ngrok-operator/internal/controller/gateway/httproute_controller.go

/*
MIT License

Copyright (c) 2022 ngrok, Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

package gateway

import (
	"context"
	"errors"
	"fmt"
	"reflect"

	"github.com/go-logr/logr"
	ingressv1alpha1 "github.com/ngrok/ngrok-operator/api/ingress/v1alpha1"
	"github.com/ngrok/ngrok-operator/internal/controller"
	"github.com/ngrok/ngrok-operator/internal/util"
	"github.com/ngrok/ngrok-operator/pkg/managerdriver"
	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/tools/events"
	"k8s.io/utils/ptr"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/builder"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	"sigs.k8s.io/controller-runtime/pkg/predicate"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
	gatewayv1 "sigs.k8s.io/gateway-api/apis/v1"
)

// HTTPRouteReconciler reconciles a HTTPRoute object
type HTTPRouteReconciler struct {
	client.Client

	Log      logr.Logger
	Scheme   *runtime.Scheme
	Recorder events.EventRecorder
	Driver   *managerdriver.Driver
	// DrainState is used to check if the operator is draining.
	// If draining, non-delete reconciles are skipped to prevent new finalizers.
	DrainState controller.DrainState
}

func (r *HTTPRouteReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	log := ctrl.LoggerFrom(ctx).WithValues("HTTPRoute", req.NamespacedName)
	ctx = ctrl.LoggerInto(ctx, log)

	httproute := new(gatewayv1.HTTPRoute)
	err := r.Client.Get(ctx, req.NamespacedName, httproute)

	if apierrors.IsNotFound(err) {
		if err := r.Driver.DeleteNamedHTTPRoute(req.NamespacedName); err != nil {
			log.Error(err, "Failed to delete httproute from store")
			return ctrl.Result{}, err
		}

		return managerdriver.HandleSyncResult(r.Driver.Sync(ctx, r.Client))
	}

	if err != nil {
		return ctrl.Result{}, err
	}

	if controller.IsDelete(httproute) {
		log.Info("Deleting httproute from store")
		if err := util.RemoveAndSyncFinalizer(ctx, r.Client, httproute); err != nil {
			log.Error(err, "Failed to remove finalizer")
			return ctrl.Result{}, err
		}

		// Remove it from the store
		return ctrl.Result{}, r.Driver.DeleteHTTPRoute(httproute)
	}

	// Per the Gateway API spec, only manage routes that reference our GatewayClass.
	// If no parentRef targets an ngrok-managed Gateway, remove any previously-added
	// finalizer and skip reconciliation entirely.
	owned, err := routeReferencesNgrokGateway(ctx, r.Client, httproute.Namespace, httproute.Spec.ParentRefs)
	if err != nil {
		return ctrl.Result{}, err
	}
	if !owned {
		log.V(1).Info("HTTPRoute does not reference any ngrok-managed Gateway, skipping")
		return ctrl.Result{}, util.RemoveAndSyncFinalizer(ctx, r.Client, httproute)
	}

	// Skip non-delete reconciles during drain to prevent adding new finalizers
	if controller.IsDraining(ctx, r.DrainState) {
		log.V(1).Info("Draining, skipping non-delete reconcile")
		return ctrl.Result{}, nil
	}

	// The object is not being deleted, so register and sync finalizer
	if err := util.RegisterAndSyncFinalizer(ctx, r.Client, httproute); err != nil {
		log.Error(err, "Failed to register finalizer")
		return ctrl.Result{}, err
	}

	// Validate the HTTPRoute before updating the store
	_ = r.validateHTTPRoute(ctx, httproute)

	// Update the HTTPRoute in the store if it passes validation
	_, err = r.Driver.UpdateHTTPRoute(httproute)
	if err != nil {
		return ctrl.Result{}, err
	}

	return managerdriver.HandleSyncResult(r.Driver.Sync(ctx, r.Client))
}

// SetupWithManager sets up the controller with the Manager.
func (r *HTTPRouteReconciler) SetupWithManager(mgr ctrl.Manager) error {
	storedResources := []client.Object{
		&gatewayv1.GatewayClass{},
		&corev1.Service{},
		&ingressv1alpha1.Domain{},
	}

	builder := ctrl.NewControllerManagedBy(mgr).
		For(
			&gatewayv1.HTTPRoute{},
			builder.WithPredicates(
				predicate.Or(
					predicate.AnnotationChangedPredicate{},
					predicate.GenerationChangedPredicate{},
				),
			),
		)

	builder = builder.Watches(
		&gatewayv1.Gateway{},
		handler.EnqueueRequestsFromMapFunc(r.findHTTPRouteForGateway),
	)

	for _, obj := range storedResources {
		builder = builder.Watches(
			obj,
			managerdriver.NewControllerEventHandler(
				obj.GetObjectKind().GroupVersionKind().Kind,
				r.Driver,
				r.Client,
			),
		)
	}
	return builder.Complete(r)
}

var (
	ErrValidation        = errors.New("validation")
	ErrParentRefNotFound = errors.New("parentRefs not found")
)

func (r *HTTPRouteReconciler) validateHTTPRoute(ctx context.Context, route *gatewayv1.HTTPRoute) error {
	log := ctrl.LoggerFrom(ctx)

	parentRefsAccepted, err := r.validateRouteParentRefs(ctx, route)
	if err != nil {
		return err
	}

