What were you trying to do that didn't work?

Podman seems to leak a lot of stuff on the filesystem, and Customer can see a lot of containers left over when they do `buildah containers`. However `podman system prune --external` doesn't work either.

`podman system reset` would indeed clear out the storage, but Cu would have to bring the system to a grinding halt which is not possible everytime and affect any podman builds in progress.

github issue - https://github.com/containers/podman/issues/23683

What is the impact of this issue to you?

Causing more downtime, and eating up more disk space.

Steps to reproduce

1. Dockerfile:
   FROM ubi8/ubi
   RUN truncate -s 10G out
   RUN sleep infinity
2. Script run.sh
   #!/usr/bin/env bash
   podman build -f Dockerfile -t podmanleaker &
   sleep 10 && kill -9 $!
3. Repeatedly running `run.sh` will increase the size of this folder and `podman system prune --external` doesn't help here.
4. $ podman --version
   podman version 4.2.0

$ podman system df
TYPE TOTAL ACTIVE SIZE RECLAIMABLE
Images 10 1 5.349GB 5.247GB (98%)
Containers 0 0 0B 0B (0%)
Local Volumes 0 0 0B 0B (0%)

$ podman unshare du -sh /tmp/containers/rootless_user/
1.1G /tmp/containers/rootless_user/

$ ./run.sh &>/dev/null

$ podman system df
TYPE TOTAL ACTIVE SIZE RECLAIMABLE
Images 10 1 5.349GB 5.247GB (98%)
Containers 0 0 0B 0B (0%)
Local Volumes 0 0 0B 0B (0%)

$ podman unshare du -sh /tmp/containers/rootless_user/overlay
1.2G /tmp/containers/rootless_user/

Expected results

Delete these leaked layers, without nuking everything.

Actual results

Space is not released even after `podman system prune --external`
$ podman system df
TYPE TOTAL ACTIVE SIZE RECLAIMABLE
Images 5 3 13.57GB 3.845GB (28%)
Containers 0 0 0B 0B (0%)
Local Volumes 0 0 0B 0B (0%)

$ podman unshare du -sh /tmp/containers/rootless_user
82G /tmp/containers/rootless_user

$ podman system prune --external
$ podman unshare du -sh /tmp/containers/rootless_user
82G /tmp/containers/rootless_user

- buildah containers does display a bunch of things (even after the prune):

$ buildah --version
buildah version 1.29.1 (image-spec 1.0.2-dev, runtime-spec 1.0.2-dev)
$ buildah containers | wc -l
23