Add filter to allow customizing who can flush the cache (#535)

* Add filter and constant to allow customizing who can manage the plugin

* Update CHANGELOG.md

* Update README.md

---------

Co-authored-by: Till Krüss <[email protected]>

Author: pmgarman

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 - Fixed several issues with Predis and cluster/replicated connection
 - Fixed rare fatal error in `show_error_and_die()` (one more time)
+- Add `redis_cache_manager_capability` filter
+- Add `WP_REDIS_MANAGER_CAPABILITY` constant
 
 ## 2.5.2
 

README.md

@@ -64,6 +64,7 @@ The Redis Object Cache plugin comes with vast set of configuration options. If y
 | `WP_REDIS_DISABLE_BANNERS`           | `false`     | Disables promotional banners and notices |
 | `WP_REDIS_DISABLE_COMMENT`           | `false`     | Disables HTML source comment |
 | `WP_REDIS_SSL_CONTEXT`               | `[]`        | TLS connection options for `tls` or `rediss` scheme |
+| `WP_REDIS_MANAGER_CAPABILITY`        |             | The capability a user must have to manage the plugin |
 
 </details>
 
@@ -230,11 +231,12 @@ Redis Object Cache has various WP CLI commands, for more information run `wp hel
 
 Redis Object Cache has various hooks and the commonly used ones are listed below.
 
-| Filter / Action                         | Description                                       |
-| --------------------------------------- | ------------------------------------------------- |
-| `redis_cache_expiration`                | Filters the cache expiration for individual keys  |
-| `redis_cache_validate_dropin`           | Filters whether the drop-in is valid              |
+| Filter / Action                         | Description |
+| --------------------------------------- | ----------- |
+| `redis_cache_expiration`                | Filters the cache expiration for individual keys |
+| `redis_cache_validate_dropin`           | Filters whether the drop-in is valid |
 | `redis_cache_add_non_persistent_groups` | Filters the groups to be marked as non persistent |
+| `redis_cache_manager_capability`        | Filters the capability a user needs to manage the plugin |
 
 ## Footnotes
 

includes/class-plugin.php

@@ -1565,7 +1565,19 @@ public function obscure_url_secrets( $url ) {
      * @return string
      */
     public function manage_redis_capability() {
-        return is_multisite() ? 'manage_network_options' : 'manage_options';
+        if ( defined( 'WP_REDIS_MANAGER_CAPABILITY' ) && WP_REDIS_MANAGER_CAPABILITY ) {
+            return WP_REDIS_MANAGER_CAPABILITY;
+        }
+        
+        $capability = is_multisite() ? 'manage_network_options' : 'manage_options';
+
+        /**
+         * Filters the capability used to determine if a user can manage Redis.
+         *
+         * @since 2.6.0
+         * @param string   $capability The default capability to determine if the user can manage cache.
+         */
+        return apply_filters( 'redis_cache_manager_capability', $capability );
     }
 
     /**