	// Merge our parent statuses with existing ones from other controllers,
	// rather than replacing the entire RouteStatus which would drop statuses
	// written by other gateway controllers (e.g. Istio, AWS).
	mergedParents := mergeParentStatuses(route.Status.RouteStatus.Parents, parentRefsAccepted)
	route.Status.RouteStatus = gatewayv1.RouteStatus{
		Parents: mergedParents,
	}

	err = r.Client.Status().Update(ctx, route)
	if err != nil {
		return fmt.Errorf("failed to update httproute status: %w", err)
	}

	// Check to make sure that all parentRefs have been accepted.
	// Use only the parent statuses computed by this controller
	// (parentRefsAccepted) to avoid being affected by conditions
	// written by other controllers.
	log.V(3).Info("Checking if all parentRefs have been accepted", "parents", parentRefsAccepted)
	for _, parentStatus := range parentRefsAccepted {
		for _, cond := range parentStatus.Conditions {
			if cond.Status != metav1.ConditionTrue {
				return fmt.Errorf("%w: route has not been accepted by all parentRefs", ErrValidation)
			}
		}
	}

	log.V(3).Info("All parentRefs have been accepted", "parents", parentRefsAccepted)
	return nil
}

func (r *HTTPRouteReconciler) validateRouteParentRefs(ctx context.Context, route *gatewayv1.HTTPRoute) ([]gatewayv1.RouteParentStatus, error) {
	log := ctrl.LoggerFrom(ctx)

	log.V(5).Info("Validating route parentRefs")

	if len(route.Spec.ParentRefs) == 0 {
		return nil, ErrParentRefNotFound
	}

	parentStatuses := []gatewayv1.RouteParentStatus{}

	for _, parentRef := range route.Spec.ParentRefs {
		// Only emit status for parentRefs that target a Gateway in the gateway API group.
		// ParentRefs for other groups/kinds belong to other controllers.
		if !parentRefIsGateway(parentRef) {
			log.V(5).Info("Skipping parentRef that does not reference a Gateway", "parentRef", parentRef)
			continue
		}

		parentRefName := string(parentRef.Name)
		parentRefNamespace := string(ptr.Deref(parentRef.Namespace, gatewayv1.Namespace(route.Namespace)))
		parentRefLog := log.WithValues("parentRef", types.NamespacedName{
			Name:      parentRefName,
			Namespace: parentRefNamespace,
		})

		// TODO: Get the gateway from the store to limit the number of API calls
		gw := &gatewayv1.Gateway{}
		if err := r.Client.Get(ctx, types.NamespacedName{Name: parentRefName, Namespace: parentRefNamespace}, gw); err != nil {
			if client.IgnoreNotFound(err) != nil {
				parentRefLog.Error(err, "Failed to get gateway")
				return nil, err
			}
			// Gateway not found; cannot confirm ownership, skip this parentRef.
			parentRefLog.V(5).Info("Gateway not found, skipping parentRef")
			continue
		}

		// Only emit status for parentRefs whose Gateway uses our GatewayClass.
		gwc := &gatewayv1.GatewayClass{}
		if err := r.Client.Get(ctx, client.ObjectKey{Name: string(gw.Spec.GatewayClassName)}, gwc); err != nil {
			if client.IgnoreNotFound(err) != nil {
				parentRefLog.Error(err, "Failed to get GatewayClass")
				return nil, err
			}
			continue
		}
		if !ShouldHandleGatewayClass(gwc) {
			parentRefLog.V(5).Info("GatewayClass is not managed by this controller, skipping parentRef",
				"gatewayClass", gwc.Name, "controllerName", gwc.Spec.ControllerName)
			continue
		}

		parentStatus := gatewayv1.RouteParentStatus{
			ParentRef:      parentRef,
			ControllerName: ControllerName,
			Conditions:     []metav1.Condition{},
		}

		// Find & use existing conditions for this parentRef so we preserve previous conditions.
		// Only reuse conditions from our own controller to avoid picking up another controller's state.
		for _, s := range route.Status.RouteStatus.Parents {
			if s.ControllerName != ControllerName {
				continue
			}
			if !reflect.DeepEqual(s.ParentRef, parentRef) {
				continue
			}
			parentStatus.Conditions = append([]metav1.Condition(nil), s.Conditions...)
			break
		}

