17. nso python examples - RAYKA (are you a network engineer?)

NSO python examples are the topic of this section.

In the previous section, we started learning the python maagic library to navigate the configuration of network devices through cisco NSO.

In this section we will see some other practical python maagic code examples to show, change and delete configuration through Cisco NSO.

Cisco NSO python maagic library code examples

In continue, we will see some python code examples using maagic library to show or change the configurtaion of network devices,

iterate devices configured in cisco nso

In the first example discussed in the previous section, we navigated through the configuration of a specific device, but in the first example in this section we want to iterate through all the devices added in Cisco NSO dynamically and via Python code.

This is the code to iterate through the devices configured in Cisco NSO.

import ncs

with ncs.maapi.single_read_trans("admin", "python") as t:
    root = ncs.maagic.get_root(t)
    for box in root.devices.device:
      print("devicename:", box.name)
      print("device model:", box.platform.model)
      print("device address:", root.devices.device[box.name].address)
      print("device authentication group:", root.devices.device[box.name].authgroup)
      print("!!!!!!!!!!!!!!!!!!!!!!!!!")

First, we create a read transaction to the root of Cisco NSO as we discussed in the previous section.

Then we use “root.devices.device” to iterate through the devices and for each device, we print out the device name, device model, device address, and device authentication group.

Let’s run the script and see the list of devices.

majid@majid-ubuntu:~/devnet/cisco_nso/12.cisco_nso_python_api$ python3 2.device_iteration.py
devicename: R1
device model: CSR1000V
device address: 192.168.2.91
device authentication group: RAYKA
!!!!!!!!!!!!!!!!!!!!!!!!!
devicename: asa0
device model: NETSIM
device address: 127.0.0.1
device authentication group: default
!!!!!!!!!!!!!!!!!!!!!!!!!
devicename: ios0
device model: NETSIM
device address: 127.0.0.1
device authentication group: default
!!!!!!!!!!!!!!!!!!!!!!!!!
devicename: ios1
device model: NETSIM
device address: 127.0.0.1
device authentication group: default
!!!!!!!!!!!!!!!!!!!!!!!!!
devicename: ios2
device model: NETSIM
device address: 127.0.0.1
device authentication group: default
!!!!!!!!!!!!!!!!!!!!!!!!!
devicename: iosxr0
device model: NETSIM
device address: 127.0.0.1
device authentication group: default
!!!!!!!!!!!!!!!!!!!!!!!!!
devicename: junos0
device model: None
device address: 127.0.0.1
device authentication group: default
!!!!!!!!!!!!!!!!!!!!!!!!!
devicename: nxos0
device model: NETSIM
device address: 127.0.0.1
device authentication group: default

sync devices with "sync-from()" method

When you configure network devices through Cisco NSO, it is important that the configuration of the network devices is already synchronized in Cisco NSO.

As you know, “sync-from” and “sync-to” are two methods in Cisco NSO that you can use to sync configuration from device to Cisco NSO or vice versa.

This also applies when you configure network devices via Python code.

As an example, let’s change some configurations directly in the network device to unsync the Cisco NSO with the network device.

Then we run a python code to change some configuration in network device.

As we expect, we receive the error „out of sync“.

majid@majid-ubuntu:~/devnet/cisco_nso/12.cisco_nso_python_api$ python3 4.add_configu.py
Traceback (most recent call last):
  File "/home/majid/devnet/cisco_nso/12.cisco_nso_python_api/4.add_configu.py", line 15, in <module>
    t.apply()
  File "/home/majid/nso-6.0/src/ncs/pyapi/ncs/maapi.py", line 1979, in apply
    self.maapi.apply_trans_flags(self.th, keep_open, flags)
  File "/home/majid/nso-6.0/src/ncs/pyapi/ncs/maapi.py", line 375, in proxy
    return real(self2.msock, *args, **kwargs)
_ncs.error.Error: Unknown error (65): Network Element Driver: device R1: out of sync

