better use mustcompile and convert includedNamespacesRegex to Regexp type

Author: santinoncs

internal/config/default_config.go

@@ -1,5 +1,7 @@
 package config
 
+import "regexp"
+
 // UnpropgatedAnnotations is a list of annotations on objects that should _not_ be propagated by HNC.
 // Much like HNC itself, other systems (such as GKE Config Sync) use annotations to "claim" an
 // object - such as deleting objects it doesn't recognize. By removing these annotations on
@@ -15,4 +17,4 @@ var UnpropagatedAnnotations []string
 // This value is controlled by the --excluded-namespace command line, which may
 // be set multiple times.
 var excludedNamespaces map[string]bool
-var includedNamespacesRegex string
+var includedNamespacesRegex *regexp.Regexp

internal/config/namespace.go

@@ -10,7 +10,7 @@ func SetNamespaces(regex string, excluded ...string) {
 		regex = ".*"
 	}
 
-	includedNamespacesRegex = regex
+	includedNamespacesRegex = regexp.MustCompile("^" + regex + "$")
 
 	excludedNamespaces = make(map[string]bool)
 	for _, exn := range excluded {
@@ -25,8 +25,6 @@ func IsNamespaceIncluded(name string) bool {
 		return false
 	}
 
-	regex, _ := regexp.Compile("^" + includedNamespacesRegex + "$")
-
-	return regex.MatchString(name)
+	return includedNamespacesRegex.MatchString(name)
 
 }