Workdir used in --mount volume-opt=type=overlay contains root-owned directory and cannot be removed

[rijenkii]

Here's what I'm trying to do:

set -ex

lowerdir=$(mktemp -d)
upperdir=$(mktemp -d)
workdir=$(mktemp -d)
echo "Hello, world!" >$lowerdir/file

docker run \
  --rm -u $(id -u):$(id -g) \
  --mount type=volume,dst=/dir,volume-driver=local,volume-opt=type=overlay,\"volume-opt=o=lowerdir=$lowerdir,upperdir=$upperdir,workdir=$workdir\",volume-opt=device=overlay \
  busybox \
  /bin/sh -c "echo Testing testing 123 >/dir/file"

rm -r $lowerdir
rm -r $upperdir
rm -r $workdir

Script fails with:

rm: cannot remove '/tmp/tmp.7X3Z8skVly/work': Permission denied

What am I doing wrong? I have passed -u equal to current user, and I really don't want to use sudo to remove a temporary directory that I have created.