Added write() method #33

Closes #33

docs/source/backends/openwrt.rst

@@ -128,6 +128,36 @@ directly on the OpenWRT router where it can be finally  "restored" with ``sysupg
 Note that the restore command does not apply the configuration, to do this you have
 to reload the services manually or reboot the router.
 
+Write method
+------------
+
+.. automethod:: netjsonconfig.OpenWrt.write
+
+Example:
+
+.. code-block:: python
+
+    >>> import tarfile
+    >>> from netjsonconfig import OpenWrt
+    >>>
+    >>> o = OpenWrt({
+    ...     "interfaces": [
+    ...         {
+    ...             "name": "eth0",
+    ...             "type": "ethernet",
+    ...             "addresses": [
+    ...                 {
+    ...                     "proto": "dhcp",
+    ...                     "family": "ipv4"
+    ...                 }
+    ...             ]
+    ...         }
+    ...     ]
+    ... })
+    >>> o.write('dhcp-router', path='/tmp/')
+
+Will write the configuration archive in ``/tmp/dhcp-router.tar.gz``.
+
 JSON method
 -----------
 

netjsonconfig/backends/openwrt/openwrt.py

@@ -176,6 +176,23 @@ def generate(self):
         byte_object.seek(0)
         return byte_object
 
+    def write(self, name, path='./'):
+        """
+        Like ``generate`` but writes to disk.
+
+        :param name: file name, the tar.gz extension will be added automatically
+        :param path: directory where the file will be written to, defaults to ``./``
+        :returns: closed file object
+        """
+        byte_object = self.generate()
+        file_name = '{0}.tar.gz'.format(name)
+        if not path.endswith('/'):
+            path += '/'
+        f = open('{0}{1}'.format(path, file_name), 'wb')
+        f.write(byte_object.getvalue())
+        f.close()
+        return f
+
     def _add_files(self, tar, timestamp):
         """
         adds files specified in self.config['files']

tests/openwrt/test_backend.py

@@ -182,6 +182,18 @@ def test_generate(self):
         self.assertEqual(contents, expected)
         tar.close()
 
+    def test_write(self):
+        o = OpenWrt({
+            "general": {
+                "hostname": "test"
+            }
+        })
+        o.write(name='test', path='/tmp')
+        tar = tarfile.open('/tmp/test.tar.gz', mode='r')
+        self.assertEqual(len(tar.getmembers()), 1)
+        tar.close()
+        os.remove('/tmp/test.tar.gz')
+
     def test_templates_type_error(self):
         config = {
             "general": {