More generic way to retrieve web server user

Mage/Task/BuiltIn/Filesystem/PermissionsWritableByApacheTask.php

@@ -1,32 +0,0 @@
-<?php
-namespace Mage\Task\BuiltIn\Filesystem;
-
-/**
- * Task for giving Apache write permissions on given paths.
- *
- * Usage :
- *   pre-deploy:
- *     - filesystem/permissions-writable-by-apache: {paths: /var/www/myapp/app/cache:/var/www/myapp/app/cache, recursive: false, checkPathsExist: true}
- *   on-deploy:
- *     - filesystem/permissions-writable-by-apache: {paths: app/cache:app/logs, recursive: false, checkPathsExist: true}
- *
- * @author Jérémy Huet <jeremy.huet@gmail.com>
- */
-class PermissionsWritableByApacheTask extends PermissionsTask
-{
-    public function init()
-    {
-        parent::init();
-
-        $this->setGroup('www-data')
-             ->setRights('g+w');
-    }
-
-    /**
-     * @return string
-     */
-    public function getName()
-    {
-        return "Gives write permissions to Apache user for given paths [built-in]";
-    }
-}

Mage/Task/BuiltIn/Filesystem/PermissionsWritableByWebServerTask.php

@@ -0,0 +1,54 @@
+<?php
+namespace Mage\Task\BuiltIn\Filesystem;
+
+use Mage\Task\SkipException;
+
+/**
+ * Task for giving web server write permissions on given paths.
+ *
+ * Usage :
+ *   pre-deploy:
+ *     - filesystem/permissions-writable-by-web-server: {paths: /var/www/myapp/app/cache:/var/www/myapp/app/cache, recursive: false, checkPathsExist: true}
+ *   on-deploy:
+ *     - filesystem/permissions-writable-by-web-server: {paths: app/cache:app/logs, recursive: false, checkPathsExist: true}
+ *
+ * @author Jérémy Huet <jeremy.huet@gmail.com>
+ */
+class PermissionsWritableByWebServerTask extends PermissionsTask
+{
+    /**
+     * Set group with web server user and give group write permissions.
+     */
+    public function init()
+    {
+        parent::init();
+
+        $this->setGroup($this->getParameter('group', $this->getWebServerUser()))
+             ->setRights('g+w');
+    }
+
+    /**
+     * @return string
+     */
+    public function getName()
+    {
+        return "Gives write permissions to web server user for given paths [built-in]";
+    }
+
+    /**
+     * Tries to guess the web server user by going thru the running processes.
+     *
+     * @return string
+     * @throws SkipException
+     */
+    protected function getWebServerUser()
+    {
+        $this->runCommand("ps aux | grep -E '[a]pache|[h]ttpd|[_]www|[w]ww-data|[n]ginx' | grep -v root | head -1 | cut -d\  -f1", $webServerUser);
+
+        if (empty($webServerUser)) {
+            throw new SkipException("Can't guess web server user. Please check if it is running or force it by setting the group parameter");
+        }
+
+        return $webServerUser;
+    }
+}