Therefore, in this example we will see how the configuration is synchronized in the Python code.

import ncs
with ncs.maapi.single_read_trans('admin', 'python') as t:
    root = ncs.maagic.get_root(t)
    device_object  = root.devices.device["R1"]
    #print(dir(device_object))
    result = device_object.sync_from()

majid@majid-ubuntu:~/devnet/cisco_nso/12.cisco_nso_python_api$ python3 3.sync_from_devices.py
majid@majid-ubuntu:~/devnet/cisco_nso/12.cisco_nso_python_api$ python3 4.add_configu.py
majid@majid-ubuntu:~/devnet/cisco_nso/12.cisco_nso_python_api$

After getting read transaction access to the root of Cisco NSO, we connect to the device “R1” in which we are going to sync the configuration.

We then use the “sync_from()” method to synchronize the configuration from the network device to the Cisco NSO.

In the previous section, we learned how to extract the list of methods using the “dir” command.

change the configuration of network devices

Now that the configuration is synced between NSO and network devices, we can change the configuration via Python code.

This is the code example to enable the CDP protocol globally and also change the IP address of an interface.

import ncs
with ncs.maapi.single_write_trans('admin', 'python') as t:
    root = ncs.maagic.get_root(t)
    device_object = root.devices.device["R1"].config

    # enable cdp
    device_object.ios__cdp.run = True

    # add loopback interface
    device_object.ios__interface["Loopback"].create("1337")
    device_object.ios__interface.Loopback["1337"].ip.address.primary.address = "192.168.1.1"
    device_object.ios__interface.Loopback["1337"].ip.address.primary.mask = "255.255.255.252"

    # commit the configuration
    t.apply()

The difference is that we need to open a write transaction to root of Cisco NSO.

Then we connect to the device whose configuration we are going to change.

The other difference is that we need to enter to the “config” section of the device.

Then the best way to find the path to any part of configuration is “xpath”, which we discussed in the previous section.

Once we have the path, we can easily change the value via Python code like we did in this code to enable CDP and change the IP address of a loopback interface.

Finally we have to commit the new configuration via „apply“ command.

Let’s run the Python code and then directly check the router interfaces to make sure the new loopback interface is configured.

R1#show ip int brief
Interface              IP-Address      OK? Method Status                Protocol
GigabitEthernet1       192.168.2.91    YES NVRAM  up                    up
GigabitEthernet2       unassigned      YES NVRAM  administratively down down
GigabitEthernet3       unassigned      YES NVRAM  administratively down down
Loopback100            4.5.6.7         YES NVRAM  up                    up
Loopback123            12.13.14.16     YES NVRAM  up                    up
Loopback135            1.3.5.7         YES NVRAM  up                    up
Loopback150            1.1.1.1         YES NVRAM  up                    up
Loopback1337           192.168.1.1     YES manual up                    up
R1#

delete the configuration of network devices

Another important requirement to be met via python code is deleting a configuration section.

import ncs
with ncs.maapi.single_write_trans('admin', 'python') as t:
    root = ncs.maagic.get_root(t)
    device_object = root.devices.device["R1"].config
    del device_object.ios__interface.Loopback["1337"]
    t.apply()

It is obvious that we need a write transaction to the device to delete a configuration.

Getting access to the nso and network device is like all other code examples.

The key point is to use „del“ command and then the path to reach the interesting part of the configuration. As always, the path to the configuration is extracted using the nso xpath option.

Finally we commit the configuration using „apply“ command.

Let’s run the script and then make sure that the new loopback interface is deleted from network device.

majid@majid-ubuntu:~/devnet/cisco_nso/12.cisco_nso_python_api$ python3 5.delete_config.py
majid@majid-ubuntu:~/devnet/cisco_nso/12.cisco_nso_python_api$

R1#show ip int brief
Interface              IP-Address      OK? Method Status                Protocol
GigabitEthernet1       192.168.2.91    YES NVRAM  up                    up
GigabitEthernet2       unassigned      YES NVRAM  administratively down down
GigabitEthernet3       unassigned      YES NVRAM  administratively down down
Loopback100            4.5.6.7         YES NVRAM  up                    up
Loopback123            12.13.14.16     YES NVRAM  up                    up
Loopback135            1.3.5.7         YES NVRAM  up                    up
Loopback150            1.1.1.1         YES NVRAM  up                    up

show command through "live-status" feature

The “live-status” feature is another nice feature that we have already talked about in cisco nso which allows us to run any “show” or “clear” commands in network devices through cisco nso.

