Change setup behavior of the AuthenticationManager to a lazy approach

The authentication manager should only try to set up all backends when
necessary. Remove the backend setup from the constructor and call it only when it is actually needed.

fixes #5506

library/Icinga/Authentication/Manager.php

@@ -94,6 +94,20 @@ class Manager
      **/
     private $session = null;
 
+    /**
+     * The configuration
+     *
+     * @var Zend_Config
+     */
+    private $config = null;
+
+    /**
+     * If the backends are already created.
+     *
+     * @var Boolean
+     */
+    private $initialized = false;
+
     /**
      * Creates a new authentication manager using the provided config (or the
      * configuration provided in the authentication.ini if no config is given)
@@ -112,16 +126,12 @@ class Manager
         if ($config === null && !(isset($options['noDefaultConfig']) && $options['noDefaultConfig'] == true)) {
                 $config = IcingaConfig::app('authentication');
         }
-
-        if ($config !== null) {
-            $this->setupBackends($config);
-        }
-
         if (!isset($options['sessionClass'])) {
             $this->session = new PhpSession();
         } else {
             $this->session = $options['sessionClass'];
         }
+        $this->config = $config;
     }
 
     /**
@@ -226,6 +236,7 @@ class Manager
      */
     public function getUserBackend($name)
     {
+        $this->initBackends();
         return (isset($this->userBackends[$name])) ?
             $this->userBackends[$name] : null;
     }
@@ -249,6 +260,7 @@ class Manager
      */
     public function getGroupBackend($name)
     {
+        $this->initBackends();
         return (isset($this->groupBackends[$name])) ?
             $this->groupBackends[$name] : null;
     }
@@ -263,8 +275,9 @@ class Manager
      */
     private function getBackendForCredential(Credential $credentials)
     {
-        $authErrors = 0;
+        $this->initBackends();
 
+        $authErrors = 0;
         foreach ($this->userBackends as $userBackend) {
 
             $flag = false;
@@ -309,6 +322,17 @@ class Manager
         return null;
     }
 
+    /**
+     * Ensures that all backends are initialized
+     */
+    private function initBackends()
+    {
+        if (!$this->initialized) {
+            $this->setupBackends($this->config);
+            $this->initialized = true;
+        }
+    }
+
     /**
      * Try to authenticate the current user with the Credential (@see Credential).
      *
@@ -321,6 +345,7 @@ class Manager
      */
     public function authenticate(Credential $credentials, $persist = true)
     {
+        $this->initBackends();
         if (count($this->userBackends) === 0) {
             Logger::error('AuthManager: No authentication backend provided, your users will never be able to login.');
             throw new ConfigError(