Leader election lease tunables

Expose the leader election tunables for lease duration, renew deadline
and retry period via environment variables.

This is inspired by rabbitmq operator exposes the same.

Jira: OSPRH-16335

Author: hjensas

main.go

@@ -20,8 +20,11 @@ import (
 	"context"
 	"crypto/tls"
 	"flag"
+	"fmt"
 	"os"
+	"strconv"
 	"strings"
+	"time"
 
 	// Import all Kubernetes client auth plugins (e.g. Azure, GCP, OIDC, etc.)
 	// to ensure that exec-entrypoint and run can make use of them.
@@ -97,7 +100,7 @@ func main() {
 		c.NextProtos = []string{"http/1.1"}
 	}
 
-	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
+	options := ctrl.Options{
 		Scheme: scheme,
 		Metrics: metricsserver.Options{
 			BindAddress: metricsAddr,
@@ -110,7 +113,24 @@ func main() {
 				Port:    9443,
 				TLSOpts: []func(config *tls.Config){disableHTTP2},
 			}),
-	})
+	}
+
+	if leaseDuration := getEnvInDuration("LEASE_DURATION"); leaseDuration != 0 {
+		setupLog.Info("manager configured with lease duration", "seconds", int(leaseDuration.Seconds()))
+		options.LeaseDuration = &leaseDuration
+	}
+
+	if renewDeadline := getEnvInDuration("RENEW_DEADLINE"); renewDeadline != 0 {
+		setupLog.Info("manager configured with renew deadline", "seconds", int(renewDeadline.Seconds()))
+		options.RenewDeadline = &renewDeadline
+	}
+
+	if retryPeriod := getEnvInDuration("RETRY_PERIOD"); retryPeriod != 0 {
+		setupLog.Info("manager configured with retry period", "seconds", int(retryPeriod.Seconds()))
+		options.RetryPeriod = &retryPeriod
+	}
+
+	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), options)
 	if err != nil {
 		setupLog.Error(err, "unable to start manager")
 		os.Exit(1)
@@ -199,3 +219,15 @@ func main() {
 		os.Exit(1)
 	}
 }
+
+func getEnvInDuration(envName string) time.Duration {
+	var durationInt int64
+	if durationStr := os.Getenv(envName); durationStr != "" {
+		var err error
+		if durationInt, err = strconv.ParseInt(durationStr, 10, 64); err != nil {
+			setupLog.Error(err, fmt.Sprintf("unable to parse provided '%s'", envName))
+			os.Exit(1)
+		}
+	}
+	return time.Duration(durationInt) * time.Second
+}