fix(appmesh): adding support with gateway route priority (#17694)

Adding the Gateway Route `Priority` support. This is not a new feature but it was missed from the implementation.

The implementation method is mimicking how Route's `Priority` is implemented: 
 - [route-spec.ts](https://github.com/aws/aws-cdk/blob/master/packages/%40aws-cdk/aws-appmesh/lib/route-spec.ts)
 - [route.ts](https://github.com/aws/aws-cdk/blob/master/packages/%40aws-cdk/aws-appmesh/lib/route.ts)

Fixes #16821

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-appmesh/lib/gateway-route-spec.ts

@@ -148,10 +148,24 @@ export interface GrpcGatewayRouteMatch {
   readonly rewriteRequestHostname?: boolean;
 }
 
+/**
+ * Base options for all gateway route specs.
+ */
+export interface CommonGatewayRouteSpecOptions {
+  /**
+   * The priority for the gateway route. When a Virtual Gateway has multiple gateway routes, gateway route match
+   * is performed in the order of specified value, where 0 is the highest priority,
+   * and first matched gateway route is selected.
+   *
+   * @default - no particular priority
+   */
+  readonly priority?: number;
+}
+
 /**
  * Properties specific for HTTP Based GatewayRoutes
  */
-export interface HttpGatewayRouteSpecOptions {
+export interface HttpGatewayRouteSpecOptions extends CommonGatewayRouteSpecOptions {
   /**
    * The criterion for determining a request match for this GatewayRoute.
    * When path match is defined, this may optionally determine the path rewrite configuration.
@@ -169,7 +183,7 @@ export interface HttpGatewayRouteSpecOptions {
 /**
  * Properties specific for a gRPC GatewayRoute
  */
-export interface GrpcGatewayRouteSpecOptions {
+export interface GrpcGatewayRouteSpecOptions extends CommonGatewayRouteSpecOptions {
   /**
    * The criterion for determining a request match for this GatewayRoute
    */
@@ -205,6 +219,15 @@ export interface GatewayRouteSpecConfig {
    * @default - no grpc spec
    */
   readonly grpcSpecConfig?: CfnGatewayRoute.GrpcGatewayRouteProperty;
+
+  /**
+   * The priority for the gateway route. When a Virtual Gateway has multiple gateway routes, gateway route match
+   * is performed in the order of specified value, where 0 is the highest priority,
+   * and first matched gateway route is selected.
+   *
+   * @default - no particular priority
+   */
+  readonly priority?: number;
 }
 
 /**
@@ -257,12 +280,14 @@ class HttpGatewayRouteSpec extends GatewayRouteSpec {
    * Type of route you are creating
    */
   readonly routeType: Protocol;
+  readonly priority?: number;
 
   constructor(options: HttpGatewayRouteSpecOptions, protocol: Protocol.HTTP | Protocol.HTTP2) {
     super();
     this.routeTarget = options.routeTarget;
     this.routeType = protocol;
     this.match = options.match;
+    this.priority = options.priority;
   }
 
   public bind(scope: Construct): GatewayRouteSpecConfig {
@@ -301,6 +326,7 @@ class HttpGatewayRouteSpec extends GatewayRouteSpec {
       },
     };
     return {
+      priority: this.priority,
       httpSpecConfig: this.routeType === Protocol.HTTP ? httpConfig : undefined,
       http2SpecConfig: this.routeType === Protocol.HTTP2 ? httpConfig : undefined,
     };
@@ -314,11 +340,13 @@ class GrpcGatewayRouteSpec extends GatewayRouteSpec {
    * The VirtualService this GatewayRoute directs traffic to
    */
   readonly routeTarget: IVirtualService;
+  readonly priority?: number;
 
   constructor(options: GrpcGatewayRouteSpecOptions) {
     super();
     this.match = options.match;
     this.routeTarget = options.routeTarget;
+    this.priority = options.priority;
   }
 
   public bind(scope: Construct): GatewayRouteSpecConfig {
@@ -349,6 +377,7 @@ class GrpcGatewayRouteSpec extends GatewayRouteSpec {
             },
         },
       },
+      priority: this.priority,
     };
   }
 }