		// Find the listener that matches the parentRef
		noMatchingParent := true
		for _, listener := range gw.Spec.Listeners {
			if parentRef.Port != nil && *parentRef.Port != listener.Port {
				continue
			}
			if parentRef.SectionName != nil && *parentRef.SectionName != listener.Name {
				continue
			}
			noMatchingParent = false
		}

		var reason gatewayv1.RouteConditionReason
		if noMatchingParent {
			reason = gatewayv1.RouteReasonNoMatchingParent
		} else {
			reason = gatewayv1.RouteReasonAccepted
		}

		cnd := r.newCondition(route, gatewayv1.RouteConditionAccepted, reason, "")
		meta.SetStatusCondition(&parentStatus.Conditions, cnd)
		parentStatuses = append(parentStatuses, parentStatus)
	}

	return parentStatuses, nil
}

// mergeParentStatuses merges our (ngrok) parent statuses into the existing list,
// preserving statuses from other controllers. It replaces entries with matching
// ControllerName and updates/adds our entries.
func mergeParentStatuses(existing, ours []gatewayv1.RouteParentStatus) []gatewayv1.RouteParentStatus {
	// Build result starting with existing statuses not owned by us
	result := make([]gatewayv1.RouteParentStatus, 0, len(existing)+len(ours))
	for _, e := range existing {
		if e.ControllerName == ControllerName {
			continue // will be replaced by our new statuses
		}
		result = append(result, e)
	}
	result = append(result, ours...)
	return result
}

func (r *HTTPRouteReconciler) newCondition(route *gatewayv1.HTTPRoute, t gatewayv1.RouteConditionType, reason gatewayv1.RouteConditionReason, msg string) metav1.Condition {
	status := metav1.ConditionTrue
	if reason != gatewayv1.RouteReasonAccepted && reason != gatewayv1.RouteReasonResolvedRefs {
		status = metav1.ConditionFalse
	}
	return metav1.Condition{
		Type:               string(t),
		Status:             status,
		ObservedGeneration: route.Generation,
		Reason:             string(reason),
		Message:            msg,
	}
}

func (r *HTTPRouteReconciler) findHTTPRouteForGateway(ctx context.Context, o client.Object) []reconcile.Request {
	log := r.Log

	gw, ok := o.(*gatewayv1.Gateway)
	if !ok {
		log.Error(nil, "object is not a Gateway", "object", o)
		return nil
	}

	log = log.WithValues(
		"gateway.name", gw.Name,
		"gateway.namespace", gw.Namespace,
		"gateway.gatewayClassName", gw.Spec.GatewayClassName,
	)

	gwc := &gatewayv1.GatewayClass{}
	err := r.Client.Get(ctx, client.ObjectKey{Name: string(gw.Spec.GatewayClassName)}, gwc)
	if err != nil {
		log.Error(err, "Failed to get GatewayClass", "gatewayClassName", gw.Spec.GatewayClassName)
		return nil
	}

	if !ShouldHandleGatewayClass(gwc) {
		log.V(5).Info("GatewayClass is not handled by this controller, ignoring")
		return nil
	}

	routes := &gatewayv1.HTTPRouteList{}
	err = r.Client.List(ctx, routes)
	if err != nil {
		log.Error(err, "Failed to list HTTPRoutes")
		return nil
	}

	requests := []reconcile.Request{}
	log.V(3).Info("Finding HTTPRoutes for Gateway")
	for _, route := range routes.Items {
		for _, parentRef := range route.Spec.ParentRefs {
			group := ptr.Deref(parentRef.Group, gatewayv1.GroupName)
			if group != gatewayv1.GroupName {
				log.V(5).Info("ParentRef group is not gateway.networking.k8s.io, ignoring", "group", parentRef.Group)
				continue
			}

			kind := ptr.Deref(parentRef.Kind, gatewayv1.Kind("Gateway"))
			if kind != "Gateway" {
				log.V(5).Info("ParentRef kind is not Gateway, ignoring", "kind", parentRef.Kind)
				continue
			}

			parentRefNamespace := string(ptr.Deref(parentRef.Namespace, gatewayv1.Namespace(route.Namespace)))
			if string(parentRef.Name) != gw.Name || parentRefNamespace != gw.Namespace {
				log.V(5).Info("ParentRef does not match Gateway, ignoring", "parentRef", parentRef)
				continue
			}

			requests = append(requests, reconcile.Request{
				NamespacedName: client.ObjectKey{
					Namespace: route.Namespace,
					Name:      route.Name,
				},
			})
			break // Only enqueue the route once per parentRef
		}
	}

	return requests
}