Set up klog to write to our custom logger

go.mod

@@ -37,4 +37,5 @@ require (
 	gopkg.in/natefinch/lumberjack.v2 v2.0.0
 	gopkg.in/square/go-jose.v2 v2.5.1
 	k8s.io/apimachinery v0.19.3
+	k8s.io/klog/v2 v2.8.0 // indirect
 )

go.sum

@@ -120,6 +120,8 @@ github.com/go-logfmt/logfmt v0.5.0/go.mod h1:wCYkCAKZfumFQihp8CzCvQ3paCTfi41vtzG
 github.com/go-logr/logr v0.1.0/go.mod h1:ixOQHD9gLJUVQQ2ZOR7zLEifBX6tGkNJF4QyIY7sIas=
 github.com/go-logr/logr v0.2.0 h1:QvGt2nLcHH0WK9orKa+ppBPAxREcH364nPUedEpK0TY=
 github.com/go-logr/logr v0.2.0/go.mod h1:z6/tIYblkpsD+a4lm/fGIIU9mZ+XfAiaFtq7xTgseGU=
+github.com/go-logr/logr v0.4.0 h1:K7/B1jt6fIBQVd4Owv2MqGQClcgf0R266+7C/QjRcLc=
+github.com/go-logr/logr v0.4.0/go.mod h1:z6/tIYblkpsD+a4lm/fGIIU9mZ+XfAiaFtq7xTgseGU=
 github.com/go-openapi/jsonpointer v0.0.0-20160704185906-46af16f9f7b1/go.mod h1:+35s3my2LFTysnkMfxsJBAMHj/DoqoB9knIWoYG/Vk0=
 github.com/go-openapi/jsonreference v0.0.0-20160704190145-13c6e3589ad9/go.mod h1:W3Z9FmVs9qj+KR4zFKmDPGiLdk1D9Rlm7cyMvf57TTg=
 github.com/go-openapi/spec v0.0.0-20160808142527-6aced65f8501/go.mod h1:J8+jY1nAiCcj+friV/PDoE1/3eeccG9LYBs0tYvLOWc=
@@ -663,6 +665,8 @@ k8s.io/klog/v2 v2.0.0/go.mod h1:PBfzABfn139FHAV07az/IF9Wp1bkk3vpT2XSJ76fSDE=
 k8s.io/klog/v2 v2.2.0/go.mod h1:Od+F08eJP+W3HUb4pSrPpgp9DGU4GzlpG/TmITuYh/Y=
 k8s.io/klog/v2 v2.4.0 h1:7+X0fUguPyrKEC4WjH8iGDg3laWgMo5tMnRTIGTTxGQ=
 k8s.io/klog/v2 v2.4.0/go.mod h1:Od+F08eJP+W3HUb4pSrPpgp9DGU4GzlpG/TmITuYh/Y=
+k8s.io/klog/v2 v2.8.0 h1:Q3gmuM9hKEjefWFFYF0Mat+YyFJvsUyYuwyNNJ5C9Ts=
+k8s.io/klog/v2 v2.8.0/go.mod h1:hy9LJ/NvuK+iVyP4Ehqva4HxZG/oXyIS3n3Jmire4Ec=
 k8s.io/kube-openapi v0.0.0-20200805222855-6aeccd4b50c6/go.mod h1:UuqjUnNftUyPE5H64/qeyjQoUZhGpeFDVdxjTeEVN2o=
 sigs.k8s.io/structured-merge-diff/v4 v4.0.1/go.mod h1:bJZC9H9iH24zzfZ/41RGcq60oK1F7G282QMXDPYydCw=
 sigs.k8s.io/yaml v1.1.0/go.mod h1:UJmg0vDUVViEyp3mgSv9WPwZCDxu4rQW1olrI1uml+o=

