Now, we are ready to take a look around the usage. Let's start by connecting to the EOS node by creating an object in the interactive Python shell:

Python 3.5.2 (default, Nov 17 2016, 17:05:23)
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pyeapi
>>> arista1 = pyeapi.connect_to('Arista1')

We can execute show commands to the node and receive the output:

>>> import pprint
>>> pprint.pprint(arista1.enable('show hostname'))
[{'command': 'show hostname',
 'encoding': 'json',
 'result': {'fqdn': 'arista1', 'hostname': 'arista1'}}]

The configuration field can be either a single command or a list of commands using the config() method:

>>> arista1.config('hostname arista1-new')
[{}]
>>> pprint.pprint(arista1.enable('show hostname'))
[{'command': 'show hostname',
 'encoding': 'json',
 'result': {'fqdn': 'arista1-new', 'hostname': 'arista1-new'}}]
>>> arista1.config(['interface ethernet 1/3', 'description my_link'])
[{}, {}]

Note that command abbreviation (show run versus show running-config) and some extensions will not work:

>>> pprint.pprint(arista1.enable('show run'))
Traceback (most recent call last):
...
 File "/usr/local/lib/python3.5/dist-packages/pyeapi/eapilib.py", line 396, in send
 raise CommandError(code, msg, command_error=err, output=out)
pyeapi.eapilib.CommandError: Error [1002]: CLI command 2 of 2 'show run' failed: invalid command [incomplete token (at token 1: 'run')]
>>>
>>> pprint.pprint(arista1.enable('show running-config interface ethernet 1/3'))
Traceback (most recent call last):
...
pyeapi.eapilib.CommandError: Error [1002]: CLI command 2 of 2 'show running-config interface ethernet 1/3' failed: invalid command [incomplete token (at token 2: 'interface')]

However, you can always catch the results and get the desired value:

>>> result = arista1.enable('show running-config')
>>> pprint.pprint(result[0]['result']['cmds']['interface Ethernet1/3'])
{'cmds': {'description my_link': None, 'switchport access vlan 100': None}, 'comments': []}

So far, we have been doing what we have been doing with eAPI for show and configuration commands. Pyeapi offers various APIs to make life easier. In the following example, we will connect to the node, call the VLAN API, and start to operate on the VLAN parameters of the device. Let's take a look:

>>> import pyeapi
>>> node = pyeapi.connect_to('Arista1')
>>> vlans = node.api('vlans')
>>> type(vlans)
<class 'pyeapi.api.vlans.Vlans'>
>>> dir(vlans)
[...'command_builder', 'config', 'configure', 'configure_interface', 'configure_vlan', 'create', 'default', 'delete', 'error', 'get', 'get_block', 'getall', 'items', 'keys', 'node', 'remove_trunk_group', 'set_name', 'set_state', 'set_trunk_groups', 'values']
>>> vlans.getall()
{'1': {'vlan_id': '1', 'trunk_groups': [], 'state': 'active', 'name': 'default'}}
>>> vlans.get(1)
{'vlan_id': 1, 'trunk_groups': [], 'state': 'active', 'name': 'default'}
>>> vlans.create(10)
True
>>> vlans.getall()
{'1': {'vlan_id': '1', 'trunk_groups': [], 'state': 'active', 'name': 'default'}, '10': {'vlan_id': '10', 'trunk_groups': [], 'state': 'active', 'name': 'VLAN0010'}}
>>> vlans.set_name(10, 'my_vlan_10')
True

Let's verify that VLAN 10 was created on the device:

arista1#sh vlan
VLAN Name Status Ports
----- -------------------------------- --------- -------------------------------
1 default active
10 my_vlan_10 active

As you can see, the Python native API on the EOS object is really where Pyeapi excels beyond eAPI. It abstracts the lower-level attributes into the device object and makes the code cleaner and easier to read.

To round up this chapter, let's assume that we repeat the previous steps enough times that we would like to write another Python class to save us some work. The pyeapi_1.py script is shown as follows: 

      #!/usr/bin/env python3

      import pyeapi

      class my_switch():

          def __init__(self, config_file_location, device):
               # loads the config file
               pyeapi.client.load_config(config_file_location)
               self.node = pyeapi.connect_to(device)
               self.hostname = self.node.enable('show hostname')[0]
    ['result']['host name']
              self.running_config = self.node.enable('show running-
    config')

           def create_vlan(self, vlan_number, vlan_name):
               vlans = self.node.api('vlans')
               vlans.create(vlan_number)
               vlans.set_name(vlan_number, vlan_name) 

As you can see from the script, we automatically connect to the node and set the hostname and running_config upon connection. We also create a method to the class that creates VLAN by using the VLAN API. Let's try out the script in an interactive shell:

Python 3.5.2 (default, Nov 17 2016, 17:05:23)
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pyeapi_1
>>> s1 = pyeapi_1.my_switch('/tmp/.eapi.conf', 'Arista1')
>>> s1.hostname
'arista1'
>>> s1.running_config
[{'encoding': 'json', 'result': {'cmds': {'interface Ethernet27': {'cmds': {}, 'comments': []}, 'ip routing': None, 'interface face Ethernet29': {'cmds': {}, 'comments': []}, 'interface Ethernet26': {'cmds': {}, 'comments': []}, 'interface Ethernet24/4': h.': 
<omitted>
'interface Ethernet3/1': {'cmds': {}, 'comments': []}}, 'comments': [], 'header': ['! device: arista1 (DCS-7050QX-32, EOS-4.16.6M)n!n']}, 'command': 'show running-config'}]
>>> s1.create_vlan(11, 'my_vlan_11')
>>> s1.node.api('vlans').getall()
{'11': {'name': 'my_vlan_11', 'vlan_id': '11', 'trunk_groups': [], 'state': 'active'}, '10': {'name': 'my_vlan_10', 'vlan_id': '10', 'trunk_groups': [], 'state': 'active'}, '1': {'name': 'default', 'vlan_id': '1', 'trunk_groups': [], 'state': 'active'}}
>>>