POC: statusz for apiserver

kubernetes · Jul 20, 2024 · ca731e7 · ca731e7
1 parent 14b34fc
commit ca731e7
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Showing 4 changed files with 314 additions and 0 deletions.
diff --git a/staging/src/k8s.io/apiserver/pkg/server/config.go b/staging/src/k8s.io/apiserver/pkg/server/config.go
@@ -78,6 +78,7 @@ import (
 	"k8s.io/component-base/logs"
 	"k8s.io/component-base/metrics/features"
 	"k8s.io/component-base/metrics/prometheus/slis"
+	"k8s.io/component-base/statusz"
 	"k8s.io/component-base/tracing"
 	"k8s.io/klog/v2"
 	openapicommon "k8s.io/kube-openapi/pkg/common"
@@ -1093,6 +1094,8 @@ func installAPI(s *GenericAPIServer, c *Config) {
 	}
 
 	if c.EnableMetrics {
+		statuzOpts := statuszOptions()
+		statusz.Statusz{}.Install(s.Handler.NonGoRestfulMux, statuzOpts)
 		if c.EnableProfiling {
 			routes.MetricsWithReset{}.Install(s.Handler.NonGoRestfulMux)
 			slis.SLIMetricsWithReset{}.Install(s.Handler.NonGoRestfulMux)
@@ -1185,3 +1188,10 @@ func SetHostnameFuncForTests(name string) {
 		return
 	}
 }
+
+func statuszOptions() statusz.Options {
+	return statusz.Options{
+		ComponentName: "apiserver",
+		StartTime:     time.Now(),
+	}
+}
diff --git a/staging/src/k8s.io/component-base/statusz/registry.go b/staging/src/k8s.io/component-base/statusz/registry.go
@@ -0,0 +1,125 @@
+/*
+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 statusz
+
+import (
+	"context"
+	"fmt"
+	"html/template"
+	"io"
+	"sync"
+	"time"
+)
+
+type statuszRegistry struct {
+	lock     sync.Mutex
+	options  Options
+	sections []section
+}
+
+type section struct {
+	Title string
+	Func  func(context.Context, io.Writer) error
+}
+
+func Register(opts Options) *statuszRegistry {
+	registry := &statuszRegistry{
+		options: opts,
+	}
+	registry.addSection("default", defaultSection)
+	return registry
+}
+
+func (reg *statuszRegistry) addSection(title string, f func(ctx context.Context, wr io.Writer, opts Options) error) error {
+	reg.lock.Lock()
+	defer reg.lock.Unlock()
+	reg.sections = append(reg.sections, section{
+		Title: title,
+		Func: func(ctx context.Context, wr io.Writer) error {
+			err := f(ctx, wr, reg.options)
+			if err != nil {
+				failErr := template.Must(template.New("").Parse("<code>invalid HTML: {{.}}</code>")).Execute(wr, err)
+				if failErr != nil {
+					return fmt.Errorf("go/server: couldn't execute the error template for %q: %v (couldn't get HTML fragment: %v)", title, failErr, err)
+				}
+				return err
+			}
+			return nil
+		},
+	})
+	return nil
+}
+
+func defaultSection(ctx context.Context, wr io.Writer, opts Options) error {
+	var data struct {
+		ServerName string
+		StartTime  string
+		Uptime     string
+	}
+
+	data.ServerName = opts.ComponentName
+	data.StartTime = opts.StartTime.Format(time.RFC1123)
+	uptime := int64(time.Since(opts.StartTime).Seconds())
+	data.Uptime = fmt.Sprintf("%d hr %02d min %02d sec",
+		uptime/3600, (uptime/60)%60, uptime%60)
+
+	if err := defaultTmp.Execute(wr, data); err != nil {
+		return fmt.Errorf("couldn't execute template: %v", err)
+	}
+
+	return nil
+}
+
+var defaultTmp = template.Must(template.New("").Parse(`
+<!DOCTYPE html>
+<html>
+<head>
+	<title>Status for {{.ServerName}}</title>
+		<style>
+		body {
+			font-family: sans-serif;
+		}
+		h1 {
+			clear: both;
+			width: 100%;
+			text-align: center;
+			font-size: 120%;
+			background: #eef;
+		}
+		.lefthand {
+			float: left;
+			width: 80%;
+		}
+		.righthand {
+			text-align: right;
+		}
+		td {
+		  background-color: rgba(0, 0, 0, 0.05);
+		}
+	</style>
+</head>
+
+<body>
+<h1>Status for {{.ServerName}}</h1>
+
+<div>
+	<div class=lefthand>
+		Started: {{.StartTime}}<br>
+		Up {{.Uptime}}<br>
+</body>
+</html>
+`))
diff --git a/staging/src/k8s.io/component-base/statusz/statusz.go b/staging/src/k8s.io/component-base/statusz/statusz.go
@@ -0,0 +1,82 @@
+/*
+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 statusz
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"net/http"
+	"time"
+
+	"k8s.io/apiserver/pkg/endpoints/metrics"
+	"k8s.io/klog/v2"
+)
+
+type Statusz struct {
+	registry *statuszRegistry
+}
+
+type Options struct {
+	ComponentName string
+	StartTime     time.Time
+}
+
+type mux interface {
+	Handle(path string, handler http.Handler)
+}
+
+func (f Statusz) Install(m mux, opts Options) {
+	f.registry = Register(opts)
+	f.registry.installHandler(m)
+}
+
+func (reg *statuszRegistry) installHandler(m mux) {
+	reg.lock.Lock()
+	defer reg.lock.Unlock()
+	m.Handle("/statusz",
+		metrics.InstrumentHandlerFunc("GET",
+			/* group = */ "",
+			/* version = */ "",
+			/* resource = */ "",
+			/* subresource = */ "/statusz",
+			/* scope = */ "",
+			/* component = */ "",
+			/* deprecated */ false,
+			/* removedRelease */ "",
+			handleSections(reg.sections)))
+}
+
+// handleSections returns an http.HandlerFunc that serves the provided sections.