main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"flag"
 	"fmt"
 	"math/rand"
 	"os"
@@ -12,6 +13,7 @@ import (
 	"github.com/oauth2-proxy/oauth2-proxy/v7/pkg/logger"
 	"github.com/oauth2-proxy/oauth2-proxy/v7/pkg/validation"
 	"github.com/spf13/pflag"
+	"k8s.io/klog/v2"
 )
 
 func main() {
@@ -27,8 +29,11 @@ func main() {
 	alphaConfig := configFlagSet.String("alpha-config", "", "path to alpha config file (use at your own risk - the structure in this config file may change between minor releases)")
 	convertConfig := configFlagSet.Bool("convert-config-to-alpha", false, "if true, the proxy will load configuration as normal and convert existing configuration to the alpha config structure, and print it to stdout")
 	showVersion := configFlagSet.Bool("version", false, "print version string")
+	logLevel := configFlagSet.Int("log-level", 0, "standard logging level (higher numbers will be more verbose)")
 	configFlagSet.Parse(os.Args[1:])
 
+	configureKlog(*logLevel)
+
 	if *showVersion {
 		fmt.Printf("oauth2-proxy %s (built with %s)\n", VERSION, runtime.Version())
 		return
@@ -154,3 +159,29 @@ func printConvertedConfig(opts *options.Options) error {
 
 	return nil
 }
+
+// configureKlog congiures the klog library to write its output to the OAuth2
+// Proxy logger package. This allows us to use the interfaces but retain the
+// formatting configured by our built in logger library.
+func configureKlog(logLevel int) {
+	klogFlags := flag.NewFlagSet("klog", flag.ExitOnError)
+	klog.InitFlags(klogFlags)
+
+	// If any of the following fail, this is a programming error
+	if err := klogFlags.Lookup("logtostderr").Value.Set("false"); err != nil {
+		panic(err)
+	}
+	if err := klogFlags.Lookup("one_output").Value.Set("true"); err != nil {
+		panic(err)
+	}
+	if err := klogFlags.Lookup("skip_headers").Value.Set("true"); err != nil {
+		panic(err)
+	}
+
+	// If this fails, it's a user input error
+	if err := klogFlags.Lookup("v").Value.Set(fmt.Sprintf("%d", logLevel)); err != nil {
+		logger.Fatalf("ERROR: could not set log level: %v", err)
+	}
+	klog.SetOutput(logger.StdKlogErrorLogger)
+	klog.SetOutputBySeverity("INFO", logger.StdKlogInfoLogger)
+}

pkg/logger/klog.go

@@ -0,0 +1,29 @@
+package logger
+
+// KlogInfoLogger is used for info level log output in Klog
+type KlogInfoLogger struct {
+	logger *Logger
+}
+
+// Write is used to output klog log lines
+func (l *KlogInfoLogger) Write(data []byte) (int, error) {
+	l.logger.Output(DEFAULT, 6, string(data))
+	return len(data), nil
+}
+
+// KlogInfoLogger is used for error level log output in Klog
+type KlogErrorLogger struct {
+	logger *Logger
+}
+
+// Write is used to output klog log lines
+func (l *KlogErrorLogger) Write(data []byte) (int, error) {
+	l.logger.Output(ERROR, 6, string(data))
+	return len(data), nil
+}
+
+// StdKlogInfoLogger is an info logger using the standard logger
+var StdKlogInfoLogger = &KlogInfoLogger{logger: std}
+
+// StdKlogErrorLogger is an info logger using the standard logger
+var StdKlogErrorLogger = &KlogErrorLogger{logger: std}

pkg/logger/logger.go

@@ -149,9 +149,12 @@ func (l *Logger) formatLogMessage(calldepth int, message string) []byte {
 		panic(err)
 	}
 
-	_, err = logBuff.Write([]byte("\n"))
-	if err != nil {
-		panic(err)
+	// If the output doesn't end with a new line, add one
+	if string(logBuff.Bytes()[logBuff.Len()-1]) != "\n" {
+		_, err = logBuff.Write([]byte("\n"))
+		if err != nil {
+			panic(err)
+		}
 	}
 
 	return logBuff.Bytes()