Added new affinity mode for maximum session stickyness. Fixes kubernetes/ingress-nginx#4475

internal/ingress/annotations/sessionaffinity/main.go

@@ -28,6 +28,7 @@ import (
 
 const (
 	annotationAffinityType = "affinity"
+	annotationAffinityMode = "affinity-mode"
 	// If a cookie with this name exists,
 	// its value is used as an index into the list of available backends.
 	annotationAffinityCookieName = "session-cookie-name"
@@ -57,6 +58,8 @@ var (
 type Config struct {
 	// The type of affinity that will be used
 	Type string `json:"type"`
+	// The affinity mode, i.e. how sticky a session is
+	Mode string `json:"mode"`
 	Cookie
 }
 
@@ -136,6 +139,12 @@ func (a affinity) Parse(ing *networking.Ingress) (interface{}, error) {
 		at = ""
 	}
 
+	// Check the afinity mode that will be used
+	am, err := parser.GetStringAnnotation(annotationAffinityMode, ing)
+	if err != nil {
+		am = ""
+	}
+
 	switch at {
 	case "cookie":
 		cookie = a.cookieAffinityParse(ing)
@@ -146,6 +155,7 @@ func (a affinity) Parse(ing *networking.Ingress) (interface{}, error) {
 
 	return &Config{
 		Type:   at,
+		Mode:   am,
 		Cookie: *cookie,
 	}, nil
 }

internal/ingress/annotations/sessionaffinity/main_test.go

@@ -67,6 +67,7 @@ func TestIngressAffinityCookieConfig(t *testing.T) {
 
 	data := map[string]string{}
 	data[parser.GetAnnotationWithPrefix(annotationAffinityType)] = "cookie"
+	data[parser.GetAnnotationWithPrefix(annotationAffinityMode)] = "balanced"
 	data[parser.GetAnnotationWithPrefix(annotationAffinityCookieName)] = "INGRESSCOOKIE"
 	data[parser.GetAnnotationWithPrefix(annotationAffinityCookieExpires)] = "4500"
 	data[parser.GetAnnotationWithPrefix(annotationAffinityCookieMaxAge)] = "3000"
@@ -84,6 +85,10 @@ func TestIngressAffinityCookieConfig(t *testing.T) {
 		t.Errorf("expected cookie as affinity but returned %v", nginxAffinity.Type)
 	}
 
+	if nginxAffinity.Mode != "balanced" {
+		t.Errorf("expected balanced as affinity mode but returned %v", nginxAffinity.Mode)
+	}
+
 	if nginxAffinity.Cookie.Name != "INGRESSCOOKIE" {
 		t.Errorf("expected INGRESSCOOKIE as session-cookie-name but returned %v", nginxAffinity.Cookie.Name)
 	}