From 66373c2eb91dc372e84520568cb58264942fcc82 Mon Sep 17 00:00:00 2001
From: fpetkovski <filip.petkovsky@gmail.com>
Date: Tue, 19 Aug 2025 12:46:48 +0200
Subject: [PATCH] Add info metric for client-go version

KSM supports a range of Kubernetes versions which makes it important to
keep up with new versions as clusters upgrade.

In order to allow for alerting on unsupported cluster versions, this commit
adds an info metric for the client-go version used by KSM. This way users can
set up alerts if the cluster in which KSM is running is outside of the supported range.

Signed-off-by: fpetkovski <filip.petkovsky@gmail.com>
---
 Makefile          |  6 ++++--
 pkg/app/server.go | 14 ++++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index fbbe669a7..1d77deb45 100644
--- a/Makefile
+++ b/Makefile
@@ -20,10 +20,12 @@ MULTI_ARCH_IMG = $(IMAGE)-$(ARCH)
 USER ?= $(shell id -u -n)
 HOST ?= $(shell hostname)
 MARKDOWNLINT_CLI2_VERSION = 0.18.1
+CLIENT_GO_VERSION = $(shell go list -m -f '{{.Version}}' k8s.io/client-go)
+KSM_MODULE = $(shell go list -m)
 
 DOCKER_CLI ?= docker
 PROMTOOL_CLI ?= promtool
-GOMPLATE_CLI ?= go tool github.com/hairyhenderson/gomplate/v4/cmd/gomplate 
+GOMPLATE_CLI ?= go tool github.com/hairyhenderson/gomplate/v4/cmd/gomplate
 GOJSONTOYAML_CLI ?= go tool github.com/brancz/gojsontoyaml
 EMBEDMD_CLI ?= go tool github.com/campoy/embedmd
 JSONNET_CLI ?= go tool github.com/google/go-jsonnet/cmd/jsonnet
@@ -69,7 +71,7 @@ doccheck: generate validate-template
 	@echo OK
 
 build-local:
-	GOOS=$(OS) GOARCH=$(ARCH) CGO_ENABLED=0 go build -ldflags "-s -w -X ${PKG}/version.Version=${TAG} -X ${PKG}/version.Revision=${GIT_COMMIT} -X ${PKG}/version.Branch=${BRANCH} -X ${PKG}/version.BuildUser=${USER}@${HOST} -X ${PKG}/version.BuildDate=${BUILD_DATE}" -o kube-state-metrics
+	GOOS=$(OS) GOARCH=$(ARCH) CGO_ENABLED=0 go build -ldflags "-s -w -X ${PKG}/version.Version=${TAG} -X ${PKG}/version.Revision=${GIT_COMMIT} -X ${PKG}/version.Branch=${BRANCH} -X ${PKG}/version.BuildUser=${USER}@${HOST} -X ${PKG}/version.BuildDate=${BUILD_DATE} -X ${PKG}/version.BuildDate=${BUILD_DATE} -X ${KSM_MODULE}/pkg/app.ClientGoVersion=${CLIENT_GO_VERSION}" -o kube-state-metrics
 
 build: kube-state-metrics
 
diff --git a/pkg/app/server.go b/pkg/app/server.go
index 31831ef73..a33ddf8e2 100644
--- a/pkg/app/server.go
+++ b/pkg/app/server.go
@@ -63,6 +63,10 @@ import (
 	"k8s.io/kube-state-metrics/v2/pkg/util/proc"
 )
 
+// ClientGoVersion is the version for the client-go library used by KSM. This
+// value is set at build time using go build flags.
+var ClientGoVersion = "unknown"
+
 const (
 	metricsPath = "/metrics"
 	healthzPath = "/healthz"
@@ -86,6 +90,16 @@ func RunKubeStateMetricsWrapper(ctx context.Context, opts *options.Options) erro
 func RunKubeStateMetrics(ctx context.Context, opts *options.Options) error {
 	ksmMetricsRegistry := prometheus.NewRegistry()
 	ksmMetricsRegistry.MustRegister(versionCollector.NewCollector("kube_state_metrics"))
+
+	clientGoVersion := promauto.With(ksmMetricsRegistry).NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "kube_state_metrics_client_go_info",
+			Help: "An info metric for the client-go version used by kube-state-metrics",
+		},
+		[]string{"version"},
+	)
+	clientGoVersion.WithLabelValues(ClientGoVersion).Set(1)
+
 	durationVec := promauto.With(ksmMetricsRegistry).NewHistogramVec(
 		prometheus.HistogramOpts{
 			Name:        "http_request_duration_seconds",