fixing cron in #602

Updated s6overlay to v3
Note:  xz-utils was added as a requirement for s6-overlay (using safe 5.4.1 instead of compromised 5.6.x versions)

rootfs/etc/services.d/collector-once/run

@@ -1,13 +1,25 @@
-#!/usr/bin/with-contenv bash
+#!/command/with-contenv bash
+
+# ensure not run (successfully) before
+if [ -f /tmp/custom-init-performed ]; then
+  echo 'INFO: custom init already performed'
+  s6-svc -D /run/service/collector-once     # prevent s6 from restarting service
+  exit 0
+fi
 
 echo "waiting for scrutiny service to start"
-s6-svwait -u /var/run/s6/services/scrutiny
-
-#tell s6 to only run this script once
-s6-svc -O /var/run/s6/services/collector-once
+s6-svwait -u /run/service/scrutiny
 
 # wait until scrutiny is "Ready"
 until $(curl --output /dev/null --silent --head --fail http://localhost:8080/api/health); do echo "scrutiny api not ready" && sleep 5; done
 
 echo "starting scrutiny collector (run-once mode. subsequent calls will be triggered via cron service)"
 /opt/scrutiny/bin/scrutiny-collector-metrics run
+
+# prevent script's core logic from running again
+touch /tmp/custom-init-performed
+
+# prevent s6 from restarting service
+s6-svc -D /run/service/collector-once
+
+exit 0