Add Dockerfile

[martenjacobs]

This Dockerfile makes it easy to run fstransform under Docker.

docker build . -t fstransform

Usage is then simply:

docker run -it --privileged --rm fstransform [ARGS]

I tested it using the following:

docker run -it --rm --privileged -v "fstransform-work:/app/work" --entrypoint bash fstransform

Then from inside the docker container:

dd if=/dev/zero of=disk.img bs=1M count=100
losetup -fP disk.img
losetup -a
mkfs.xfs /dev/loop0
mkdir -p /mnt/loop
mount -t xfs /dev/loop0 /mnt/loop
dd if=/dev/zero of=/mnt/loop/file-1 bs=1M count=10
dd if=/dev/zero of=/mnt/loop/file-2 bs=1M count=20
dd if=/dev/zero of=/mnt/loop/file-3 bs=1M count=30
fstransform /dev/loop0 ext4

To clean up:

umount /mnt/loop
losetup -d /dev/loop0

[cosmos72]

I am not expert with docker - how do you access external devices/filesystems from inside it?

I am asking because if a docker installation of fstransform can only access devices/filesystems inside the docker container,
it would have limited usefulness in my opinion.

Maybe a user can merge the docker image of fstranform with other docker images, i.e. it's a way to install fstransform inside the docker image of any other software?

[martenjacobs]

I am not expert with docker - how do you access external devices/filesystems from inside it?

I am asking because if a docker installation of fstransform can only access devices/filesystems inside the docker container, it would have limited usefulness in my opinion.

Maybe a user can merge the docker image of fstranform with other docker images, i.e. it's a way to install fstransform inside the docker image of any other software?

When using --privileged you can access all the device nodes from the main system (i.e. the loop device used in my example is actually a loop device on the Docker Desktop VM). So I can just use other devices, like /dev/sda1 from inside the container.

My example was just made to be nice and self-contained.