Alternative Docker Logging Export Script

Yes, if you setup log to the file, you will not be able to use docker logs command (it will return empty).
To search portion of the file it is easy to do so, but you should use different tools.
For example, to get logs for 2021-11-01, you need to filter them like this:

grep "2021-11-01" /mnt/storj/storagenode/storagenode.log

For entire month:

grep "2021-10" /mnt/storj/storagenode/storagenode.log

and so on.

To rotate your logs you can setup a logrotate: