I'm not sure this will work, as mentioned the file input does not work well with network paths, it has a couple of issues as mentioned in the documentation and probably many others since it is not qwll tested in network paths.
Unfortunately I do not use containers, so I do not have much experience with running Logstash on containers.
One thing that you could do is to consume the logs with a normal VM and send those logs to Kafka Topics, then use Logstash on containers to consume from those Kafka Topics, apply your filters and send to your outputs.