Add support for API Compatibility Header (#1142)

Author: ezimuel

src/Elasticsearch/ClientBuilder.php

@@ -635,11 +635,20 @@ public function build(): Client
             if (! isset($this->connectionParams['client']['headers'])) {
                 $this->connectionParams['client']['headers'] = [];
             }
+            $apiVersioning = getenv('ELASTIC_CLIENT_APIVERSIONING');
             if (! isset($this->connectionParams['client']['headers']['Content-Type'])) {
-                $this->connectionParams['client']['headers']['Content-Type'] = ['application/json'];
+                if ($apiVersioning === 'true' || $apiVersioning === '1') {
+                    $this->connectionParams['client']['headers']['Content-Type'] = ['application/vnd.elasticsearch+json;compatible-with=7'];
+                } else {
+                    $this->connectionParams['client']['headers']['Content-Type'] = ['application/json'];
+                }
             }
             if (! isset($this->connectionParams['client']['headers']['Accept'])) {
-                $this->connectionParams['client']['headers']['Accept'] = ['application/json'];
+                if ($apiVersioning === 'true' || $apiVersioning === '1') {
+                    $this->connectionParams['client']['headers']['Accept'] = ['application/vnd.elasticsearch+json;compatible-with=7'];
+                } else {
+                    $this->connectionParams['client']['headers']['Accept'] = ['application/json'];
+                }
             }
 
             $this->connectionFactory = new ConnectionFactory($this->handler, $this->connectionParams, $this->serializer, $this->logger, $this->tracer);

tests/Elasticsearch/Tests/ClientBuilderTest.php

@@ -296,4 +296,52 @@ public function testElasticClientMetaHeaderIsNotSentWhenDisabled()
             $this->assertFalse(isset($request['request']['headers']['x-elastic-client-meta']));
         }    
     }
+
+    public function getCompatibilityHeaders()
+    {
+        return [
+            ['true', true],
+            ['1', true],
+            ['false', false],
+            ['0', false]
+        ];
+    }
+
+    /**
+     * @dataProvider getCompatibilityHeaders
+     */
+    public function testCompatibilityHeader($env, $compatibility)
+    {
+        putenv("ELASTIC_CLIENT_APIVERSIONING=$env");
+
+        $client = ClientBuilder::create()
+            ->build();
+        
+        try {
+            $result = $client->info();
+        } catch (ElasticsearchException $e) {
+            $request = $client->transport->getLastConnection()->getLastRequestInfo();
+            if ($compatibility) {
+                $this->assertContains('application/vnd.elasticsearch+json;compatible-with=7', $request['request']['headers']['Content-Type']);
+                $this->assertContains('application/vnd.elasticsearch+json;compatible-with=7', $request['request']['headers']['Accept']);
+            } else {
+                $this->assertNotContains('application/vnd.elasticsearch+json;compatible-with=7', $request['request']['headers']['Content-Type']);
+                $this->assertNotContains('application/vnd.elasticsearch+json;compatible-with=7', $request['request']['headers']['Accept']);
+            }
+        }    
+    }
+
+    public function testCompatibilityHeaderDefaultIsOff()
+    {
+        $client = ClientBuilder::create()
+            ->build();
+        
+        try {
+            $result = $client->info();
+        } catch (ElasticsearchException $e) {
+            $request = $client->transport->getLastConnection()->getLastRequestInfo();
+            $this->assertNotContains('application/vnd.elasticsearch+json;compatible-with=7', $request['request']['headers']['Content-Type']);
+            $this->assertNotContains('application/vnd.elasticsearch+json;compatible-with=7', $request['request']['headers']['Accept']);
+        }    
+    }
 }