Most applications read information from such files in memory & don't go back to the file all the time. With that, the concern here is not that the external file is not shared across nodes. (If that was the issue, using a network file store kind of system would resolve the issue.)
The problem is in notifying all nodes of cluster that their cache of file is invalid, and should be refreshed. To do that, you'll have to build your cluster-aware mechanism which surely isn't desirable. You shouldn't have to make your application more complex just because you want to be able to deploy it on cluster also.