Merge pull request kubernetes#6074 from madufresneelastic/1.26-#6035

Backport kubernetes#6035 feat: json logging support into 1.26

cluster-autoscaler/FAQ.md

@@ -29,6 +29,7 @@ this document:
   * [I'm running cluster with nodes in multiple zones for HA purposes. Is that supported by Cluster Autoscaler?](#im-running-cluster-with-nodes-in-multiple-zones-for-ha-purposes-is-that-supported-by-cluster-autoscaler)
   * [How can I monitor Cluster Autoscaler?](#how-can-i-monitor-cluster-autoscaler)
   * [How can I increase the information that the CA is logging?](#how-can-i-increase-the-information-that-the-ca-is-logging)
+  * [How can I change the log format that the CA outputs?](#how-can-i-change-the-log-format-that-the-ca-outputs)
   * [How can I see all the events from Cluster Autoscaler?](#how-can-i-see-all-events-from-cluster-autoscaler)
   * [How can I scale my cluster to just 1 node?](#how-can-i-scale-my-cluster-to-just-1-node)
   * [How can I scale a node group to 0?](#how-can-i-scale-a-node-group-to-0)
@@ -931,6 +932,20 @@ or infrastructure endpoints, then setting a value of `--v=9` will show all the i
 HTTP calls made. Be aware that using verbosity levels higher than `--v=1` will generate
 an increased amount of logs, prepare your deployments and storage accordingly.
 
+### How Can I change the log format that the CA outputs?
+
+There are 2 log format options, `text` and `json`. By default (`text`), the Cluster Autoscaler will output 
+logs in the [klog native format](https://kubernetes.io/docs/concepts/cluster-administration/system-logs/#klog-output).
+```
+I0823 17:15:11.472183   29944 main.go:569] Cluster Autoscaler 1.28.0-beta.0
+```
+
+Alternatively, adding the flag `--logging-format=json` changes the 
+[log output to json](https://kubernetes.io/docs/concepts/cluster-administration/system-logs/#klog-output).
+```
+{"ts":1692825334994.433,"caller":"cluster-autoscaler/main.go:569","msg":"Cluster Autoscaler 1.28.0-beta.0\n","v":1}
+```
+
 ### What events are emitted by CA?
 
 Whenever Cluster Autoscaler adds or removes nodes it will create events

cluster-autoscaler/go.mod

@@ -87,6 +87,7 @@ require (
 	github.com/fsnotify/fsnotify v1.6.0 // indirect
 	github.com/go-logr/logr v1.2.4 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/go-logr/zapr v1.2.3 // indirect
 	github.com/go-openapi/jsonpointer v0.19.5 // indirect
 	github.com/go-openapi/jsonreference v0.20.0 // indirect
 	github.com/go-openapi/swag v0.19.14 // indirect

cluster-autoscaler/go.sum

@@ -246,6 +246,8 @@ github.com/go-logr/logr v1.2.4 h1:g01GSCwiDw2xSZfjJ2/T9M+S6pFdcNtFYsp+Y43HYDQ=
 github.com/go-logr/logr v1.2.4/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
 github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
 github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
+github.com/go-logr/zapr v1.2.3 h1:a9vnzlIBPQBBkeaR9IuMUfmVOrQlkoC4YfPoFkX3T7A=
+github.com/go-logr/zapr v1.2.3/go.mod h1:eIauM6P8qSvTw5o2ez6UEAfGjQKrxQTl5EoK+Qa2oG4=
 github.com/go-openapi/jsonpointer v0.19.3/go.mod h1:Pl9vOtqEWErmShwVjC8pYs9cog34VGT37dQOVbmoatg=
 github.com/go-openapi/jsonpointer v0.19.5 h1:gZr+CIYByUqjcgeLXnQu2gHYQC9o73G2XUeOFYEICuY=
 github.com/go-openapi/jsonpointer v0.19.5/go.mod h1:Pl9vOtqEWErmShwVjC8pYs9cog34VGT37dQOVbmoatg=

cluster-autoscaler/main.go

@@ -62,6 +62,9 @@ import (
 	kube_flag "k8s.io/component-base/cli/flag"
 	componentbaseconfig "k8s.io/component-base/config"
 	"k8s.io/component-base/config/options"
+	"k8s.io/component-base/logs"
+	logsapi "k8s.io/component-base/logs/api/v1"
+	_ "k8s.io/component-base/logs/json/register"
 	"k8s.io/component-base/metrics/legacyregistry"
 	"k8s.io/klog/v2"
 )
@@ -483,13 +486,26 @@ func run(healthCheck *metrics.HealthCheck, debuggingSnapshotter debuggingsnapsho
 
 func main() {
 	klog.InitFlags(nil)
+	featureGate := utilfeature.DefaultMutableFeatureGate
+	loggingConfig := logsapi.NewLoggingConfiguration()
+
+	if err := logsapi.AddFeatureGates(featureGate); err != nil {
+		klog.Fatalf("Failed to add logging feature flags: %v", err)
+	}
+
+	logsapi.AddFlags(loggingConfig, pflag.CommandLine)
+	featureGate.AddFlag(pflag.CommandLine)
+	kube_flag.InitFlags()
+
+	if err := logsapi.ValidateAndApply(loggingConfig, featureGate); err != nil {
+		klog.Fatalf("Failed to validate and apply logging configuration: %v", err)
+	}
+
+	logs.InitLogs()
 
 	leaderElection := defaultLeaderElectionConfiguration()
 	leaderElection.LeaderElect = true
-
 	options.BindLeaderElectionFlags(&leaderElection, pflag.CommandLine)
-	utilfeature.DefaultMutableFeatureGate.AddFlag(pflag.CommandLine)
-	kube_flag.InitFlags()
 
 	healthCheck := metrics.NewHealthCheck(*maxInactivityTimeFlag, *maxFailingTimeFlag)