Use pool pod controller with env informer (#2161)

Signed-off-by: Sanket Sudake sanketsudake@gmail.com

- Use informers and listers in executors
- Passing context properly in pool manager executor
- Environment updates in the pool manager would not cause updates in the deployment
- Environment update minimizing downtime
- Use replicaset controller and environment delete triggers to cleanup specialized pods

pkg/utils/informer.go

@@ -1,28 +1,26 @@
 package utils
 
 import (
-	"fmt"
+	"time"
 
-	apiv1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/selection"
 	k8sInformers "k8s.io/client-go/informers"
 	"k8s.io/client-go/kubernetes"
-	k8sCache "k8s.io/client-go/tools/cache"
 	metricsapi "k8s.io/metrics/pkg/apis/metrics"
 
 	v1 "github.com/fission/fission/pkg/apis/core/v1"
 )
 
-func GetInformerFactoryByExecutor(client *kubernetes.Clientset, executorType v1.ExecutorType) (k8sInformers.SharedInformerFactory, error) {
+func GetInformerFactoryByExecutor(client *kubernetes.Clientset, executorType v1.ExecutorType, defaultResync time.Duration) (k8sInformers.SharedInformerFactory, error) {
 	executorLabel, err := labels.NewRequirement(v1.EXECUTOR_TYPE, selection.DoubleEquals, []string{string(executorType)})
 	if err != nil {
 		return nil, err
 	}
 	labelSelector := labels.NewSelector()
 	labelSelector.Add(*executorLabel)
-	informerFactory := k8sInformers.NewSharedInformerFactoryWithOptions(client, 0,
+	informerFactory := k8sInformers.NewSharedInformerFactoryWithOptions(client, defaultResync,
 		k8sInformers.WithTweakListOptions(func(options *metav1.ListOptions) {
 			options.LabelSelector = labelSelector.String()
 		}))
@@ -47,14 +45,3 @@ func SupportedMetricsAPIVersionAvailable(discoveredAPIGroups *metav1.APIGroupLis
 	}
 	return false
 }
-
-func GetCachedItem(obj apiv1.ObjectReference, informer k8sCache.SharedIndexInformer) (item interface{}, exists bool, err error) {
-	store := informer.GetStore()
-
-	item, exists, err = store.Get(obj)
-	if err != nil || !exists {
-		item, exists, err = store.GetByKey(fmt.Sprintf("%s/%s", obj.Namespace, obj.Name))
-	}
-
-	return item, exists, err
-}