[NET-7414] Reconcile PST for mesh gateway workloads on change to ComputedExportedServices (#20271)

* Reconcile ProxyStateTemplate on change to ComputedExportedServices

* gofmt changeset

---------

Co-authored-by: NiniOak <anita.akaeze@hashicorp.com>

agent/consul/testdata/v2-resource-dependencies.md

@@ -55,6 +55,7 @@ flowchart TD
   mesh/v2beta1/proxystatetemplate --> mesh/v2beta1/computedexplicitdestinations
   mesh/v2beta1/proxystatetemplate --> mesh/v2beta1/computedproxyconfiguration
   mesh/v2beta1/proxystatetemplate --> mesh/v2beta1/computedroutes
+  mesh/v2beta1/proxystatetemplate --> multicluster/v2/computedexportedservices
   mesh/v2beta1/tcproute
   multicluster/v2/computedexportedservices --> catalog/v2beta1/service
   multicluster/v2/computedexportedservices --> multicluster/v2/exportedservices

internal/mesh/internal/controllers/gatewayproxy/controller.go

@@ -9,11 +9,13 @@ import (
 	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/types/known/anypb"
 
+	"github.com/hashicorp/consul/acl"
 	"github.com/hashicorp/consul/internal/controller"
 	"github.com/hashicorp/consul/internal/controller/dependency"
 	"github.com/hashicorp/consul/internal/mesh/internal/controllers/apigateways"
 	"github.com/hashicorp/consul/internal/mesh/internal/controllers/gatewayproxy/builder"
 	"github.com/hashicorp/consul/internal/mesh/internal/controllers/gatewayproxy/fetcher"
+	"github.com/hashicorp/consul/internal/mesh/internal/controllers/gatewayproxy/mapper"
 	"github.com/hashicorp/consul/internal/mesh/internal/controllers/meshgateways"
 	"github.com/hashicorp/consul/internal/mesh/internal/controllers/sidecarproxy"
 	"github.com/hashicorp/consul/internal/mesh/internal/controllers/sidecarproxy/cache"
@@ -34,9 +36,11 @@ const (
 func Controller(cache *cache.Cache, trustDomainFetcher sidecarproxy.TrustDomainFetcher, dc string, defaultAllow bool) *controller.Controller {
 	// TODO NET-7016 Use caching functionality in NewController being implemented at time of writing
 	// TODO NET-7017 Add the host of other types we should watch
+	// TODO NET-7565: Add watch for serviceTypes across partitions
 	return controller.NewController(ControllerName, pbmesh.ProxyStateTemplateType).
 		WithWatch(pbcatalog.WorkloadType, dependency.ReplaceType(pbmesh.ProxyStateTemplateType)).
 		WithWatch(pbmesh.ComputedProxyConfigurationType, dependency.ReplaceType(pbmesh.ProxyStateTemplateType)).
+		WithWatch(pbmulticluster.ComputedExportedServicesType, mapper.AllMeshGatewayWorkloadsInPartition).
 		WithReconciler(&reconciler{
 			cache:          cache,
 			dc:             dc,
@@ -124,7 +128,9 @@ func (r *reconciler) reconcileMeshGatewayProxyState(ctx context.Context, dataFet
 	}
 
 	// This covers any incoming requests from inside my partition to services outside my partition
-	meshGateways, err := dataFetcher.FetchMeshGateways(ctx)
+	meshGateways, err := dataFetcher.FetchMeshGateways(ctx, &pbresource.Tenancy{
+		Partition: acl.WildcardPartitionName,
+	})
 	if err != nil {
 		rt.Logger.Warn("error reading the associated mesh gateways", "error", err)
 	}

internal/mesh/internal/controllers/gatewayproxy/fetcher/data_fetcher.go

@@ -7,7 +7,6 @@ import (
 	"context"
 	"fmt"
 
-	"github.com/hashicorp/consul/acl"
 	"github.com/hashicorp/consul/internal/mesh/internal/controllers/sidecarproxy/cache"
 	"github.com/hashicorp/consul/internal/mesh/internal/types"
 	"github.com/hashicorp/consul/internal/resource"
@@ -38,18 +37,13 @@ func (f *Fetcher) FetchMeshGateway(ctx context.Context, id *pbresource.ID) (*typ
 	dec, err := resource.GetDecodedResource[*pbmesh.MeshGateway](ctx, f.client, id)
 	if err != nil {
 		return nil, err
-	} else if dec == nil {
-		return nil, nil
 	}
 