The next two scripts are exactly to run “show” and “clear” commands through the python maagic “live-status” function.

This is the script to run „show ip interface brief“ command in a network device.

import ncs

with ncs.maapi.single_read_trans("admin", "python") as t:
    root = ncs.maagic.get_root(t)
    device_object = root.devices.device["R1"]

    #print(dir(device_object))
    #print(dir(device_object.live_status))
    #print(dir(device_object.live_status.ios_stats__exec))
    input1 = device_object.live_status.ios_stats__exec.show.get_input()
    input1.args = ["ip interface brief"]
    #input1.args = ["cdp neighbor detail"]
    output = device_object.live_status.ios_stats__exec.show(input1).result
    print(output)

#ios_stats__exec
#cisco_ios_xr_stats__exec
#nx_stats__exec

The first part of the script is like always to get root access to cisco nso and connect to the network device. For „show“ and „clear“ commands we need only read transnation.

The method „live_status“ is what we need to run in device object to get „live-status“ feature in python code.

Then, depending on the device type, we have different options to be able to run any exec command on a remote device. For example, we use “ios_stats__exec” to run an exec command on iOS devices.

It’s very easy to extract these methods via the “dir” option. I have already extracted for iOS, iOS XR and NX OS devices which are in order „ios_stats__exec“, „cisco_ios_xr_stats__exec“ and „nx_stats__exec“.

Them to run „show“ commands in the remote devices, we always use „show.get_input()“ to get the show command itself as an argument. The exact command without „show“ keyword will be given as the argument.

In our example, we give „ip interface brief“ command as the argument instead of „show ip interface brief“.

Finally „show“ methods and the given argument will be used to run exec command in the remote device.

The „result“ option will be used to get the result of the show commands.

Here we use „print“ command to display the reult on the screen.

Let’s run the python script and see the result of „show ip interafce brief“ command.

majid@majid-ubuntu:~/devnet/cisco_nso/12.cisco_nso_python_api$ python3 6.show_commands.py

Interface              IP-Address      OK? Method Status                Protocol
GigabitEthernet1       192.168.2.91    YES NVRAM  up                    up
GigabitEthernet2       unassigned      YES NVRAM  administratively down down
GigabitEthernet3       unassigned      YES NVRAM  administratively down down
Loopback100            4.5.6.7         YES NVRAM  up                    up
Loopback123            12.13.14.16     YES NVRAM  up                    up
Loopback135            1.3.5.7         YES NVRAM  up                    up
Loopback150            1.1.1.1         YES NVRAM  up                    up
R1#

clear counters through python maagic "live-status" feature

Finally, we run a “clear” command on a remote device using the „live-status“ function in the python script.

import ncs

with ncs.maapi.single_read_trans("admin", "python") as t:
    root = ncs.maagic.get_root(t)
    device_object = root.devices.device["R1"]

    input1 = device_object.live_status.ios_stats__exec.clear.get_input()
    input1.args = ["cdp counters"]
    output = device_object.live_status.ios_stats__exec.clear(input1).result
    print(output)

This is exactly like „show“ command but we use „clear.get_input()“ instead of „show.get_input()“ method to get clear command as an argument.

The command will be given as argument but without „clear“ command exactly like „show“ command.

And the result of clear command will be diplayed using „result“ method.

Result

These are some of the most important scripts using python „maagic“ liberary to show or change network device configuration through cisco nso.

But there are many other options that can be run this library.

You can find some other examples from this link.

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