k8s Ingress: fix crash on rules with nil http

pkg/provider/kubernetes/ingress/fixtures/Ingress-one-rule-host-only_ingress.yml

@@ -0,0 +1,9 @@
+kind: Ingress
+apiVersion: extensions/v1beta1
+metadata:
+  name: ""
+  namespace: testing
+
+spec:
+  rules:
+  - host: testing.example.com

pkg/provider/kubernetes/ingress/kubernetes.go

@@ -313,12 +313,14 @@ func (p *Provider) loadConfigurationFromIngresses(ctx context.Context, client Cl
 				conf.HTTP.Services["default-backend"] = service
 			}
 		}
+
 		for _, rule := range ingress.Spec.Rules {
 			if err := checkStringQuoteValidity(rule.Host); err != nil {
 				log.FromContext(ctx).Errorf("Invalid syntax for host: %s", rule.Host)
 				continue
 			}
 
+			if rule.HTTP != nil {
 				for _, p := range rule.HTTP.Paths {
 					service, err := loadService(client, ingress.Namespace, p.Backend)
 					if err != nil {
@@ -360,6 +362,8 @@ func (p *Provider) loadConfigurationFromIngresses(ctx context.Context, client Cl
 					}
 					conf.HTTP.Services[serviceName] = service
 				}
+			}
+
 			err := p.updateIngressStatus(ingress, client)
 			if err != nil {
 				log.FromContext(ctx).Errorf("Error while updating ingress status: %v", err)

pkg/provider/kubernetes/ingress/kubernetes_test.go

@@ -38,6 +38,17 @@ func TestLoadConfigurationFromIngresses(t *testing.T) {
 				},
 			},
 		},
+		{
+			desc: "Ingress one rule host only",
+			expected: &dynamic.Configuration{
+				TCP: &dynamic.TCPConfiguration{},
+				HTTP: &dynamic.HTTPConfiguration{
+					Routers:     map[string]*dynamic.Router{},
+					Middlewares: map[string]*dynamic.Middleware{},
+					Services:    map[string]*dynamic.Service{},
+				},
+			},
+		},
 		{
 			desc: "Ingress with a basic rule on one path",
 			expected: &dynamic.Configuration{