Add least time load balancing strategy

pkg/provider/kubernetes/crd/fixtures/with_leasttime_strategy.yml

@@ -0,0 +1,16 @@
+apiVersion: traefik.io/v1alpha1
+kind: IngressRoute
+metadata:
+  name: test.route
+  namespace: default
+spec:
+  entryPoints:
+    - web
+  routes:
+  - match: Host(`foo.com`) && PathPrefix(`/leasttime`)
+    kind: Rule
+    priority: 12
+    services:
+    - name: whoami2
+      port: 8080
+      strategy: leasttime

pkg/provider/kubernetes/crd/kubernetes_http.go

@@ -384,7 +384,7 @@ func (c configBuilder) buildServersLB(namespace string, svc traefikv1alpha1.Load
 	// TODO: remove this when the fake client apply default values.
 	if svc.Strategy != "" {
 		switch svc.Strategy {
-		case dynamic.BalancerStrategyWRR, dynamic.BalancerStrategyP2C, dynamic.BalancerStrategyHRW:
+		case dynamic.BalancerStrategyWRR, dynamic.BalancerStrategyP2C, dynamic.BalancerStrategyHRW, dynamic.BalancerStrategyLeastTime:
 			lb.Strategy = svc.Strategy
 
 		// Here we are just logging a warning as the default value is already applied.

pkg/provider/kubernetes/crd/kubernetes_test.go

@@ -5667,6 +5667,54 @@ func TestLoadIngressRoutes(t *testing.T) {
 				TLS: &dynamic.TLSConfiguration{},
 			},
 		},
+		{
+			desc:  "Simple Ingress Route with leasttime strategy",
+			paths: []string{"services.yml", "with_leasttime_strategy.yml"},
+			expected: &dynamic.Configuration{
+				UDP: &dynamic.UDPConfiguration{
+					Routers:  map[string]*dynamic.UDPRouter{},
+					Services: map[string]*dynamic.UDPService{},
+				},
+				TCP: &dynamic.TCPConfiguration{
+					Routers:           map[string]*dynamic.TCPRouter{},
+					Middlewares:       map[string]*dynamic.TCPMiddleware{},
+					Services:          map[string]*dynamic.TCPService{},
+					ServersTransports: map[string]*dynamic.TCPServersTransport{},
+				},
+				HTTP: &dynamic.HTTPConfiguration{
+					Routers: map[string]*dynamic.Router{
+						"default-test-route-55869f6407935ccfa805": {
+							EntryPoints: []string{"web"},
+							Service:     "default-test-route-55869f6407935ccfa805",
+							Rule:        "Host(`foo.com`) && PathPrefix(`/leasttime`)",
+							Priority:    12,
+						},
+					},
+					Middlewares: map[string]*dynamic.Middleware{},
+					Services: map[string]*dynamic.Service{
+						"default-test-route-55869f6407935ccfa805": {
+							LoadBalancer: &dynamic.ServersLoadBalancer{
+								Strategy: dynamic.BalancerStrategyLeastTime,
+								Servers: []dynamic.Server{
+									{
+										URL: "http://10.10.0.3:8080",
+									},
+									{
+										URL: "http://10.10.0.4:8080",
+									},
+								},
+								PassHostHeader: pointer(true),
+								ResponseForwarding: &dynamic.ResponseForwarding{
+									FlushInterval: ptypes.Duration(100 * time.Millisecond),
+								},
+							},
+						},
+					},
+					ServersTransports: map[string]*dynamic.ServersTransport{},
+				},
+				TLS: &dynamic.TLSConfiguration{},
+			},
+		},
 	}
 
 	for _, test := range testCases {

pkg/provider/kubernetes/crd/traefikio/v1alpha1/ingressroute.go

@@ -118,10 +118,10 @@ type LoadBalancerSpec struct {
 	// It defaults to https when Kubernetes Service port is 443, http otherwise.
 	Scheme string `json:"scheme,omitempty"`
 	// Strategy defines the load balancing strategy between the servers.
-	// Supported values are: wrr (Weighed round-robin), p2c (Power of two choices), and hrw (Highest Random Weight).
+	// Supported values are: wrr (Weighed round-robin), p2c (Power of two choices), hrw (Highest Random Weight), and leasttime (Least-Time).
 	// RoundRobin value is deprecated and supported for backward compatibility.
-	// TODO: when the deprecated RoundRobin value will be removed, set the default value to wrr.
-	// +kubebuilder:validation:Enum=wrr;p2c;hrw;RoundRobin
+	// TODO: when the deprecated RoundRobin value will be removed, set the default kubebuilder value to wrr.
+	// +kubebuilder:validation:Enum=wrr;p2c;hrw;leasttime;RoundRobin
 	Strategy dynamic.BalancerStrategy `json:"strategy,omitempty"`
 	// PassHostHeader defines whether the client Host header is forwarded to the upstream Kubernetes Service.
 	// By default, passHostHeader is true.