From 21c95657eff96c17e4a87c123589e01c2fbeb059 Mon Sep 17 00:00:00 2001
From: Takashi Kajinami <tkajinam@redhat.com>
Date: Mon, 20 Jun 2022 20:12:13 +0900
Subject: [PATCH] Add sleep in cache cron jobs

... so that users can avoid executing the same cron command at the same
time in multiple nodes.

Technically this can be done without this change by setting a different
cron job schedule in each node but it requires complicated parameter
setting.

Change-Id: I596879d5d46f23e54fe344d5bf93a57837a6d287
---
 manifests/cache/cleaner.pp                    | 19 +++++++++++++++---
 manifests/cache/pruner.pp                     | 20 +++++++++++++++----
 .../cache-cron-maxdelay-bfd1585eaa15aeda.yaml |  7 +++++++
 spec/classes/glance_cache_cleaner_spec.rb     |  3 ++-
 spec/classes/glance_cache_pruner_spec.rb      |  3 ++-
 5 files changed, 43 insertions(+), 9 deletions(-)
 create mode 100644 releasenotes/notes/cache-cron-maxdelay-bfd1585eaa15aeda.yaml

diff --git a/manifests/cache/cleaner.pp b/manifests/cache/cleaner.pp
index d9ae4cad..86368ee1 100644
--- a/manifests/cache/cleaner.pp
+++ b/manifests/cache/cleaner.pp
@@ -20,9 +20,15 @@
 #    (optional) Defaults to '*'.
 #
 #  [*command_options*]
-#    command options to add to the cronjob
+#    (optional) command options to add to the cronjob
 #    (eg. point to config file, or redirect output)
-#    (optional) Defaults to ''.
+#    Defaults to ''.
+#
+#  [*maxdelay*]
+#    (optional) In Seconds. Should be a positive integer.
+#    Induces a random delay before running the cronjob to avoid running
+#    all cron jobs at the same time on all hosts this job is configured.
+#    Defaults to 0.
 #
 class glance::cache::cleaner(
   $minute           = 1,
@@ -31,13 +37,20 @@ class glance::cache::cleaner(
   $month            = '*',
   $weekday          = '*',
   $command_options  = '',
+  $maxdelay         = 0
 ) {
 
   include glance::deps
   include glance::params
 
+  if $maxdelay == 0 {
+    $sleep = ''
+  } else {
+    $sleep = "sleep `expr \${RANDOM} \\% ${maxdelay}`; "
+  }
+
   cron { 'glance-cache-cleaner':
-    command     => "${glance::params::cache_cleaner_command} ${command_options}",
+    command     => "${sleep}${glance::params::cache_cleaner_command} ${command_options}",
     environment => 'PATH=/bin:/usr/bin:/usr/sbin',
     user        => $::glance::params::user,
     minute      => $minute,
diff --git a/manifests/cache/pruner.pp b/manifests/cache/pruner.pp
index ed9338f3..9d7615a7 100644
--- a/manifests/cache/pruner.pp
+++ b/manifests/cache/pruner.pp
@@ -20,9 +20,15 @@
 #    (optional) Defaults to '*'.
 #
 #  [*command_options*]
-#    command options to add to the cronjob
+#    (optional) command options to add to the cronjob
 #    (eg. point to config file, or redirect output)
-#    (optional) Defaults to ''.
+#    Defaults to ''.
+#
+#  [*maxdelay*]
+#    (optional) In Seconds. Should be a positive integer.
+#    Induces a random delay before running the cronjob to avoid running
+#    all cron jobs at the same time on all hosts this job is configured.
+#    Defaults to 0.
 #
 class glance::cache::pruner(
   $minute           = '*/30',
@@ -31,13 +37,20 @@ class glance::cache::pruner(
   $month            = '*',
   $weekday          = '*',
   $command_options  = '',
+  $maxdelay         = 0
 ) {
 
   include glance::deps
   include glance::params
 
+  if $maxdelay == 0 {
+    $sleep = ''
+  } else {
+    $sleep = "sleep `expr \${RANDOM} \\% ${maxdelay}`; "
+  }
+
   cron { 'glance-cache-pruner':
-    command     => "${glance::params::cache_pruner_command} ${command_options}",
+    command     => "${sleep}${glance::params::cache_pruner_command} ${command_options}",
     environment => 'PATH=/bin:/usr/bin:/usr/sbin',
     user        => $::glance::params::user,
     minute      => $minute,
@@ -46,6 +59,5 @@ class glance::cache::pruner(
     month       => $month,
     weekday     => $weekday,
     require     => Anchor['glance::config::end'],
-
   }
 }
diff --git a/releasenotes/notes/cache-cron-maxdelay-bfd1585eaa15aeda.yaml b/releasenotes/notes/cache-cron-maxdelay-bfd1585eaa15aeda.yaml
new file mode 100644
index 00000000..76ec8cc6
--- /dev/null
+++ b/releasenotes/notes/cache-cron-maxdelay-bfd1585eaa15aeda.yaml
@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    The ``glance::cache::cleaner`` class and the ``glance::cache::pruner``
+    class now support the ``maxdelay`` parameter. This parameter would be
+    useful in a multi-node deployment, to avoid launching the same cron command
+    at the same time in multiple nodes.
diff --git a/spec/classes/glance_cache_cleaner_spec.rb b/spec/classes/glance_cache_cleaner_spec.rb
index 04c8d0f1..47604b4f 100644
--- a/spec/classes/glance_cache_cleaner_spec.rb
+++ b/spec/classes/glance_cache_cleaner_spec.rb
@@ -33,11 +33,12 @@ describe 'glance::cache::cleaner' do
           :month            => '2',
           :weekday          => '3',
           :command_options  => '--config-dir /etc/glance/',
+          :maxdelay         => 3600,
         }
       end
       it 'configures a cron' do
         is_expected.to contain_cron('glance-cache-cleaner').with(
-          :command     => 'glance-cache-cleaner --config-dir /etc/glance/',
+          :command     => 'sleep `expr ${RANDOM} \\% 3600`; glance-cache-cleaner --config-dir /etc/glance/',
           :environment => 'PATH=/bin:/usr/bin:/usr/sbin',
           :user        => 'glance',
           :minute      => 59,
diff --git a/spec/classes/glance_cache_pruner_spec.rb b/spec/classes/glance_cache_pruner_spec.rb
index 350e0f7f..3bcd5985 100644
--- a/spec/classes/glance_cache_pruner_spec.rb
+++ b/spec/classes/glance_cache_pruner_spec.rb
@@ -32,11 +32,12 @@ describe 'glance::cache::pruner' do
           :month            => '2',
           :weekday          => '3',
           :command_options  => '--config-dir /etc/glance/',
+          :maxdelay         => 3600,
         }
       end
       it 'configures a cron' do
         is_expected.to contain_cron('glance-cache-pruner').with(
-          :command     => 'glance-cache-pruner --config-dir /etc/glance/',
+          :command     => 'sleep `expr ${RANDOM} \\% 3600`; glance-cache-pruner --config-dir /etc/glance/',
           :environment => 'PATH=/bin:/usr/bin:/usr/sbin',
           :user        => 'glance',
           :minute      => 59,