From 27c0fdee7b173094e7aa78ed94102d58c77826f5 Mon Sep 17 00:00:00 2001
From: AdheipSingh <34169002+AdheipSingh@users.noreply.github.com>
Date: Mon, 16 May 2022 14:51:55 +0530
Subject: [PATCH] Watch Multiple Namespaces (#240)

* WIP: on druid k8s extension, do, and watch ns

* support for multiple namespaces to watch

* support for multiple namespaces to watch

* fix typo

* fix identation
---
 chart/values.yaml |  2 +-
 main.go           | 22 ++++++++++++++++++++--
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/chart/values.yaml b/chart/values.yaml
index 94123674..b458685d 100644
--- a/chart/values.yaml
+++ b/chart/values.yaml
@@ -5,7 +5,7 @@
 env:
   DENY_LIST: "default,kube-system" # Comma-separated list of namespaces to ignore
   RECONCILE_WAIT: "10s"            # Reconciliation delay
-  WATCH_NAMESPACE: ""              # Namespace to watch or empty string to watch all namespaces
+  WATCH_NAMESPACE: ""              # Namespace to watch or empty string to watch all namespaces, To watch multiple namespaces add , into string. Ex: WATCH_NAMESPACE: "ns1,ns2,ns3"
 
 replicaCount: 1
 
diff --git a/main.go b/main.go
index 36555d18..efa2dae5 100644
--- a/main.go
+++ b/main.go
@@ -3,11 +3,13 @@ package main
 import (
 	"flag"
 	"os"
+	"strings"
 
 	"k8s.io/apimachinery/pkg/runtime"
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
 	_ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
 	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/cache"
 	"sigs.k8s.io/controller-runtime/pkg/healthz"
 	"sigs.k8s.io/controller-runtime/pkg/log/zap"
 
@@ -17,8 +19,9 @@ import (
 )
 
 var (
-	scheme   = runtime.NewScheme()
-	setupLog = ctrl.Log.WithName("setup")
+	scheme         = runtime.NewScheme()
+	setupLog       = ctrl.Log.WithName("setup")
+	watchNamespace = os.Getenv("WATCH_NAMESPACE")
 )
 
 func init() {
@@ -50,6 +53,7 @@ func main() {
 		LeaderElection:         enableLeaderElection,
 		LeaderElectionID:       "e6946145.apache.org",
 		Namespace:              os.Getenv("WATCH_NAMESPACE"),
+		NewCache:               watchNamespaceCache(),
 	})
 
 	if err != nil {
@@ -79,3 +83,17 @@ func main() {
 		os.Exit(1)
 	}
 }
+
+func watchNamespaceCache() cache.NewCacheFunc {
+	var managerWatchCache cache.NewCacheFunc
+	if watchNamespace != "" {
+		ns := strings.Split(watchNamespace, ",")
+		for i := range ns {
+			ns[i] = strings.TrimSpace(ns[i])
+		}
+		managerWatchCache = cache.MultiNamespacedCacheBuilder(ns)
+		return managerWatchCache
+	}
+	managerWatchCache = (cache.NewCacheFunc)(nil)
+	return managerWatchCache
+}