make it possible to install sentinell independently; update MDs

Author: tomsajan

README.md

@@ -133,6 +133,15 @@ class { '::redis::sentinel':
 }
 ```
 
+If installation without redis-server is desired, set `require_redis` parameter to false, i.e
+```puppet
+class { 'redis::sentinel':
+  ...
+  require_redis => false,
+  ...
+}
+```
+
 ### Soft dependency
 
 When managing the repo, it either needs [puppetlabs/apt](https://forge.puppet.com/puppetlabs/apt) or [puppet/epel](https://forge.puppet.com/puppet/epel).

REFERENCE.md

@@ -1468,6 +1468,15 @@ class {'redis::sentinel':
 }
 ```
 
+If installation without redis-server is desired, set `require_redis` parameter to false, i.e
+```puppet
+class { 'redis::sentinel':
+  ...
+  require_redis => false,
+  ...
+}
+```
+
 #### Parameters
 
 The following parameters are available in the `redis::sentinel` class:
@@ -1846,6 +1855,14 @@ Data type: `Stdlib::Ensure::Service`
 
 Default value: `'running'`
 
+##### <a name="-redis--sentinel--require_redis"></a>`require_redis`
+
+Data type: `Boolean`
+
+Require redis base class. If set to false, sentinel is installed without redis server.
+
+Default value: `true`
+
 ## Defined types
 
 ### <a name="redis--instance"></a>`redis::instance`

manifests/sentinel.pp

@@ -139,6 +139,9 @@
 #     log_file   => '/var/log/redis/sentinel.log',
 #   }
 #
+# @param require_redis
+#   Require redis base class. If set to false, sentinel is installed without redis server.
+#
 class redis::sentinel (
   Optional[Variant[String[1], Sensitive[String[1]]]] $auth_pass = undef,
   Stdlib::Absolutepath $config_file = $redis::params::sentinel_config_file,
@@ -180,14 +183,17 @@
   Stdlib::Absolutepath $working_dir = $redis::params::sentinel_working_dir,
   Optional[Stdlib::Absolutepath] $notification_script = undef,
   Optional[Stdlib::Absolutepath] $client_reconfig_script = undef,
+  Boolean $require_redis = true,
 ) inherits redis::params {
   $auth_pass_unsensitive = if $auth_pass =~ Sensitive {
     $auth_pass.unwrap
   } else {
     $auth_pass
   }
 
-  require 'redis'
+  if $require_redis {
+    require 'redis'
+  }
 
   if $package_name != $redis::package_name {
     ensure_packages([$package_name], {