fix: don't leave open file descriptors after collecting metrics

cmd/cache/main.go

@@ -13,7 +13,6 @@ import (
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
 
 	ctrl "sigs.k8s.io/controller-runtime"
-	"sigs.k8s.io/controller-runtime/pkg/healthz"
 	"sigs.k8s.io/controller-runtime/pkg/log/zap"
 	"sigs.k8s.io/controller-runtime/pkg/webhook"
 
@@ -94,11 +93,11 @@ func main() {
 	mgr.GetWebhookServer().Register("/mutate-core-v1-pod", &webhook.Admission{Handler: &imageRewriter})
 	//+kubebuilder:scaffold:builder
 
-	if err := mgr.AddHealthzCheck("healthz", healthz.Ping); err != nil {
+	if err := mgr.AddHealthzCheck("healthz", controllers.MakeChecker(controllers.Healthz)); err != nil {
 		setupLog.Error(err, "unable to set up health check")
 		os.Exit(1)
 	}
-	if err := mgr.AddReadyzCheck("readyz", healthz.Ping); err != nil {
+	if err := mgr.AddReadyzCheck("readyz", controllers.MakeChecker(controllers.Readyz)); err != nil {
 		setupLog.Error(err, "unable to set up ready check")
 		os.Exit(1)
 	}

controllers/collector.go

@@ -2,7 +2,6 @@ package controllers
 
 import (
 	"context"
-	"net/http"
 	"strconv"
 
 	kuikenixiov1alpha1 "github.com/enix/kube-image-keeper/api/v1alpha1"
@@ -46,7 +45,7 @@ var (
 		Name:      "up",
 		Help:      "Whether or not this replica is healthy.",
 	}, func() float64 {
-		if resp, err := http.Get("http://" + ProbeAddr + "/healthz"); err != nil || (resp != nil && resp.StatusCode != http.StatusOK) {
+		if err := Healthz(); err != nil {
 			return 0
 		}
 		return 1

controllers/healthz.go

@@ -0,0 +1,21 @@
+package controllers
+
+import (
+	"net/http"
+
+	"sigs.k8s.io/controller-runtime/pkg/healthz"
+)
+
+func MakeChecker(check func() error) healthz.Checker {
+	return func(req *http.Request) error {
+		return check()
+	}
+}
+
+func Healthz() error {
+	return nil
+}
+
+func Readyz() error {
+	return nil
+}