feat: implement structured logging and remove glog

This commit uses logrus to implement structured logging throughout the
repository.

Two new flags have been introduced for managing logging: `--log-level`
and `--log-format`.

Fix #712
Fix #506

cli/ingress-controller/flag_test.go

@@ -130,6 +130,9 @@ func TestDefaults(t *testing.T) {
 		APIServerHost:      "",
 		KubeConfigFilePath: "",
 
+		LogLevel:  "info",
+		LogFormat: "text",
+
 		EnableProfiling: true,
 
 		ShowVersion:      false,
@@ -179,6 +182,8 @@ func TestOverrideViaCLIFlags(t *testing.T) {
 		"--apiserver-host", "kube-apiserver.internal",
 		"--kubeconfig", "/path/to/kubeconfig",
 
+		"--log-format", "json",
+
 		"--profiling=false",
 		"--version",
 		"--anonymous-reports=false",
@@ -216,6 +221,9 @@ func TestOverrideViaCLIFlags(t *testing.T) {
 		APIServerHost:      "kube-apiserver.internal",
 		KubeConfigFilePath: "/path/to/kubeconfig",
 
+		LogLevel:  "info",
+		LogFormat: "json",
+
 		EnableProfiling:  false,
 		ShowVersion:      true,
 		AnonymousReports: false,
@@ -240,6 +248,8 @@ func TestOverrideViaEnvVars(t *testing.T) {
 		"CONTROLLER_KONG_ADMIN_CONCURRENCY":      "100",
 		"CONTROLLER_KONG_ADMIN_TOKEN":            "my-secret-token",
 
+		"CONTROLLER_LOG_LEVEL": "panic",
+
 		"CONTROLLER_KONG_CUSTOM_ENTITIES_SECRET": "foons/barsecretname",
 	}
 	for k, v := range envs {
@@ -280,6 +290,9 @@ func TestOverrideViaEnvVars(t *testing.T) {
 		APIServerHost:      "",
 		KubeConfigFilePath: "",
 
+		LogLevel:  "panic",
+		LogFormat: "text",
+
 		EnableProfiling: true,
 
 		ShowVersion:      false,
@@ -336,6 +349,9 @@ func TestDeprecatedFlags(t *testing.T) {
 		APIServerHost:      "",
 		KubeConfigFilePath: "",
 
+		LogLevel:  "info",
+		LogFormat: "text",
+
 		EnableProfiling: true,
 
 		ShowVersion:      false,
@@ -397,6 +413,9 @@ func TestDeprecatedFlagPrecedences(t *testing.T) {
 		APIServerHost:      "",
 		KubeConfigFilePath: "",
 
+		LogLevel:  "info",
+		LogFormat: "text",
+
 		EnableProfiling: true,
 
 		ShowVersion:      false,

cli/ingress-controller/flags.go

@@ -22,7 +22,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/golang/glog"
 	"github.com/spf13/pflag"
 	"github.com/spf13/viper"
 
@@ -75,6 +74,10 @@ type cliConfig struct {
 	SyncRateLimit     float32
 	EnableReverseSync bool
 
+	// Logging
+	LogLevel  string
+	LogFormat string
+
 	// k8s connection details
 	APIServerHost      string
 	KubeConfigFilePath string
@@ -205,6 +208,14 @@ IP/hostname when the controller is being stopped.`)
 		`Define the sync frequency upper limit`)
 	flag.Bool("enable-reverse-sync", false, `Enable reverse checks from Kong to Kubernetes`)
 
+	// Logging
+	flags.String("log-level", "info",
+		`Level of logging for the controller. Allowed values are 
+trace, debug, info, warn, error, fatal and panic.`)
+	flags.String("log-format", "text",
+		`Format of logs of the controller. Allowed values are 
+text and json.`)
+
 	// k8s connection details
 	flags.String("apiserver-host", "",
 		`The address of the Kubernetes Apiserver to connect to in the format of 
@@ -228,11 +239,6 @@ func parseFlags() (cliConfig, error) {
 
 	flagSet := flagSet()
 
-	// glog
-	// The error is being ignored here for unit testing,
-	// this always errors out in unit tests but succeeds in e2e runs.
-	_ = flag.Set("logtostderr", "true")
-
 	flagSet.AddGoFlagSet(flag.CommandLine)
 	if err := flagSet.Parse(os.Args); err != nil {
 		return cliConfig{}, err
@@ -251,10 +257,6 @@ func parseFlags() (cliConfig, error) {
 		return cliConfig{}, err
 	}
 
-	for key, value := range viper.AllSettings() {
-		glog.V(2).Infof("FLAG: --%s=%q", key, value)
-	}
-
 	var config cliConfig
 	// Admission controller server properties
 	config.AdmissionWebhookListen = viper.GetString("admission-webhook-listen")
@@ -338,6 +340,10 @@ func parseFlags() (cliConfig, error) {
 	config.SyncRateLimit = (float32)(viper.GetFloat64("sync-rate-limit"))
 	config.EnableReverseSync = viper.GetBool("enable-reverse-sync")
 
+	// Logging
+	config.LogLevel = viper.GetString("log-level")
+	config.LogFormat = viper.GetString("log-format")
+
 	// k8s connection details
 	config.APIServerHost = viper.GetString("apiserver-host")
 	config.KubeConfigFilePath = viper.GetString("kubeconfig")