added manger to keep track of go routines in the services (#2869)

- added manager to wait for all go routines to end before exit
- code refactor
- renamed Manafer to Interface and GoRoutineManager to GroupManager
- replaced some go routine calls with manager Add func
- added unit tests for manager

pkg/buildermgr/buildermgr.go

@@ -29,10 +29,11 @@ import (
 	"github.com/fission/fission/pkg/executor/util"
 	fetcherConfig "github.com/fission/fission/pkg/fetcher/config"
 	"github.com/fission/fission/pkg/utils"
+	"github.com/fission/fission/pkg/utils/manager"
 )
 
 // Start the buildermgr service.
-func Start(ctx context.Context, clientGen crd.ClientGeneratorInterface, logger *zap.Logger, storageSvcUrl string) error {
+func Start(ctx context.Context, clientGen crd.ClientGeneratorInterface, logger *zap.Logger, mgr manager.Interface, storageSvcUrl string) error {
 	bmLogger := logger.Named("builder_manager")
 
 	fissionClient, err := clientGen.GetFissionClient()
@@ -69,7 +70,7 @@ func Start(ctx context.Context, clientGen crd.ClientGeneratorInterface, logger *
 		kubernetesClient, storageSvcUrl,
 		utils.GetK8sInformersForNamespaces(kubernetesClient, time.Minute*30, fv1.Pods),
 		utils.GetInformersForNamespaces(fissionClient, time.Minute*30, fv1.PackagesResource))
-	err = pkgWatcher.Run(ctx)
+	err = pkgWatcher.Run(ctx, mgr)
 	if err != nil {
 		return err
 	}

pkg/buildermgr/pkgwatcher.go

@@ -32,6 +32,7 @@ import (
 	"github.com/fission/fission/pkg/cache"
 	"github.com/fission/fission/pkg/generated/clientset/versioned"
 	"github.com/fission/fission/pkg/utils"
+	"github.com/fission/fission/pkg/utils/manager"
 	"github.com/fission/fission/pkg/utils/metrics"
 )
 
@@ -308,8 +309,12 @@ func (pkgw *packageWatcher) packageInformerHandler(ctx context.Context) k8sCache
 	}
 }
 
-func (pkgw *packageWatcher) Run(ctx context.Context) error {
-	go metrics.ServeMetrics(ctx, "buildermgr", pkgw.logger)
+func (pkgw *packageWatcher) Run(ctx context.Context, mgr manager.Interface) error {
+
+	mgr.Add(ctx, func(ctx context.Context) {
+		metrics.ServeMetrics(ctx, "buildermgr", pkgw.logger, mgr)
+	})
+
 	for _, podInformer := range pkgw.podInformer {
 		go podInformer.Run(ctx.Done())
 	}