If you want to use Chunked Uploads behind load balancers that is not configured to use sticky sessions you'll eventually end up with a bunch of chunks on every instance and the bundle is not able to reassemble the file on the server.
You can avoid this problem by using Gaufrette as an abstract filesystem. Check the following configuration as an example.
knp_gaufrette:
adapters:
gallery:
local:
directory: %kernel.root_dir%/../web/uploads
create: true
filesystems:
gallery:
adapter: gallery
stream_wrapper: ~
oneup_uploader:
chunks:
storage:
type: gaufrette
filesystem: gaufrette.gallery_filesystem
stream_wrapper: gaufrette://gallery/
mappings:
gallery:
frontend: fineuploader
storage:
type: gaufrette
filesystem: gaufrette.gallery_filesystem❗ Event though it is possible to use two different Gaufrette filesystems - one for the the chunk storage - and one for the mapping, it is not recommended.
❗ Do not use a Gaufrette filesystem for the chunk storage and a local filesystem one for the mapping. This is not possible to check during configuration and will throw unexpected errors!
Using Gaufrette filesystems for chunked upload directories has some limitations. It is highly recommended to use a Local Gaufrette adapter as it is the only one that is able to rename a file but move it. Especially when working with bigger files this can have serious perfomance advantages as this way the file doesn't have to be moved entirely to memory!