resilient: prevents all resilient instances to start backing up at the same time

stack/resilient/buildout.cfg

@@ -59,7 +59,7 @@ mode = 0644
 recipe = slapos.recipe.template
 url = ${:_profile_base_location_}/pbsready-export.cfg.in
 output = ${buildout:directory}/pbsready-export.cfg
-md5sum = c819c0711d58e952f16b93d96654139c
+md5sum = 2f08cfdc1955bad5bd06ba79ee5a5780
 mode = 0644
 
 [template-pull-backup]

stack/resilient/pbsready-export.cfg.in

@@ -58,7 +58,9 @@ pidfile = $${resilient-directory:pid}/$${:name}.pid
 recipe = slapos.cookbook:cron.d
 name = backup
 frequency = $${slap-parameter:resiliency-backup-periodicity}
-command = $${notifier-exporter:wrapper} --transaction-id `date +%s`
+# Sleep from 1 to 6 hours before backing up (disks/network IO optimization)
+sleep-command = ${bash:location}/bin/bash -c "sleep $((RANDOM%(60*60*6)))"
+command = ($${:sleep-command}; $${notifier-exporter:wrapper} --transaction-id `date +%s`)
 
 [slap-parameter]
 # In cron.d format (i.e things like */15 * * * * are accepted).