AtLeast compares the local version to a minimum version.

LocalCopy copies a directory using rsync (with the --devices option).

Recv sets up the receiving half of the websocket to rsync (the other half set up by rsync.Send), putting the contents in the directory specified by path.

Send sets up the sending half of an rsync, to recursively send the directory pointed to by path over the websocket.

Debug controls additional debugging in rsync output.

RunWrapper is an optional function that's used to wrap rsync, useful for confinement like AppArmor.