Use transient mode in podman.

files/podman-clean-transient.service

@@ -0,0 +1,20 @@
+# This service runs once each boot to remove potential leftover
+# container state from previous boots.
+
+# This is needed as we're using transient mode in podman where the
+# database and other configs are stored in tmpfs, but some other files
+# are not. If we don't run this after ane unclean boot then there may
+# be leftover files that collect over time.
+
+[Unit]
+Description=Clean up podman transient data
+RequiresMountsFor=%t/containers
+Requires=boot-complete.target
+After=local-fs.target boot-complete.target
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/podman system prune --external
+
+[Install]
+WantedBy=multi-user.target

files/storage.conf

@@ -3,6 +3,11 @@
 driver = "overlay"
 runroot = "/run/containers/storage"
 graphroot = "/var/lib/containers/storage"
+# Enables a global transient storaga mode where all container metadata is stored on non-persistant media
+# This guaranteea a fresh state on boot.
+# However it is not compabible with a traditional model where containers persist across reboots.
+# Use with `podman-clean-transient.service`
+transient_store = true
 
 [storage.options]
 # We add a custom "/usr/share/containers/storage" here to allow readonly in-image containers