Passthrough autopilot - Adds an AutopilotPassthroughPort Feature Gate…

… and new pod label (#3809)

Towards supporting Passthrough on Autopilot

install/helm/agones/defaultfeaturegates.yaml

@@ -24,6 +24,7 @@ PlayerAllocationFilter: false
 PlayerTracking: false
 
 # Dev features
+FeatureAutopilotPassthroughPort: true
 
 # Example feature
 Example: false

pkg/apis/agones/v1/gameserver.go

@@ -123,6 +123,9 @@ const (
 	// GameServerPodLabel is the label that the name of the GameServer
 	// is set on the Pod the GameServer controls
 	GameServerPodLabel = agones.GroupName + "/gameserver"
+	// GameServerPortPolicyPodLabel is the label to identify the port policy
+	// of the pod
+	GameServerPortPolicyPodLabel = agones.GroupName + "/port"
 	// GameServerContainerAnnotation is the annotation that stores
 	// which container is the container that runs the dedicated game server
 	GameServerContainerAnnotation = agones.GroupName + "/container"

pkg/cloudproduct/gke/gke.go

@@ -155,11 +155,21 @@ func (*gkeAutopilot) ValidateScheduling(ss apis.SchedulingStrategy, fldPath *fie
 }
 
 func (*gkeAutopilot) MutateGameServerPod(gss *agonesv1.GameServerSpec, pod *corev1.Pod) error {
+	setPassthroughLabel(gss, pod)
 	setPrimaryContainer(pod, gss.Container)
 	podSpecSeccompUnconfined(&pod.Spec)
 	return nil
 }
 
+// setPassthroughLabel sets the agones.dev/port: "autopilot-passthrough" label to the game server container.
+// This will help to back the container port from the allocated port using an objectSelector of this label
+// in GameServers that are using Passthrough Port Policy
+func setPassthroughLabel(gs *agonesv1.GameServerSpec, pod *corev1.Pod) {
+	if runtime.FeatureEnabled(runtime.FeatureAutopilotPassthroughPort) && hasPortPolicy(gs, agonesv1.Passthrough) {
+		pod.ObjectMeta.Labels[agonesv1.GameServerPortPolicyPodLabel] = "autopilot-passthrough"
+	}
+}
+
 // setPrimaryContainer sets the autopilot.gke.io/primary-container annotation to the game server container.
 // This acts as a hint to Autopilot for which container to add resources to during resource adjustment.
 // See https://cloud.google.com/kubernetes-engine/docs/concepts/autopilot-resource-requests#autopilot-resource-management
@@ -223,6 +233,15 @@ func setEvictionNoExtended(ev *agonesv1.Eviction, pod *corev1.Pod) error {
 	return nil
 }
 
+func hasPortPolicy(gs *agonesv1.GameServerSpec, portPolicy agonesv1.PortPolicy) bool {
+	for _, p := range gs.Ports {
+		if p.PortPolicy == portPolicy {
+			return true
+		}
+	}
+	return false
+}
+
 type autopilotPortAllocator struct {
 	minPort int32
 	maxPort int32

pkg/cloudproduct/gke/gke_test.go

@@ -14,10 +14,12 @@
 package gke
 
 import (
+	"fmt"
 	"testing"
 
 	"agones.dev/agones/pkg/apis"
 	agonesv1 "agones.dev/agones/pkg/apis/agones/v1"
+	"agones.dev/agones/pkg/util/runtime"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	corev1 "k8s.io/api/core/v1"
@@ -222,6 +224,100 @@ func TestPodSeccompUnconfined(t *testing.T) {
 	}
 }
 
+func TestSetPassthroughLabel(t *testing.T) {
+	for name, tc := range map[string]struct {
+		pod      *corev1.Pod
+		wantPod  *corev1.Pod
+		ports    []agonesv1.GameServerPort
+		features string
+	}{
+		"gameserver with with Passthrough port policy adds label to pod": {
+			features: fmt.Sprintf("%s=true", runtime.FeatureAutopilotPassthroughPort),
+
+			pod: &corev1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{},
+					Labels:      map[string]string{},
+				},
+			},
+			ports: []agonesv1.GameServerPort{
+				{
+					Name:          "awesome-udp",
+					PortPolicy:    agonesv1.Passthrough,
+					ContainerPort: 1234,
+					Protocol:      corev1.ProtocolUDP,
+				},
+			},
+			wantPod: &corev1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{},
+					Labels: map[string]string{
+						agonesv1.GameServerPortPolicyPodLabel: "autopilot-passthrough",
+					},
+				},
+			},
+		},
+		"gameserver with  Static port policy does not add label to pod": {
+			features: fmt.Sprintf("%s=true", runtime.FeatureAutopilotPassthroughPort),
+
+			pod: &corev1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{},
+					Labels:      map[string]string{},
+				},
+			},
+			ports: []agonesv1.GameServerPort{
+				{
+					Name:          "awesome-udp",
+					PortPolicy:    agonesv1.Static,
+					ContainerPort: 1234,
+					Protocol:      corev1.ProtocolUDP,
+				},
+			},
+			wantPod: &corev1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{},
+					Labels:      map[string]string{},
+				},
+			},
+		},
+		"gameserver, no feature gate, with Passthrough port policy does not add label to pod": {
+			features: fmt.Sprintf("%s=false", runtime.FeatureAutopilotPassthroughPort),
+
+			pod: &corev1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{},
+					Labels:      map[string]string{},
+				},
+			},
+			ports: []agonesv1.GameServerPort{
+				{
+					Name:          "awesome-udp",
+					PortPolicy:    agonesv1.Passthrough,
+					ContainerPort: 1234,
+					Protocol:      corev1.ProtocolUDP,
+				},
+			},
+			wantPod: &corev1.Pod{
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: map[string]string{},
+					Labels:      map[string]string{},
+				},
+			},
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			runtime.FeatureTestMutex.Lock()
+			defer runtime.FeatureTestMutex.Unlock()
+			require.NoError(t, runtime.ParseFeatures(tc.features))
+			gs := (&autopilotPortAllocator{minPort: 7000, maxPort: 8000}).Allocate(&agonesv1.GameServer{Spec: agonesv1.GameServerSpec{Ports: tc.ports}})
+			pod := tc.pod.DeepCopy()
+			setPassthroughLabel(&gs.Spec, pod)
+			assert.Equal(t, tc.wantPod, pod)
+		})
+	}
+}
+
 func TestSetEvictionNoExtended(t *testing.T) {
 	emptyPodAnd := func(f func(*corev1.Pod)) *corev1.Pod {
 		pod := &corev1.Pod{

pkg/util/runtime/features.go

@@ -58,6 +58,9 @@ const (
 	////////////////
 	// Dev features
 
+	// FeatureAutopilotPassthroughPort is a feature flag that enables/disables Passthrough Port Policy.
+	FeatureAutopilotPassthroughPort Feature = "PassthroughPortPolicy"
+
 	////////////////
 	// Example feature
 
@@ -109,6 +112,7 @@ var (
 		FeaturePlayerTracking:                   false,
 
 		// Dev features
+		FeatureAutopilotPassthroughPort: true,
 
 		// Example feature
 		FeatureExample: false,