Merge pull request kubernetes#128430 from richabanker/kubelet-metrics-slis-fix

do not install handler for '/metrics/slis' endpoint using sync.Once

Author: k8s-ci-robot

pkg/kubelet/server/auth_test.go

@@ -137,6 +137,7 @@ func AuthzTestCases(fineGrained bool) []AuthzTestCase {
 		"/logs/":                              {"log"},
 		"/logs/{logpath:*}":                   {"log"},
 		"/metrics":                            {"metrics"},
+		"/metrics/slis":                       {"metrics"},
 		"/metrics/cadvisor":                   {"metrics"},
 		"/metrics/probes":                     {"metrics"},
 		"/metrics/resource":                   {"metrics"},

pkg/kubelet/server/server_test.go

@@ -1641,3 +1641,19 @@ func TestFineGrainedAuthz(t *testing.T) {
 		})
 	}
 }
+
+func TestNewServerRegistersMetricsSLIsEndpointTwice(t *testing.T) {
+	host := &fakeKubelet{
+		hostnameFunc: func() string {
+			return "127.0.0.1"
+		},
+	}
+	resourceAnalyzer := stats.NewResourceAnalyzer(nil, time.Minute, &record.FakeRecorder{})
+
+	server1 := NewServer(host, resourceAnalyzer, nil, nil)
+	server2 := NewServer(host, resourceAnalyzer, nil, nil)
+
+	// Check if both servers registered the /metrics/slis endpoint
+	assert.Contains(t, server1.restfulCont.RegisteredHandlePaths(), "/metrics/slis", "First server should register /metrics/slis")
+	assert.Contains(t, server2.restfulCont.RegisteredHandlePaths(), "/metrics/slis", "Second server should register /metrics/slis")
+}

staging/src/k8s.io/component-base/metrics/prometheus/slis/routes.go

@@ -38,8 +38,8 @@ type SLIMetrics struct{}
 func (s SLIMetrics) Install(m mux) {
 	installOnce.Do(func() {
 		Register(Registry)
-		m.Handle("/metrics/slis", metrics.HandlerFor(Registry, metrics.HandlerOpts{}))
 	})
+	m.Handle("/metrics/slis", metrics.HandlerFor(Registry, metrics.HandlerOpts{}))
 }
 
 type SLIMetricsWithReset struct{}
@@ -48,6 +48,6 @@ type SLIMetricsWithReset struct{}
 func (s SLIMetricsWithReset) Install(m mux) {
 	installWithResetOnce.Do(func() {
 		Register(Registry)
-		m.Handle("/metrics/slis", metrics.HandlerWithReset(Registry, metrics.HandlerOpts{}))
 	})
+	m.Handle("/metrics/slis", metrics.HandlerWithReset(Registry, metrics.HandlerOpts{}))
 }

staging/src/k8s.io/component-base/metrics/prometheus/slis/routes_test.go

@@ -0,0 +1,44 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package slis
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type mockMux struct {
+	handledPaths []string
+}
+
+func (m *mockMux) Handle(path string, handler http.Handler) {
+	m.handledPaths = append(m.handledPaths, path)
+}
+
+func TestSLIMetrics_Install(t *testing.T) {
+	m := &mockMux{}
+	s := SLIMetrics{}
+
+	s.Install(m)
+	assert.Equal(t, []string{"/metrics/slis"}, m.handledPaths)
+
+	s.Install(m)
+	// Assert that the path is registered twice for the 2 calls made to Install().
+	assert.Equal(t, []string{"/metrics/slis", "/metrics/slis"}, m.handledPaths, "Should handle the path twice.")
+}