containers: prune dangling images

Previously, upgrading Podman containers with the same tag left
behind dangling images, causing overlay storage to grow and fill
disk space.

This change ensures dangling images are cleaned up using
podman image prune. The command is run without -a, so only
unreferenced images are removed. This provides safe cleanup while
preventing unnecessary overlay growth.

It's worth noting that when upgrading a container image using system
wide upgrade and reboot, then it's normal for one dangling image to be
left on the system after reboot. This is because the prune is done at
shutdown. When rebooting after upgrade the running container is still
valid and after the reboot the old container is replaced and left
dangling until the next reboot. There should be no case where more
than two image (one dangling) exists for a particular container.

Fixes #1098

Signed-off-by: Richard Alpe <[email protected]>

Author: rical

board/common/rootfs/usr/sbin/container

@@ -302,6 +302,9 @@ delete()
     log "$name: calling podman rm -vif ..."
     podman rm -vif "$name" >/dev/null 2>&1
     [ -n "$quiet" ] || log "Container $name has been removed."
+
+    cnt=$(podman image prune -f | wc -l)
+    log "Pruned $cnt image(s)"
 }
 
 waitfor()

doc/ChangeLog.md

@@ -14,6 +14,8 @@ All notable changes to the project are documented in this file.
 
 
 ### Fixes
+- containers: prune dangling images to reclaim disk space (#1098)
+
 [v25.06.0][] - 2025-07-01
 -------------------------