fix: gateway router should wait for accepted condition

It can take some time for changes to propagate for cloud load balancers,
so flagger should ensure the route changes are current before proceeding
with any more.

Signed-off-by: Steven Davidovitz <sdavidovitz@groq.com>

pkg/router/gateway_api.go

@@ -273,6 +273,26 @@ func (gwr *GatewayAPIRouter) GetRoutes(canary *flaggerv1.Canary) (
 		err = fmt.Errorf("HTTPRoute %s.%s get error: %w", apexSvcName, hrNamespace, err)
 		return
 	}
+
+	currentGeneration := httpRoute.GetGeneration()
+	for _, parentRef := range httpRoute.Spec.CommonRouteSpec.ParentRefs {
+		for _, parentStatus := range httpRoute.Status.Parents {
+			if !reflect.DeepEqual(parentStatus.ParentRef, parentRef) {
+				continue
+			}
+
+			for _, condition := range parentStatus.Conditions {
+				if condition.Type == string(v1.RouteConditionAccepted) && (condition.Status != metav1.ConditionTrue || condition.ObservedGeneration < currentGeneration) {
+					err = fmt.Errorf(
+						"HTTPRoute %s.%s parent %s is not ready (status: %s, observed generation: %d, current generation: %d)",
+						apexSvcName, hrNamespace, parentRef.Name, string(condition.Status), condition.ObservedGeneration, currentGeneration,
+					)
+					return 0, 0, false, err
+				}
+			}
+		}
+	}
+
 	var weightedRule *v1.HTTPRouteRule
 	for _, rule := range httpRoute.Spec.Rules {
 		// If session affinity is enabled, then we are only interested in the rule

pkg/router/gateway_api_test.go

@@ -28,6 +28,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/utils/ptr"
 
 	flaggerv1 "github.com/fluxcd/flagger/pkg/apis/flagger/v1beta1"
 	v1 "github.com/fluxcd/flagger/pkg/apis/gatewayapi/v1"
@@ -603,3 +604,106 @@ func TestGatewayAPIRouter_makeFilters_CORS(t *testing.T) {
 	// Assert MaxAge (24h = 86400 seconds)
 	assert.Equal(t, int32(86400), corsFilter.CORS.MaxAge)
 }
+
+func TestGatewayAPIRouter_GetRoutes(t *testing.T) {
+	canary := newTestGatewayAPICanary()
+	mocks := newFixture(canary)
+	router := &GatewayAPIRouter{
+		gatewayAPIClient: mocks.meshClient,
+		kubeClient:       mocks.kubeClient,
+		logger:           mocks.logger,
+	}
+
+	httpRoute := &v1.HTTPRoute{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:       "podinfo",
+			Generation: 1,
+		},
+		Spec: v1.HTTPRouteSpec{
+			Rules: []v1.HTTPRouteRule{
+				{
+					BackendRefs: []v1.HTTPBackendRef{
+						{
+							BackendRef: v1.BackendRef{
+								BackendObjectReference: v1.BackendObjectReference{
+									Name: "podinfo-canary",
+								},
+								Weight: ptr.To(int32(10)),
+							},
+						},
+						{
+							BackendRef: v1.BackendRef{
+								BackendObjectReference: v1.BackendObjectReference{
+									Name: "podinfo-primary",
+								},
+								Weight: ptr.To(int32(90)),
+							},
+						},
+					},
+				},
+			},
+			CommonRouteSpec: v1.CommonRouteSpec{
+				ParentRefs: []v1.ParentReference{
+					{
+						Name: "podinfo",
+					},
+				},
+			},
+		},
+	}
+	httpRoute, err := router.gatewayAPIClient.GatewayapiV1().HTTPRoutes("default").Create(context.TODO(), httpRoute, metav1.CreateOptions{})
+	require.NoError(t, err)
+
+	t.Run("httproute generation", func(t *testing.T) {
+		httpRoute.ObjectMeta.Generation = 5
+		httpRoute.Status.Parents = []v1.RouteParentStatus{
+			{
+				ParentRef: v1.ParentReference{
+					Name:        "podinfo",
+					SectionName: ptr.To(v1.SectionName("https")),
+				},
+				Conditions: []metav1.Condition{
+					{
+						Type:               string(v1.RouteConditionAccepted),
+						Status:             metav1.ConditionTrue,
+						ObservedGeneration: 1,
+					},
+				},
+			},
+			{
+				ParentRef: v1.ParentReference{
+					Name: "podinfo",
+				},
+				Conditions: []metav1.Condition{
+					{
+						Type:               string(v1.RouteConditionAccepted),
+						Status:             metav1.ConditionFalse,
+						ObservedGeneration: 4,
+					},
+				},
+			},
+		}
+		httpRoute, err := router.gatewayAPIClient.GatewayapiV1().HTTPRoutes("default").Update(context.TODO(), httpRoute, metav1.UpdateOptions{})
+		require.NoError(t, err)
+
+		_, _, _, err = router.GetRoutes(canary)
+		require.Error(t, err)
+
+		httpRoute.Status.Parents[1].Conditions[0].ObservedGeneration = 5
+		_, err = router.gatewayAPIClient.GatewayapiV1().HTTPRoutes("default").Update(context.TODO(), httpRoute, metav1.UpdateOptions{})
+		require.NoError(t, err)
+
+		_, _, _, err = router.GetRoutes(canary)
+		require.Error(t, err)
+
+		httpRoute.Status.Parents[1].Conditions[0].Status = metav1.ConditionTrue
+		_, err = router.gatewayAPIClient.GatewayapiV1().HTTPRoutes("default").Update(context.TODO(), httpRoute, metav1.UpdateOptions{})
+		require.NoError(t, err)
+
+		primaryWeight, canaryWeight, mirrored, err := router.GetRoutes(canary)
+		require.NoError(t, err)
+		assert.Equal(t, 90, primaryWeight)
+		assert.Equal(t, 10, canaryWeight)
+		assert.False(t, mirrored)
+	})
+}