Nexus 9000 Standalone Programmability Lab Version 1.18

Transcription

1 Nexus 9000 Standalone Programmability Lab Version 1.18

2 ATTENTION The information contained in this guide is for training purposes only. This guide contains information and activities that, while beneficial for purposes of training in close, nonproductive environment, can result in downtime or other severe consequences and, therefore, are not intended as a reference guide. No part of this book may be reproduced in any form or by any means (graphic, electronic, mechanical, including photocopying, recording or taping, or storage in an electronic retrieval system). Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page2

3 Table of Contents Nexus 9000 Standalone Programmability Overview...4 Using the Built-in Python Interpreter...4 Running Python from the Bash Shell...7 Modifying Python Scripts Using vi Editor in Bash Shell...8 Working with Guest Shell Running Custom Python Scripts on the Nexus 9K Locally Running Open Source Python Scripts from GitHub on the Nexus 9K Switch Locally Using NX-API Python Script to Program the Switch Remotely Running Python Scripts with Embedded Event Manager (EEM) Running Python Scripts with Scheduler Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page3

4 Nexus 9000 Standalone Programmability Overview The Nexus 9000 comes with a rich set of programmatic scripting capabilities. Running a Nexus 9000 standalone image, network operators have the flexibility to invoke Python scripts locally or remotely using the following methods: Method Local Remote Native Python Interpreter X Bash Shell X NX-API X Embedded Event Manager (EEM) X Scheduler X In this lab, you will learn how to invoke Python scripts using all the methods summarized above. Using the Built-in Python Interpreter The purpose of this exercise is to get familiar with the built-in Python interpreter on the Nexus 9K running in standalone mode. Step 1 From Remote Desktop, use Putty to SSH into your assigned POD per the POD information sheet. Start -> Remote Desktop Connection Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page4

5 Step 2 Enter username and password per the POD info sheet: Step 3 Open a PuTTY session to the management interface of your pod. Step 4 Log in to your pod with the username admin and password!cisco123 Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page5

6 Step 5 Enter the built-in Python shell by using the python command. Question: Which version of Python is running? Step 6 Next, type from cli import * to import the CLI library. From there, you can now change the switch s hostname to Python_Example by calling the cli() function and passing the conf, hostname commands. Make sure you have a space before and after the semi-colon ( ; ): Step 7 Pass the show switchname CLI command through the Python interpreter to confirm that the hostname has changed. Step 8 Create interface loopback5 and assign the IP address /24 to the interface. