discovery/kubernetes/ingress: fix scheme discovery (Closes #4327)

Signed-off-by: Dmitry Bashkatov <dbashkatov@gmail.com>

discovery/kubernetes/ingress.go

@@ -176,13 +176,24 @@ func (s *Ingress) buildIngress(ingress *v1beta1.Ingress) *targetgroup.Group {
 	}
 	tg.Labels = ingressLabels(ingress)
 
-	schema := "http"
+	tlsHosts := make(map[string]struct{})
 	if ingress.Spec.TLS != nil {
-		schema = "https"
+		for _, tls := range ingress.Spec.TLS {
+			for _, host := range tls.Hosts {
+				tlsHosts[host] = struct{}{}
 			}
+		}
+	}
+
 	for _, rule := range ingress.Spec.Rules {
 		paths := pathsFromIngressRule(&rule.IngressRuleValue)
 
+		schema := "http"
+		_, isTLS := tlsHosts[rule.Host]
+		if isTLS {
+			schema = "https"
+		}
+
 		for _, path := range paths {
 			tg.Targets = append(tg.Targets, model.LabelSet{
 				model.AddressLabel: lv(rule.Host),