Add example showing impact on log output

staging/src/k8s.io/component-base/logs/example/README.md

@@ -0,0 +1,52 @@
+# Example
+
+This directory includes example logger setup allowing users to easily check and test impact of logging configuration. 
+
+Below we can see examples of how some features work.
+
+## Default
+
+Run:
+```console
+go run ./staging/src/k8s.io/component-base/logs/example/cmd/logger.go
+```
+
+Expected output:
+```
+I0605 22:03:07.224293 3228948 logger.go:58] Log using Infof, key: value
+I0605 22:03:07.224378 3228948 logger.go:59] "Log using InfoS" key="value"
+E0605 22:03:07.224393 3228948 logger.go:61] Log using Errorf, err: fail
+E0605 22:03:07.224402 3228948 logger.go:62] "Log using ErrorS" err="fail"
+I0605 22:03:07.224407 3228948 logger.go:64] Log message has been redacted. Log argument #0 contains: [secret-key]
+```
+
+## JSON 
+
+Run:
+```console
+go run ./staging/src/k8s.io/component-base/logs/example/cmd/logger.go --logging-format json
+```
+
+Expected output:
+```
+{"ts":1622923409719.5137,"msg":"Log using Infof, key: value\n","v":0}
+{"ts":1622923409719.5403,"msg":"Log using InfoS","v":0,"key":"value"}
+{"ts":1622923409719.6025,"msg":"Log using Errorf, err: fail\n","v":0}
+{"ts":1622923409719.6077,"msg":"Log using ErrorS","err":"fail","v":0}
+{"ts":1622923409719.6467,"msg":"Log with sensitive key, data: {\"secret\"}\n","v":0}
+```
+
+## Logging sanitization
+
+```console
+go run ./staging/src/k8s.io/component-base/logs/example/cmd/logger.go --experimental-logging-sanitization
+```
+
+Expected output:
+```
+I0605 22:04:02.019609 3229645 logger.go:58] Log using Infof, key: value
+I0605 22:04:02.019677 3229645 logger.go:59] "Log using InfoS" key="value"
+E0605 22:04:02.019698 3229645 logger.go:61] Log using Errorf, err: fail
+E0605 22:04:02.019709 3229645 logger.go:62] "Log using ErrorS" err="fail"
+I0605 22:04:02.019714 3229645 logger.go:64] Log message has been redacted. Log argument #0 contains: [secret-key]
+```

staging/src/k8s.io/component-base/logs/example/cmd/logger.go

@@ -0,0 +1,69 @@
+/*
+Copyright 2018 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 main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+
+	"k8s.io/component-base/logs"
+	"k8s.io/klog/v2"
+)
+
+func main() {
+	command := NewLoggerCommand()
+	logs.InitLogs()
+	defer logs.FlushLogs()
+
+	if err := command.Execute(); err != nil {
+		os.Exit(1)
+	}
+}
+
+func NewLoggerCommand() *cobra.Command {
+	o := logs.NewOptions()
+	cmd := &cobra.Command{
+		Run: func(cmd *cobra.Command, args []string) {
+			errs := o.Validate()
+			if len(errs) != 0 {
+				fmt.Fprintf(os.Stderr, "%v\n", errs)
+				os.Exit(1)
+			}
+			o.Apply()
+			runLogger()
+		},
+	}
+	o.AddFlags(cmd.Flags())
+	return cmd
+}
+
+func runLogger() {
+	klog.Infof("Log using Infof, key: %s", "value")
+	klog.InfoS("Log using InfoS", "key", "value")
+	err := errors.New("fail")
+	klog.Errorf("Log using Errorf, err: %v", err)
+	klog.ErrorS(err, "Log using ErrorS")
+	data := SensitiveData{Key: "secret"}
+	klog.Infof("Log with sensitive key, data: %q", data)
+}
+
+type SensitiveData struct {
+	Key string `json:"key" datapolicy:"secret-key"`
+}