Added Context Manager documentation

docs/tutorials/context_manager.rst

@@ -0,0 +1,18 @@
+Context Manager
+===============
+
+In the previous tutorial we used the methods ``open()`` to connect to the device and ``close()`` to disconnect.
+Using those methods are useful if you want to do complex or asynchronous code. However, for most situations you should
+try to stick with the context manager. It handles opening and closing the session automatically and it's the
+pythonic way:
+
+.. code-block:: python
+
+>>> from napalm import get_network_driver
+>>> driver = get_network_driver('eos')
+>>> with driver('localhost', 'vagrant', 'vagrant', optional_args={'port': 12443}) as device:
+...     print device.get_facts()
+...     print device.get_interfaces_counters()
+...
+{'os_version': u'4.15.2.1F-2759627.41521F', 'uptime': 2010, 'interface_list': [u'Ethernet1', u'Ethernet2', u'Management1'], 'vendor': u'Arista', 'serial_number': u'', 'model': u'vEOS', 'hostname': u'NEWHOSTNAME', 'fqdn': u'NEWHOSTNAME'}
+{u'Ethernet2': {'tx_multicast_packets': 1028, 'tx_discards': 0, 'tx_octets': 130744, 'tx_errors': 0, 'rx_octets': 0, 'tx_unicast_packets': 0, 'rx_errors': 0, 'tx_broadcast_packets': 0, 'rx_multicast_packets': 0, 'rx_broadcast_packets': 0, 'rx_discards': 0, 'rx_unicast_packets': 0}, u'Management1': {'tx_multicast_packets': 0, 'tx_discards': 0, 'tx_octets': 99664, 'tx_errors': 0, 'rx_octets': 105000, 'tx_unicast_packets': 773, 'rx_errors': 0, 'tx_broadcast_packets': 0, 'rx_multicast_packets': 0, 'rx_broadcast_packets': 0, 'rx_discards': 0, 'rx_unicast_packets': 0}, u'Ethernet1': {'tx_multicast_packets': 1027, 'tx_discards': 0, 'tx_octets': 130077, 'tx_errors': 0, 'rx_octets': 0, 'tx_unicast_packets': 0, 'rx_errors': 0, 'tx_broadcast_packets': 0, 'rx_multicast_packets': 0, 'rx_broadcast_packets': 0, 'rx_discards': 0, 'rx_unicast_packets': 0}}

docs/tutorials/first_steps_config.rst

@@ -13,7 +13,7 @@ Use the appropriate network driver to connect to the device::
     >>> device = driver('192.168.76.10', 'dbarroso', 'this_is_not_a_secure_password')
     >>> device.open()
 
-Configurations can be replaced entirely or merged into the existing device config. 
+Configurations can be replaced entirely or merged into the existing device config.
 You can load configuration either from a string or from a file.
 
 Replacing the Configuration
@@ -79,3 +79,9 @@ If for some reason you committed the changes and you want to rollback::
 
     >>> device.rollback()
 
+Disconnecting
+-------------
+
+To close the session with the device just do::
+
+    >>> device.close()

docs/tutorials/index.rst

@@ -5,3 +5,4 @@ Tutorials
    :maxdepth: 1
 
    first_steps_config
+   context_manager