package/execd: clean up any lingering containers at boot

To be able to handle container restarts, incl. restart policy, at
runtime, most of the container data lives in /var/lib/containers,
which on most systems is backed by a persistent store.

As of issue #823 we no longer keep a writable layer for containers,
nor should we cache container state across reboots, all containers
are recreated at boot.  This task cleans up any lingering state.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

board/common/rootfs/usr/sbin/container

@@ -273,6 +273,7 @@ commands:
   create   NAME IMAGE NET  Create container NAME using IMAGE with networks NET
   delete  [network] NAME   Remove container NAME or network NAME from all containers
   exec     NAME CMD        Run a command inside a container
+  flush                    Clean up lingering containers and associated anonymous volumes
   find    [ifname PID]     Find PID of container where '--net IFNAME' currently lives
                            or, find the name of our IFNAME inside the container @PID
   help                     Show this help text
@@ -425,6 +426,10 @@ case $cmd in
     exec)
 	podman exec -it "$@"
 	;;
+    flush)
+	echo "Cleaning up any lingering containers";
+	podman rm -av
+	;;
     find)
 	cmd=$1
 	pid=$2

package/execd/execd.conf

@@ -1,2 +1,4 @@
+task log:prio:local1.notice,tag:container-flush <pid/syslogd> \
+	[S] container flush -- Cleaning up lingering containers
 service log:prio:local1.err,tag:container \
 	[2345] execd /run/containers/queue /run/containers/active -- Container job runner