endpoint: localhost:4317 # the default value
+  samplingRatePerMillion: 1000000 # sample always
+EOF
+    fi
+
     {
       # authentication
       echo "authentication:"