add ping method to the client (influxdata#409)

* add ping method to the client

* capitalize and pep257 compliance

* one more try for pep257 compliance for the ping function

* Update client.py

* Update client_test.py

fixing up failing CI tests

* Update client_test.py

fixing up failing CI tests

influxdb/client.py

@@ -457,6 +457,19 @@ def write_points(self,
                                   retention_policy=retention_policy,
                                   tags=tags, protocol=protocol)
 
+    def ping(self):
+        """Check connectivity to InfluxDB.
+
+        :returns: The version of the InfluxDB the client is connected to
+        """
+        response = self.request(
+            url="ping",
+            method='GET',
+            expected_response_code=204
+        )
+
+        return response.headers['X-Influxdb-Version']
+
     @staticmethod
     def _batches(iterable, size):
         for i in xrange(0, len(iterable), size):

influxdb/tests/client_test.py

@@ -418,6 +418,18 @@ def test_query_fail(self):
         with _mocked_session(self.cli, 'get', 401):
             self.cli.query('select column_one from foo;')
 
+    def test_ping(self):
+        """Test ping querying InfluxDB version."""
+        with requests_mock.Mocker() as m:
+            m.register_uri(
+                requests_mock.GET,
+                "http://localhost:8086/ping",
+                status_code=204,
+                headers={'X-Influxdb-Version': '1.2.3'}
+            )
+            version = self.cli.ping()
+            self.assertEqual(version, '1.2.3')
+
     def test_create_database(self):
         """Test create database for TestInfluxDBClient object."""
         with requests_mock.Mocker() as m: