Validate service operation prior to running

Looks like this was dropped in the last refactoring. Next step is to
separate out the command layer from the operation layer and to properly
test both. For now I'm releasing a hotfix.

- Fix display of CPU units and MiB in confirmation message

cmd/service_update.go

@@ -36,7 +36,7 @@ func (o *ServiceUpdateOperation) Validate() {
 	err := validateCpuAndMemory(o.Cpu, o.Memory)
 
 	if err != nil {
-		console.ErrorExit(err, "Invalid settings: %d CPU units / %d MiB", o.Cpu, o.Memory)
+		console.ErrorExit(err, "Invalid settings: %s CPU units / %s MiB", o.Cpu, o.Memory)
 	}
 }
 
@@ -72,6 +72,8 @@ At least one of --cpu or --memory must be specified.`,
 			Memory:      flagServiceUpdateMemory,
 		}
 
+		operation.Validate()
+
 		updateService(operation)
 	},
 }
@@ -93,5 +95,5 @@ func updateService(operation *ServiceUpdateOperation) {
 	)
 
 	ecs.UpdateServiceTaskDefinition(operation.ServiceName, newTaskDefinitionArn)
-	console.Info("Updated service %s to %d CPU units / %d MiB", operation.ServiceName, operation.Cpu, operation.Memory)
+	console.Info("Updated service %s to %s CPU units / %s MiB", operation.ServiceName, operation.Cpu, operation.Memory)
 }