 	return dec, nil
 }
 
 // FetchMeshGateways fetches all MeshGateway resources known to the local server.
-func (f *Fetcher) FetchMeshGateways(ctx context.Context) ([]*types.DecodedMeshGateway, error) {
-	tenancy := resource.DefaultClusteredTenancy()
-	tenancy.Partition = acl.WildcardPartitionName
-
+func (f *Fetcher) FetchMeshGateways(ctx context.Context, tenancy *pbresource.Tenancy) ([]*types.DecodedMeshGateway, error) {
 	dec, err := resource.ListDecodedResource[*pbmesh.MeshGateway](ctx, f.client, &pbresource.ListRequest{
 		Type:    pbmesh.MeshGatewayType,
 		Tenancy: tenancy,
@@ -69,8 +63,6 @@ func (f *Fetcher) FetchProxyStateTemplate(ctx context.Context, id *pbresource.ID
 	dec, err := resource.GetDecodedResource[*pbmesh.ProxyStateTemplate](ctx, f.client, id)
 	if err != nil {
 		return nil, err
-	} else if dec == nil {
-		return nil, nil
 	}
 
 	return dec, nil
@@ -84,8 +76,6 @@ func (f *Fetcher) FetchWorkload(ctx context.Context, id *pbresource.ID) (*types.
 	dec, err := resource.GetDecodedResource[*pbcatalog.Workload](ctx, f.client, id)
 	if err != nil {
 		return nil, err
-	} else if dec == nil {
-		return nil, nil
 	}
 
 	return dec, nil
@@ -99,8 +89,6 @@ func (f *Fetcher) FetchComputedExportedServices(ctx context.Context, id *pbresou
 	dec, err := resource.GetDecodedResource[*pbmulticluster.ComputedExportedServices](ctx, f.client, id)
 	if err != nil {
 		return nil, err
-	} else if dec == nil {
-		return nil, nil
 	}
 
 	return dec, nil
@@ -114,8 +102,17 @@ func (f *Fetcher) FetchService(ctx context.Context, id *pbresource.ID) (*types.D
 	dec, err := resource.GetDecodedResource[*pbcatalog.Service](ctx, f.client, id)
 	if err != nil {
 		return nil, err
-	} else if dec == nil {
-		return nil, nil
+	}
+
+	return dec, nil
+}
+
+func (f *Fetcher) FetchServiceEndpoints(ctx context.Context, id *pbresource.ID) (*types.DecodedServiceEndpoints, error) {
+	assertResourceType(pbcatalog.ServiceEndpointsType, id.Type)
+
+	dec, err := resource.GetDecodedResource[*pbcatalog.ServiceEndpoints](ctx, f.client, id)
+	if err != nil {
+		return nil, err
 	}
 
 	return dec, nil

internal/mesh/internal/controllers/gatewayproxy/mapper/meshgatewayworkloads.go

@@ -0,0 +1,51 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package mapper
+
+import (
+	"context"
+
+	"github.com/hashicorp/consul/internal/controller"
+	"github.com/hashicorp/consul/internal/mesh/internal/controllers/gatewayproxy/fetcher"
+	"github.com/hashicorp/consul/internal/resource"
+	pbcatalog "github.com/hashicorp/consul/proto-public/pbcatalog/v2beta1"
+	pbmesh "github.com/hashicorp/consul/proto-public/pbmesh/v2beta1"
+	"github.com/hashicorp/consul/proto-public/pbresource"
+)
+
+// AllMeshGatewayWorkloadsInPartition returns one controller.Request for each Workload
+// selected by a MeshGateway in the partition of the Resource.
+var AllMeshGatewayWorkloadsInPartition = func(ctx context.Context, rt controller.Runtime, res *pbresource.Resource) ([]controller.Request, error) {
+	fetcher := fetcher.New(rt.Client, nil)
+
+	gateways, err := fetcher.FetchMeshGateways(ctx, &pbresource.Tenancy{
+		Partition: res.Id.Tenancy.Partition,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	var requests []controller.Request
+
+	for _, gateway := range gateways {
+		endpointsID := resource.ReplaceType(pbcatalog.ServiceEndpointsType, gateway.Id)
+
+		endpoints, err := fetcher.FetchServiceEndpoints(ctx, endpointsID)
+		if err != nil {
+			continue
+		}
+
+		if endpoints == nil || endpoints.Data == nil {
+			continue
+		}
+
+		for _, endpoint := range endpoints.Data.Endpoints {
+			requests = append(requests, controller.Request{
+				ID: resource.ReplaceType(pbmesh.ProxyStateTemplateType, endpoint.TargetRef),
+			})
+		}
+	}
+
+	return requests, nil
+}