Auto-import from a read-only CIFS/SMB library imports nothing and fills the Docker disk

I mounted a large (500GB) CIFS/SMB network share into my Storyteller container and pointed automatic import at it. No books ever appeared in my library, but the Docker VM disk image grew from a couple of GB to over 120GB until the host ran out of space. The logs initially showed only starting watcher for collection ..., and later showed errors while Storyteller tried to modify files on the share.

Resolution: Root cause: the CIFS mount was read-only for the container's user, so Storyteller's EPUB 2 to EPUB 3 conversion could never write back to the library. Storyteller always assumes it can write and copy files inside your library, and when Node copies a file to a different filesystem where the destination already exists it first removes the destination -- that unlink fails on a read-only share, so every import dies after the EPUB has already been unzipped into temporary storage, and it is that temp churn that inflates the Docker disk image. Fix: either mount the share with write permission for the container, or set Epub 2 strategy to Skip on the Settings page so Storyteller never attempts the conversion, and pre-convert your books to EPUB 3 yourself with something like Calibre's ebook-convert before Storyteller ingests them. Storyteller can only handle EPUB 3, so anything left as EPUB 2 with the Skip strategy will simply not be ingested. Also check the import behaviour setting on the general Settings page rather than on the collection -- it applies to all auto imports, and for a large network library you want reference in place so books are not copied onto local disk.