From 39e08aa1fc8788031a02aec1ce0f9988b44fadaa Mon Sep 17 00:00:00 2001
From: Shivkumar Dudhani <shivkumar@nirmata.com>
Date: Mon, 16 Dec 2019 12:55:44 -0800
Subject: [PATCH] 76 cache invalidate (#557)

* invalidate local cache of registererd resources

* update client in initContainer

* update message
---
 cmd/initContainer/main.go |  3 ++-
 cmd/kyverno/main.go       |  5 +++--
 pkg/dclient/client.go     | 28 +++++++++++++++++++++++++++-
 3 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/cmd/initContainer/main.go b/cmd/initContainer/main.go
index 841a8c7c0d..c80f5ca792 100644
--- a/cmd/initContainer/main.go
+++ b/cmd/initContainer/main.go
@@ -7,6 +7,7 @@ import (
 	"flag"
 	"os"
 	"sync"
+	"time"
 
 	"github.com/golang/glog"
 	"github.com/nirmata/kyverno/pkg/config"
@@ -41,7 +42,7 @@ func main() {
 
 	// DYNAMIC CLIENT
 	// - client for all registered resources
-	client, err := client.NewClient(clientConfig)
+	client, err := client.NewClient(clientConfig, 10*time.Second, stopCh)
 	if err != nil {
 		glog.Fatalf("Error creating client: %v\n", err)
 	}
diff --git a/cmd/kyverno/main.go b/cmd/kyverno/main.go
index 2faae3cd60..429fc5e7fd 100644
--- a/cmd/kyverno/main.go
+++ b/cmd/kyverno/main.go
@@ -60,12 +60,13 @@ func main() {
 
 	// DYNAMIC CLIENT
 	// - client for all registered resources
-	client, err := dclient.NewClient(clientConfig)
+	// - invalidate local cache of registered resource every 10 seconds
+	client, err := dclient.NewClient(clientConfig, 10*time.Second, stopCh)
 	if err != nil {
 		glog.Fatalf("Error creating client: %v\n", err)
 	}
 	// CRD CHECK
-	// - verify if the CRD for Policy & PolicyViolation are avialalbe
+	// - verify if the CRD for Policy & PolicyViolation are available
 	if !utils.CRDInstalled(client.DiscoveryClient) {
 		glog.Fatalf("Required CRDs unavailable")
 	}
diff --git a/pkg/dclient/client.go b/pkg/dclient/client.go
index e3c6bc16c4..5a5e4082e9 100644
--- a/pkg/dclient/client.go
+++ b/pkg/dclient/client.go
@@ -36,7 +36,7 @@ type Client struct {
 }
 
 //NewClient creates new instance of client
-func NewClient(config *rest.Config) (*Client, error) {
+func NewClient(config *rest.Config, resync time.Duration, stopCh <-chan struct{}) (*Client, error) {
 	dclient, err := dynamic.NewForConfig(config)
 	if err != nil {
 		return nil, err
@@ -52,6 +52,13 @@ func NewClient(config *rest.Config) (*Client, error) {
 	}
 	// Set discovery client
 	discoveryClient := ServerPreferredResources{memory.NewMemCacheClient(kclient.Discovery())}
+	// client will invalidate registered resources cache every x seconds,
+	// As there is no way to identify if the registered resource is available or not
+	// we will be invalidating the local cache, so the next request get a fresh cache
+	// If a resource is removed then and cache is not invalidate yet, we will not detect the removal
+	// but the re-sync shall re-evaluate
+	go discoveryClient.Poll(resync, stopCh)
+
 	client.SetDiscovery(discoveryClient)
 	return &client, nil
 }
@@ -266,6 +273,25 @@ type ServerPreferredResources struct {
 	cachedClient discovery.CachedDiscoveryInterface
 }
 
+//Poll will keep invalidate the local cache
+func (c ServerPreferredResources) Poll(resync time.Duration, stopCh <-chan struct{}) {
+	// start a ticker
+	ticker := time.NewTicker(resync)
+	defer func() { ticker.Stop() }()
+	glog.Infof("Starting registered resources sync: every %d seconds", resync)
+	for {
+		select {
+		case <-stopCh:
+			glog.Info("Stopping registered resources sync")
+			return
+		case <-ticker.C:
+			// set cache as stale
+			glog.V(6).Info("invalidating local client cache for registered resources")
+			c.cachedClient.Invalidate()
+		}
+	}
+}
+
 //GetGVRFromKind get the Group Version Resource from kind
 // if kind is not found in first attempt we invalidate the cache,
 // the retry will then fetch the new registered resources and check again