Add Version method (#1152)

* adding method to get es version
* added functional test for getVersion
* using `version_compare` and `ELASTICSEARCH_VERSION`

Author: Oleg Andreyev

CHANGELOG.md

@@ -13,6 +13,7 @@ All notable changes to this project will be documented in this file based on the
 - Elastica\QueryBuilder\DSL\Query::geo_distance
 - Elastica\Aggregation\GeoCentroid [#1150](https://github.com/ruflin/Elastica/pull/1150)
 - [Multi value field](https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-function-score-query.html#_multi_values_fields) param for decay function.
+- Elastica\Client::getVersion [#1152](https://github.com/ruflin/Elastica/pull/1152)
 
 ### Improvements
 - Set PHP 7.0 as default development version

env/elasticsearch/Dockerfile

@@ -2,6 +2,7 @@ FROM elasticsearch:2.3.2
 MAINTAINER Nicolas Ruflin <[email protected]>
 
 # Dependencies
+ENV ELASTICSEARCH_VERSION 2.3.2
 ENV ES_IMAGE_PLUGIN_VER 1.7.1
 ENV ES_PLUGIN_BIN /usr/share/elasticsearch/bin/plugin
 

lib/Elastica/Client.php

@@ -67,6 +67,11 @@ class Client
      */
     protected $_logger;
 
+    /**
+     * @var string
+     */
+    protected $_version;
+
     /**
      * Creates a new Elastica client.
      *
@@ -87,6 +92,21 @@ public function __construct(array $config = [], $callback = null, LoggerInterfac
         $this->_initConnections();
     }
 
+    /**
+     * Get current version
+     *
+     * @return string
+     */
+    public function getVersion()
+    {
+        if ($this->_version) {
+            return $this->_version;
+        }
+
+        $data = $this->request('/')->getData();
+        return $this->_version = $data['version']['number'];
+    }
+
     /**
      * Inits the client connections.
      */

test/lib/Elastica/Test/ClientTest.php

@@ -23,6 +23,16 @@ public function testConstruct()
         $this->assertCount(1, $client->getConnections());
     }
 
+    /**
+     * @group functional
+     */
+    public function testGetVersion()
+    {
+        $client = $this->_getClient();
+        $this->assertNotEmpty($client->getVersion());
+        $this->assertTrue(version_compare($client->getVersion(), $_SERVER['ELASTICSEARCH_VERSION'], '>='));
+    }
+
     /**
      * @group functional
      */