Add HashClient retry options for the dogpile.cache backend

This patch specifies a set of options required to setup the HashClient
retry feature of dogpile.cache cache backend.

Original oslo.cache change:
https://review.opendev.org/c/openstack/oslo.cache/+/824944

Co-Authored-By: Hervé Beraud <hberaud@redhat.com>
Depends-On: https://review.opendev.org/826870
Change-Id: Ie5cd3bd20c2c446602baa0d87f33e4573c2eb36a

manifests/cache.pp

@@ -155,6 +155,22 @@
 #   (Optional) Number of seconds to sleep between each attempt.
 #   Default to $::os_service_default
 #
+# [*hashclient_retry_attempts*]
+#   (Optional) Amount of times a client should be tried
+#   before it is marked dead and removed from the pool in
+#   the HashClient's internal mechanisms.
+#   Default to $::os_service_default
+#
+# [*hashclient_retry_delay*]
+#   (Optional) Time in seconds that should pass between
+#   retry attempts in the HashClient's internal mechanisms.
+#   Default to $::os_service_default
+#
+# [*dead_timeout*]
+#   (Optional) Time in seconds before attempting to add a node
+#   back in the pool in the HashClient's internal mechanisms.
+#   Default to $::os_service_default
+#
 class nova::cache (
   $config_prefix                        = $::os_service_default,
   $expiration_time                      = $::os_service_default,
@@ -182,6 +198,9 @@ class nova::cache (
   $enable_retry_client                  = $::os_service_default,
   $retry_attempts                       = $::os_service_default,
   $retry_delay                          = $::os_service_default,
+  $hashclient_retry_attempts            = $::os_service_default,
+  $hashclient_retry_delay               = $::os_service_default,
+  $dead_timeout                         = $::os_service_default,
 ) {
 
   include nova::deps
@@ -213,5 +232,8 @@ class nova::cache (
     enable_retry_client                  => $enable_retry_client,
     retry_attempts                       => $retry_attempts,
     retry_delay                          => $retry_delay,
+    hashclient_retry_attempts            => $hashclient_retry_attempts,
+    hashclient_retry_delay               => $hashclient_retry_delay,
+    dead_timeout                         => $dead_timeout,
   }
 }

releasenotes/notes/add_cache_hashclient_retry_options-d0ce282343bb7fe9.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    Add options to configure pymemcache's HashClient retrying mechanisms
+    (dogpile.cache) backend.

spec/classes/nova_cache_spec.rb

@@ -36,6 +36,9 @@ describe 'nova::cache' do
           :enable_retry_client                  => '<SERVICE DEFAULT>',
           :retry_attempts                       => '<SERVICE DEFAULT>',
           :retry_delay                          => '<SERVICE DEFAULT>',
+          :hashclient_retry_delay               => '<SERVICE DEFAULT>',
+          :dead_timeout                         => '<SERVICE DEFAULT>',
+          :manage_backend_package               => true,
           :manage_backend_package               => true,
         )
       end
@@ -64,6 +67,9 @@ describe 'nova::cache' do
           :enable_retry_client                  => false,
           :retry_attempts                       => 2,
           :retry_delay                          => 0,
+          :hashclient_retry_attempts            => 2,
+          :hashclient_retry_delay               => 1,
+          :dead_timeout                         => 60,
           :manage_backend_package               => false,
         }
       end
@@ -95,6 +101,9 @@ describe 'nova::cache' do
           :enable_retry_client                  => false,
           :retry_attempts                       => 2,
           :retry_delay                          => 0,
+          :hashclient_retry_attempts            => 2,
+          :hashclient_retry_delay               => 1,
+          :dead_timeout                         => 60,
           :manage_backend_package               => false,
         )
       end