Allow a 'location-modifier' annotation for regex paths

In nginx a modifier can be passed which decides how locations
will be parsed, i.e. regex or no regex.

This change allows a location modifier to be passed as an annotatione e.g. ingress.kubernetes.io/location-modifier: "~"
If no location-modifier is passed but 'rewrite-target' is provided, then a default of "*~" is assumed.

pkg/ingress/annotations/rewrite/main.go

@@ -25,6 +25,8 @@ import (
 
 const (
 	rewriteTo                      = "ingress.kubernetes.io/rewrite-target"
+	locationModifier               = "ingress.kubernetes.io/location-modifier"
+	defaultRewriteLocationModifier = "~*"
 	addBaseURL                     = "ingress.kubernetes.io/add-base-url"
 	baseURLScheme                  = "ingress.kubernetes.io/base-url-scheme"
 	sslRedirect                    = "ingress.kubernetes.io/ssl-redirect"
@@ -36,6 +38,8 @@ const (
 type Redirect struct {
 	// Target URI where the traffic must be redirected
 	Target string `json:"target"`
+	// Location modifier
+	LocationModifier string `json:"locationModifier"`
 	// AddBaseURL indicates if is required to add a base tag in the head
 	// of the responses from the upstream servers
 	AddBaseURL bool `json:"addBaseUrl"`
@@ -92,6 +96,11 @@ func NewParser(br resolver.DefaultBackend) parser.IngressAnnotation {
 // rule used to rewrite the defined paths
 func (a rewrite) Parse(ing *extensions.Ingress) (interface{}, error) {
 	rt, _ := parser.GetStringAnnotation(rewriteTo, ing)
+	locMod, _ := parser.GetStringAnnotation(locationModifier, ing)
+
+	if rt != "" && locMod == "" {
+		locMod = defaultRewriteLocationModifier
+	}
 	sslRe, err := parser.GetBoolAnnotation(sslRedirect, ing)
 	if err != nil {
 		sslRe = a.backendResolver.GetDefaultBackend().SSLRedirect
@@ -103,12 +112,16 @@ func (a rewrite) Parse(ing *extensions.Ingress) (interface{}, error) {
 	abu, _ := parser.GetBoolAnnotation(addBaseURL, ing)
 	bus, _ := parser.GetStringAnnotation(baseURLScheme, ing)
 	ar, _ := parser.GetStringAnnotation(appRoot, ing)
-	return &Redirect{
+
+	redirect := &Redirect{
 		Target:           rt,
+		LocationModifier: locMod,
 		AddBaseURL:       abu,
 		BaseURLScheme:    bus,
 		SSLRedirect:      sslRe,
 		ForceSSLRedirect: fSslRe,
 		AppRoot:          ar,
-	}, nil
+	}
+
+	return redirect, nil
 }

pkg/ingress/annotations/rewrite/main_test.go

@@ -100,6 +100,31 @@ func TestRedirect(t *testing.T) {
 	if redirect.Target != defRoute {
 		t.Errorf("Expected %v as redirect but returned %s", defRoute, redirect.Target)
 	}
+
+	if redirect.LocationModifier != defaultRewriteLocationModifier {
+		t.Errorf("Expected %v as implicit location modifier but returned %s", defaultRewriteLocationModifier, redirect.LocationModifier)
+	}
+}
+
+func TestRegex(t *testing.T) {
+	ing := buildIngress()
+
+	data := map[string]string{}
+	modifier := "~"
+	data[locationModifier] = modifier
+	ing.SetAnnotations(data)
+
+	i, err := NewParser(mockBackend{}).Parse(ing)
+	if err != nil {
+		t.Errorf("Unexpected error with ingress: %v", err)
+	}
+	redirect, ok := i.(*Redirect)
+	if !ok {
+		t.Errorf("expected a Redirect type")
+	}
+	if redirect.LocationModifier != modifier {
+		t.Errorf("Expected %v as location modifier but returned %s", modifier, redirect.LocationModifier)
+	}
 }
 
 func TestSSLRedirect(t *testing.T) {