packages/@aws-cdk/aws-appmesh/lib/gateway-route.ts

@@ -119,6 +119,7 @@ export class GatewayRoute extends cdk.Resource implements IGatewayRoute {
         httpRoute: routeSpecConfig.httpSpecConfig,
         http2Route: routeSpecConfig.http2SpecConfig,
         grpcRoute: routeSpecConfig.grpcSpecConfig,
+        priority: routeSpecConfig.priority,
       },
       virtualGatewayName: this.virtualGateway.virtualGatewayName,
     });

packages/@aws-cdk/aws-appmesh/lib/route-spec.ts

@@ -120,8 +120,8 @@ export interface GrpcRouteMatch {
  */
 export interface RouteSpecOptionsBase {
   /**
-   * The priority for the route. Routes are matched based on the specified
-   * value, where 0 is the highest priority.
+   * The priority for the route. When a Virtual Router has multiple routes, route match is performed in the
+   * order of specified value, where 0 is the highest priority, and first matched route is selected.
    *
    * @default - no particular priority
    */
@@ -357,8 +357,8 @@ export interface RouteSpecConfig {
   readonly tcpRouteSpec?: CfnRoute.TcpRouteProperty;
 
   /**
-   * The priority for the route. Routes are matched based on the specified
-   * value, where 0 is the highest priority.
+   * The priority for the route. When a Virtual Router has multiple routes, route match is performed in the
+   * order of specified value, where 0 is the highest priority, and first matched route is selected.
    *
    * @default - no particular priority
    */

packages/@aws-cdk/aws-appmesh/test/gateway-route.test.ts

@@ -1122,8 +1122,86 @@ describe('gateway route', () => {
           },
         },
       });
+    });
+  });
+
+  describe('with priority', () => {
+    test('should set the priority for http gateway route', () => {
+      // GIVEN
+      const stack = new cdk.Stack();
+
+      // WHEN
+      const mesh = new appmesh.Mesh(stack, 'mesh', {
+        meshName: 'test-mesh',
+      });
+
+      const virtualGateway = new appmesh.VirtualGateway(stack, 'gateway-1', {
+        listeners: [appmesh.VirtualGatewayListener.http()],
+        mesh: mesh,
+      });
+
+      const virtualService = new appmesh.VirtualService(stack, 'vs-1', {
+        virtualServiceProvider: appmesh.VirtualServiceProvider.none(mesh),
+        virtualServiceName: 'target.local',
+      });
+
+      // Add an HTTP Route
+      virtualGateway.addGatewayRoute('gateway-http-route', {
+        routeSpec: appmesh.GatewayRouteSpec.http({
+          routeTarget: virtualService,
+          match: {
+          },
+          priority: 100,
+        }),
+        gatewayRouteName: 'gateway-http-route',
+      });
+
+      // THEN
+      expect(stack).toHaveResourceLike('AWS::AppMesh::GatewayRoute', {
+        Spec: {
+          Priority: 100,
+        },
+      });
+    });
 
+    test('should set the priority for grpc gateway route', () => {
+      // GIVEN
+      const stack = new cdk.Stack();
 
+      // WHEN
+      const mesh = new appmesh.Mesh(stack, 'mesh', {
+        meshName: 'test-mesh',
+      });
+
+      const virtualGateway = new appmesh.VirtualGateway(stack, 'gateway-1', {
+        listeners: [appmesh.VirtualGatewayListener.grpc()],
+        mesh: mesh,
+      });
+
+      const virtualService = new appmesh.VirtualService(stack, 'vs-1', {
+        virtualServiceProvider: appmesh.VirtualServiceProvider.none(mesh),
+        virtualServiceName: 'target.local',
+      });
+
+      // Add an Grpc Route
+      new appmesh.GatewayRoute(stack, 'test-node', {
+        routeSpec: appmesh.GatewayRouteSpec.grpc({
+          match: {
+            serviceName: virtualService.virtualServiceName,
+          },
+          routeTarget: virtualService,
+          priority: 500,
+        }),
+        virtualGateway: virtualGateway,
+        gatewayRouteName: 'routeWithPriority',
+      });
+
+      // THEN
+      expect(stack).toHaveResourceLike('AWS::AppMesh::GatewayRoute', {
+        Spec: {
+          Priority: 500,
+        },
+      });
     });
   });