1.5 KiB
LinuxKit losetup
Image to setup a loop device backed by a regular file in a linuxkit-generated image. The typical use case is to have a portable storage location which can be used to persist settings or other files. Can be combined with the linuxkit/dm-crypt package for protection.
Usage
The setup is a one time step during boot:
onboot:
- name: losetup
image: linuxkit/losetup:<hash>
command: ["/usr/bin/loopy", "-c", "/var/test.img"]
The above will associate the file /var/test.img with /dev/loop0 and will also create it if it's not present.
The container by default bind-mounts /var:/var and /dev:/dev. Usually the loop-file will reside on external storage which should be typically mounted under /var hence the choice of the defaults. If the loop-file is located somewhere else and you need a different bind-mount for it then do not forget to explicitly bind-mount /dev:/dev as well or else losetup will fail.
Options
| Option | Default | Required | Notes |
|---|---|---|---|
-c or --create |
No | Creates the file if not present. If --create is not specified and the file is missing then the loop setup will obviously fail. |
|
-s or --size |
10 | No | If --create was specified and the file is not present then this sets the size in MiB of the created file. The file will be filled from /dev/zero. |
-d or --dev |
/dev/loop0 |
No | Loop device which should be associated with the file. |
<file> |
Yes | The file to use as backing storage. |