[cloud] ECS Service load balancer modification graceful fail (#32876)

It is not possible to modify the load balancer configuration
for ECS Service.

As it is possible to detect this, it's nicer to fail gracefully
than return AWS's less meaningful failure message.

Fix PEP8 compliance

lib/ansible/modules/cloud/amazon/ecs_service.py

@@ -334,32 +334,17 @@ class EcsServiceManager:
             deploymentConfiguration=deployment_configuration,
             placementConstraints=placement_constraints,
             placementStrategy=placement_strategy)
-        return self.jsonize(response['service'])
+        return response['service']
 
     def update_service(self, service_name, cluster_name, task_definition,
-                       load_balancers, desired_count, client_token, role, deployment_configuration):
+                       desired_count, deployment_configuration):
         response = self.ecs.update_service(
             cluster=cluster_name,
             service=service_name,
             taskDefinition=task_definition,
             desiredCount=desired_count,
             deploymentConfiguration=deployment_configuration)
-        return self.jsonize(response['service'])
-
-    def jsonize(self, service):
-        # some fields are datetime which is not JSON serializable
-        # make them strings
-        if 'deployments' in service:
-            for d in service['deployments']:
-                if 'createdAt' in d:
-                    d['createdAt'] = str(d['createdAt'])
-                if 'updatedAt' in d:
-                    d['updatedAt'] = str(d['updatedAt'])
-        if 'events' in service:
-            for e in service['events']:
-                if 'createdAt' in e:
-                    e['createdAt'] = str(e['createdAt'])
-        return service
+        return response['service']
 
     def delete_service(self, service, cluster=None):
         return self.ecs.delete_service(cluster=cluster, service=service)
@@ -414,31 +399,30 @@ def main():
         if existing and 'status' in existing and existing['status'] == "ACTIVE":
             if service_mgr.is_matching_service(module.params, existing):
                 matching = True
-                results['service'] = service_mgr.jsonize(existing)
+                results['service'] = existing
             else:
                 update = True
 
         if not matching:
             if not module.check_mode:
-                loadBalancers = module.params['load_balancers']
-                for loadBalancer in loadBalancers:
-                    if 'containerPort' in loadBalancer:
-                        loadBalancer['containerPort'] = int(loadBalancer['containerPort'])
 
                 role = module.params['role']
                 clientToken = module.params['client_token']
+                loadBalancers = module.params['load_balancers']
 
                 if update:
+                    if (existing['loadBalancers'] or []) != loadBalancers:
+                        module.fail_json(msg="It is not possible to update the load balancers of an existing service")
                     # update required
                     response = service_mgr.update_service(module.params['name'],
                                                           module.params['cluster'],
                                                           module.params['task_definition'],
-                                                          loadBalancers,
                                                           module.params['desired_count'],
-                                                          clientToken,
-                                                          role,
                                                           deploymentConfiguration)
                 else:
+                    for loadBalancer in loadBalancers:
+                        if 'containerPort' in loadBalancer:
+                            loadBalancer['containerPort'] = int(loadBalancer['containerPort'])
                     # doesn't exist. create it.
                     response = service_mgr.create_service(module.params['name'],
                                                           module.params['cluster'],