Support short DNS names (#41)

for the moment, Osiris only supports fully qualified DNS: `name.namespace.svc.cluster.local`
But services can also be accessed using a "short" DNS: `name.namespace`

This PR adds support for activating a deployment when a request comes with a "short" name

Author: vbehar

pkg/deployments/activator/index.go

@@ -20,8 +20,8 @@ func (a *activator) updateIndex() {
 	for _, svc := range a.services {
 		if deploymentName, ok :=
 			svc.Annotations["osiris.deislabs.io/deployment"]; ok {
-			svcDNSName :=
-				fmt.Sprintf("%s.%s.svc.cluster.local", svc.Name, svc.Namespace)
+			svcShortDNSName := fmt.Sprintf("%s.%s", svc.Name, svc.Namespace)
+			svcFullDNSName := fmt.Sprintf("%s.svc.cluster.local", svcShortDNSName)
 			// Determine the "default" ingress port. When a request arrives at the
 			// activator via an ingress conroller, the request's host header won't
 			// indicate a port. After activation is complete, the activator needs to
@@ -98,8 +98,9 @@ func (a *activator) updateIndex() {
 				}
 				// If the port is 80, also index by hostname/IP sans port number...
 				if port.Port == 80 {
-					// kube-dns name
-					appsByHost[svcDNSName] = app
+					// kube-dns names
+					appsByHost[svcShortDNSName] = app
+					appsByHost[svcFullDNSName] = app
 					// cluster IP
 					appsByHost[svc.Spec.ClusterIP] = app
 					// external IPs
@@ -128,8 +129,9 @@ func (a *activator) updateIndex() {
 				if fmt.Sprintf("%d", port.Port) == tlsDefaultPort {
 					// Now index by hostname:tls. Note that there's no point in indexing
 					// by IP:tls because SNI server name will never be an IP.
-					// kube-dns name
-					appsByHost[fmt.Sprintf("%s:tls", svcDNSName)] = app
+					// kube-dns names
+					appsByHost[fmt.Sprintf("%s:tls", svcShortDNSName)] = app
+					appsByHost[fmt.Sprintf("%s:tls", svcFullDNSName)] = app
 					// Honor all annotations of the form
 					// ^osiris\.deislabs\.io/loadBalancerHostname(?:-\d+)?$
 					for k, v := range svc.Annotations {
@@ -139,8 +141,9 @@ func (a *activator) updateIndex() {
 					}
 				}
 				// Now index by hostname/IP:port...
-				// kube-dns name
-				appsByHost[fmt.Sprintf("%s:%d", svcDNSName, port.Port)] = app
+				// kube-dns names
+				appsByHost[fmt.Sprintf("%s:%d", svcShortDNSName, port.Port)] = app
+				appsByHost[fmt.Sprintf("%s:%d", svcFullDNSName, port.Port)] = app
 				// cluster IP
 				appsByHost[fmt.Sprintf("%s:%d", svc.Spec.ClusterIP, port.Port)] = app
 				// external IPs