+func handleSections(sections []section) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var individualCheckOutput bytes.Buffer
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+		w.Header().Set("X-Content-Type-Options", "nosniff")
+		for _, section := range sections {
+			err := section.Func(context.Background(), w)
+			if err != nil {
+				fmt.Fprintf(&individualCheckOutput, "[-]%s failed: reason withheld\n", section.Title)
+				klog.V(2).Infof("%s section failed: %v", section.Title, err)
+				http.Error(w, fmt.Sprintf("%s%s section failed", individualCheckOutput.String(), section.Title), http.StatusInternalServerError)
+				return
+			}
+			fmt.Fprint(w)
+		}
+		individualCheckOutput.WriteTo(w)
+	}
+}
diff --git a/staging/src/k8s.io/component-base/statusz/statusz_test.go b/staging/src/k8s.io/component-base/statusz/statusz_test.go
@@ -0,0 +1,97 @@
+/*
+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 statusz
+
+import (
+	"bytes"
+	"fmt"
+	"html/template"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+)
+
+func TestStatusz(t *testing.T) {
+	tests := []struct {
+		name             string
+		opts             Options
+		expectedTemplate *template.Template
+		expectedStatus   int
+	}{
+		{
+			name: "default",
+			opts: Options{
+				ComponentName: "test-component",
+				StartTime:     time.Now(),
+			},
+			expectedTemplate: defaultTmp,
+			expectedStatus:   http.StatusOK,
+		},
+	}
+
+	for i, test := range tests {
+		mux := http.NewServeMux()
+		Statusz{}.Install(mux, test.opts)
+
+		path := "/statusz"
+		req, err := http.NewRequest("GET", fmt.Sprintf("http://example.com%s", path), nil)
+		if err != nil {
+			t.Fatalf("case[%d] Unexpected error: %v", i, err)
+		}
+
+		w := httptest.NewRecorder()
+		mux.ServeHTTP(w, req)
+		if w.Code != test.expectedStatus {
+			t.Errorf("case[%d] Expected: %v, got: %v", i, test.expectedStatus, w.Code)
+		}
+
+		c := w.Header().Get("Content-Type")
+		if c != "text/plain; charset=utf-8" {
+			t.Errorf("case[%d] Expected: %v, got: %v", i, "text/plain", c)
+		}
+
+		data := prepareData(test.opts)
+		want := new(bytes.Buffer)
+		err = test.expectedTemplate.Execute(want, data)
+		if err != nil {
+			t.Fatalf("unexpected error while executing expected template: %v", err)
+		}
+
+		if w.Body.String() != want.String() {
+			t.Errorf("case[%d] Expected:\n%v\ngot:\n%v\n", i, test.expectedTemplate, w.Body.String())
+		}
+	}
+
+}
+
+func prepareData(opts Options) struct {
+	ServerName string
+	StartTime  string
+	Uptime     string
+} {
+	var data struct {
+		ServerName string
+		StartTime  string
+		Uptime     string
+	}
+
+	data.ServerName = opts.ComponentName
+	data.StartTime = opts.StartTime.Format(time.RFC1123)
+	uptime := int64(time.Since(opts.StartTime).Seconds())
+	data.Uptime = fmt.Sprintf("%d hr %02d min %02d sec",
+		uptime/3600, (uptime/60)%60, uptime%60)
+
+	return data
+}