feat(metrics): add scheduler related metrics (#2076)

Signed-off-by: Alexei Dodon <adodon@cisco.com>

pkg/api/controller.go

@@ -377,7 +377,7 @@ func (c *Controller) Shutdown() {
 }
 
 func (c *Controller) StartBackgroundTasks(reloadCtx context.Context) {
-	c.taskScheduler = scheduler.NewScheduler(c.Config, c.Log)
+	c.taskScheduler = scheduler.NewScheduler(c.Config, c.Metrics, c.Log)
 	c.taskScheduler.RunScheduler(reloadCtx)
 
 	// Enable running garbage-collect periodically for DefaultStore

pkg/api/cookiestore.go

@@ -3,6 +3,7 @@ package api
 import (
 	"context"
 	"encoding/gob"
+	"fmt"
 	"io/fs"
 	"os"
 	"path"
@@ -157,3 +158,12 @@ func (cleanTask *CleanTask) DoWork(ctx context.Context) error {
 
 	return nil
 }
+
+func (cleanTask *CleanTask) String() string {
+	return fmt.Sprintf("{Name: %s, sessions: %s}",
+		cleanTask.Name(), cleanTask.sessions)
+}
+
+func (cleanTask *CleanTask) Name() string {
+	return "SessionCleanupTask"
+}