Update walkthrough to use frontend/backend structure

Author: sshver

walkthroughs/fargate/README.md

@@ -41,13 +41,13 @@ Log into the App Mesh console and drill down into "Virtual routers" for the mesh
 Test the service and confirm in X-Ray that the traffic flows through the `colorteller-blue` as expected with no errors.
 
 ![](../../examples/apps/colorapp/img/appmesh-xray-tracing-1.png)
-<p align="center"><b><i>Figure 5.</i></b> Tracing the colorgateway virtual node.</p>
+<p align="center"><b><i>Figure 5.</i></b> Tracing the frontend virtual node.</p>
 
 ### Deploy the new colorteller to Fargate
 
 For this configuration, we will deploy `colorteller-green`, which represents version 2 of our colorteller service. Initally, we will only send 30% of our traffic over to it. If our monitoring indicates that the service is healthy, we'll increase it to 60%, then finally to 100%. In the real world, you might choose more granular increases with automated rollout (and rollback if issues are indicated), but we're keeping things simple for the demo.
 
-As part of the original [walkthrough] we pushed the `gateway` and `colorteller` images to ECR (see [Deploy Images]) and then launched ECS tasks with these images. We will now launch an ECS task using the Fargate launch type with the same `colorteller` and `envoy` images. When the task is deployed, the running `envoy` container will be a sidecar for the `colorteller` container. Even with the Fargate launch type where we don't manually configure EC2 instances, a sidecar container will always be co-located on the same physical instance and its lifecycle coupled to the lifecycle of the primary application container (see [Sidecar Pattern]).
+As part of the original [walkthrough] we pushed the `frontend` and `colorteller` images to ECR (see [Deploy Images]) and then launched ECS tasks with these images. We will now launch an ECS task using the Fargate launch type with the same `colorteller` and `envoy` images. When the task is deployed, the running `envoy` container will be a sidecar for the `colorteller` container. Even with the Fargate launch type where we don't manually configure EC2 instances, a sidecar container will always be co-located on the same physical instance and its lifecycle coupled to the lifecycle of the primary application container (see [Sidecar Pattern]).
 
 #### 1. Update the mesh configuration
 

walkthroughs/fargate/appmesh-colorapp.yaml

@@ -195,22 +195,22 @@ Resources:
           VirtualNode:
             VirtualNodeName: tcpecho-vn
 
-  ColorGatewayVirtualNode:
+  FrontendVirtualNode:
     Type: AWS::AppMesh::VirtualNode
     DependsOn:
       - ColorTellerVirtualService
       - TcpEchoVirtualService
     Properties:
       MeshName: !Ref AppMeshMeshName
-      VirtualNodeName: colorgateway-vn
+      VirtualNodeName: frontend-vn
       Spec:
         Listeners:
           - PortMapping:
               Port: 9080
               Protocol: http
         ServiceDiscovery:
           DNS:
-            Hostname: !Sub "colorgateway.${ServicesDomain}"
+            Hostname: !Sub "frontend.${ServicesDomain}"
         Backends:
           - VirtualService:
               VirtualServiceName: !Sub "colorteller.${ServicesDomain}"