Docker mount command (mount failed: Unknown error -1)

Question

I'm trying to migrate my existing application to Docker, it mounts an image but is getting an error:

 mount failed: Unknown error -1

These are the steps:

1. Create an empty floppy image of 1.44 MB as root:

   $ /sbin/mkfs.msdos -C / 1440

2. Mount the directory:

   $ sudo mount -o loop /path/imagefile.img /media/floppy1/

3. Copy the XML file to the mounted directory:

   $ cp file.xml /media/floppy1

4. Unmount the directory:

   $ umount /media/floppy1

I installed utilities to run mkfs.msdos, when I run mount command I get the following error:

[2016-05-03 05:49:53,631: DEBUG/Worker-7] [chan 0] EOF received (0)
[2016-05-03 05:49:53,632: ERROR/Worker-7] general.send_command() stderr: [u'mount: /media/floppy1: mount failed: Unknown error -1\n']

- /usr/local/src/containers/application/volumes/log/application_1/media/:/media/floppy1

In my Dockerfile:

RUN mkdir -p /media/floppy1
VOLUME ["/media/floppy1"]

This link suggest is not supported.

Answer 1

In my docker-compose I added:

privileged: true setting.