add string split function to template funcMap

docs/user-guide/nginx-configuration/custom-template.md

@@ -30,6 +30,7 @@ In addition to the built-in functions provided by the Go package the following f
 - hasSuffix: [strings.HasSuffix](https://golang.org/pkg/strings/#HasSuffix)
 - toUpper: [strings.ToUpper](https://golang.org/pkg/strings/#ToUpper)
 - toLower: [strings.ToLower](https://golang.org/pkg/strings/#ToLower)
+- split: [strings.Split](https://golang.org/pkg/strings/#Split)
 - quote: wraps a string in double quotes
 - buildLocation: helps to build the NGINX Location section in each server
 - buildProxyPass: builds the reverse proxy configuration

internal/ingress/controller/template/template.go

@@ -152,6 +152,7 @@ var (
 		"buildDenyVariable":               buildDenyVariable,
 		"getenv":                          os.Getenv,
 		"contains":                        strings.Contains,
+		"split":                           strings.Split,
 		"hasPrefix":                       strings.HasPrefix,
 		"hasSuffix":                       strings.HasSuffix,
 		"trimSpace":                       strings.TrimSpace,