Migrations infra & working instance-control + commands

all-apps/instance-control/hooks/queue-restic-snapshot.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+# TODO the systemd unit should actually do this
+# touch /maintenance/maintenance.on
+# rm /maintenance/maintenance.on
+
+# for instance-control docker compose setup:
+# make a directory in /tmp for these pipes and mount that as a volume
+# into the container
+
+# TODO read 'version' arg from request and make sure it
+# matches the version of this script
+
+# use a named pipe
+printf "%s\t%s\t%s\n" "$HOOK_tag" "$HOOK_request_id" "$HOOK_path" > /tmp/restic/snapshot_trigger_pipe