Merge lp:~hloeung/ubuntu-repository-cache/splay-cron-daily into lp:ubuntu-repository-cache

[Haw Loeung]

Ensure daily apache2 graceful restart is splayed - LP:1918211

We ship out a random sleep script to cron.daily to ensure that
graceful restarts from logrotation is spread out across the various
units.

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Colin Misare (cmisare)]

LGTM

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision 331

[Junien F (axino)]

May I suggest RAND=$(( RANDOM % (MAX-MIN) + MIN )) ?

[Haw Loeung (hloeung)]

Thanks, follow up MP - https://code.launchpad.net/~hloeung/ubuntu-repository-cache/splay-cron-daily-2/+merge/399571

=== added file 'files/cron_random_sleep.sh'
--- files/cron_random_sleep.sh	1970-01-01 00:00:00 +0000
+++ files/cron_random_sleep.sh	2021-03-11 23:44:25 +0000
@@ -0,0 +1,23 @@
+#!/bin/bash
+
+# Taken from basenode.
+
+# Maximum of 20 mins.
+MAX=1200
+# Minimum of 30 secs.
+MIN=30
+
+RAND=$RANDOM
+(( RAND %= $MAX ))
+
+if [ $RAND -lt $MIN ]; then
+    echo $RAND
+    (( RAND += MIN ))
+fi
+
+# if we're running it from the command line, don't sleep
+if [ -t 0 ]; then
+    echo skipped sleep $RAND
+else
+    sleep $RAND
+fi
 
=== modified file 'reactive/ubuntu_repository_cache.py'
--- reactive/ubuntu_repository_cache.py	2021-03-08 22:18:19 +0000
+++ reactive/ubuntu_repository_cache.py	2021-03-11 23:44:25 +0000
@@ -6,6 +6,7 @@
 
 import os
 import pwd
+import shutil
 
 from charms import reactive
 from charms.layer import status
@@ -68,6 +69,10 @@
         LOG('Disabling {}'.format(azure_disk_warning))
         host.service_pause(azure_disk_warning)
 
+    # We want to ensure not all units rotate out and graceful
+    # restart/reload apache at the same time.
+    shutil.copy2('files/cron_random_sleep.sh', '/etc/cron.daily/000-cron-random-sleep')
+
     reactive.set_flag('ubuntu-repository-cache.configured')