Add IST0137 analysis docs (#8831)

* Add IST0137 analysis docs

* Add message define

* > small example and resolve

* > fix lint?

* > fix spelling target port

* > fix grammar nit

* > fix lint

content/en/docs/reference/config/analysis/ist0137/index.md

@@ -0,0 +1,46 @@
+---
+title: DeploymentConflictingPorts
+layout: analysis-message
+owner: istio/wg-user-experience-maintainers
+test: n/a
+---
+
+This message occurs when two services selecting the same workload with same `targetPort` but different ports.
+
+## An example
+
+Consider an Istio mesh with the following services:
+
+{{< text yaml >}}
+apiVersion: v1
+kind: Service
+metadata:
+  name: nginx-a
+spec:
+  ports:
+    - port: 8080
+      protocol: TCP
+      targetPort: 80
+  selector:
+    app: nginx
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: nginx-b
+spec:
+  ports:
+    - port: 80
+      protocol: TCP
+      targetPort: 80
+  selector:
+    app: nginx
+{{< /text >}}
+
+In this example, service `nginx-a` and service `nginx-b` select the same workload `nginx` with same `targetPort` but different ports.
+
+## How to resolve
+
+This must be fixed one of two ways. Make both services use the same `port`, or make both services use different `targetPorts`.
+
+Selecting the former option will require reconfiguring the clients of one of the services to connect to a different port. Selecting the latter option will require configuring the workload pods of one of the services to listen on the same target port as the other service.

data/analysis.yaml

@@ -371,3 +371,18 @@ messages:
     args:
       - name: annotation
         type: string
+
+  - name: "DeploymentConflictingPorts"
+    code: IST0137
+    level: Warning
+    description: "Two services selecting the same workload with same target port are MUST refer to the same port."
+    template: "This deployment %s is associated with multiple services %v using targetPort %q but different ports: %v."
+    args:
+      - name: deployment
+        type: string
+      - name: services
+        type: "[]string"
+      - name: targetPort
+        type: string
+      - name: ports
+        type: "[]int32"