Revert "Avoid accumulating synthetic upstreams"

This reverts commit 86672df4fa.

agent/service_manager.go

@@ -326,7 +326,7 @@ func makeConfigRequest(bd BaseDeps, addReq AddServiceRequest) *structs.ServiceCo
 		// Also if we have any upstreams defined, add them to the request so we can
 		// learn about their configs.
 		for _, us := range ns.Proxy.Upstreams {
-			if us.DestinationType == "" || us.DestinationType == structs.UpstreamDestTypeService && !us.CentrallyConfigured {
+			if us.DestinationType == "" || us.DestinationType == structs.UpstreamDestTypeService {
 				sid := us.DestinationID()
 				sid.EnterpriseMeta.Merge(&ns.EnterpriseMeta)
 				upstreams = append(upstreams, sid)
@@ -440,25 +440,14 @@ func mergeServiceConfig(defaults *structs.ServiceConfigResponse, service *struct
 	// This does not apply outside of TransparentProxy mode because in that situation every possible upstream already exists
 	// inside of ns.Proxy.Upstreams.
 	if ns.Proxy.TransparentProxy {
-		var upstreams structs.Upstreams
-
-		for _, us := range ns.Proxy.Upstreams {
-			if _, ok := remoteUpstreams[us.DestinationID()]; !ok && us.CentrallyConfigured {
-				// If a centrally configured upstream is only present locally then that means it was
-				// removed from central config and should be removed from the local list as well.
-				continue
-			}
-			upstreams = append(upstreams, us)
-		}
-
 		for id, remote := range remoteUpstreams {
 			if _, ok := localUpstreams[id]; ok {
 				// Remote upstream is already present locally
 				continue
 			}
-			upstreams = append(upstreams, remote)
+
+			ns.Proxy.Upstreams = append(ns.Proxy.Upstreams, remote)
 		}
-		ns.Proxy.Upstreams = upstreams
 	}
 
 	return ns, err

agent/service_manager_test.go

@@ -1047,64 +1047,6 @@ func Test_mergeServiceConfig_UpstreamOverrides(t *testing.T) {
 				},
 			},
 		},
-		{
-			name: "synthetic local upstream is cleaned up if not in config response",
-			args: args{
-				defaults: &structs.ServiceConfigResponse{
-					UpstreamIDConfigs: structs.OpaqueUpstreamConfigs{
-						{
-							Upstream: structs.ServiceID{
-								ID:             "zap",
-								EnterpriseMeta: *structs.DefaultEnterpriseMeta(),
-							},
-							Config: map[string]interface{}{
-								"protocol": "grpc",
-							},
-						},
-					},
-				},
-				service: &structs.NodeService{
-					ID:      "foo-proxy",
-					Service: "foo-proxy",
-					Proxy: structs.ConnectProxyConfig{
-						DestinationServiceName: "foo",
-						DestinationServiceID:   "foo",
-						TransparentProxy:       true,
-						Upstreams: structs.Upstreams{
-							structs.Upstream{
-								DestinationNamespace: "default",
-								DestinationName:      "zip",
-								LocalBindPort:        8080,
-								Config: map[string]interface{}{
-									"protocol": "http",
-								},
-								// Should get zip cleaned up
-								CentrallyConfigured: true,
-							},
-						},
-					},
-				},
-			},
-			want: &structs.NodeService{
-				ID:      "foo-proxy",
-				Service: "foo-proxy",
-				Proxy: structs.ConnectProxyConfig{
-					DestinationServiceName: "foo",
-					DestinationServiceID:   "foo",
-					TransparentProxy:       true,
-					Upstreams: structs.Upstreams{
-						structs.Upstream{
-							DestinationNamespace: "default",
-							DestinationName:      "zap",
-							Config: map[string]interface{}{
-								"protocol": "grpc",
-							},
-							CentrallyConfigured: true,
-						},
-					},
-				},
-			},
-		},
 		{
 			name: "upstream mode from remote defaults overrides local default",
 			args: args{