From d389d8e0f0c8a8b72f795347decf7aaca31e5a6d Mon Sep 17 00:00:00 2001
From: Thomas Gelf <thomas@gelf.net>
Date: Tue, 6 May 2014 15:01:43 +0000
Subject: [PATCH] Re-establish Backend::createBackend

This partially reverts fcf7f7d6. The original intention was to have
no library code reading config. Moving code snippets to another lib
doesn't solve this. We need quick & easy access to a monitoring
backend, on CLI, in other modules and so forth. Duplicating so much
code again and again is not an option.

I prefer the former way of doing things unless we find a better
solution.
---
 .../monitoring/library/Monitoring/Backend.php | 51 +++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/modules/monitoring/library/Monitoring/Backend.php b/modules/monitoring/library/Monitoring/Backend.php
index e28b36be5..502f04c4c 100644
--- a/modules/monitoring/library/Monitoring/Backend.php
+++ b/modules/monitoring/library/Monitoring/Backend.php
@@ -8,6 +8,10 @@ use Icinga\Exception\ProgrammingError;
 use Icinga\Data\Selectable;
 use Icinga\Data\Queryable;
 
+use Icinga\Application\Config as IcingaConfig;
+use Icinga\Data\ResourceFactory;
+use Icinga\Exception\ConfigurationError;
+
 /**
  * Data view and query loader tied to a backend type
  */
@@ -39,6 +43,53 @@ class Backend implements Selectable, Queryable
         $this->type = $type;
     }
 
+    /**
+     * Create a backend
+     *
+     * @param   string $backendName Name of the backend or null for creating the default backend which is the first INI
+     *                              configuration entry not being disabled
+     *
+     * @return  Backend
+     * @throws  ConfigurationError  When no backend has been configured or all backends are disabled or the
+     *                              configuration for the requested backend does either not exist or it's disabled
+     */
+    public static function createBackend($backendName = null)
+    {
+        $allBackends = array();
+        $defaultBackend = null;
+        foreach (IcingaConfig::module('monitoring', 'backends') as $name => $config) {
+            if (!(bool) $config->get('disabled', false) && $defaultBackend === null) {
+                $defaultBackend = $config;
+            }
+            $allBackends[$name] = $config;
+        }
+        if (empty($allBackends)) {
+            throw new ConfigurationError('No backend has been configured');
+        }
+        if ($defaultBackend === null) {
+            throw new ConfigurationError('All backends are disabled');
+        }
+        if ($backendName === null) {
+            $backendConfig = $defaultBackend;
+        } else {
+            if (!array_key_exists($backendName, $allBackends)) {
+                throw new ConfigurationError('No configuration for backend ' . $backendName);
+            }
+            $backendConfig = $allBackends[$backendName];
+            if ((bool) $backendConfig->get('disabled', false)) {
+                throw new ConfigurationError(
+                    'Configuration for backend ' . $backendName . ' available but backend is disabled'
+                );
+            }
+        }
+        $resource = ResourceFactory::createResource(ResourceFactory::getResourceConfig($backendConfig->resource));
+        if ($backendConfig->type === 'ido' && $resource->getDbType() !== 'oracle') {
+            // TODO(el): The resource should set the table prefix
+            $resource->setTablePrefix('icinga_');
+        }
+        return new Backend($resource, $backendConfig->type);
+    }
+
     /**
      * Backend entry point
      *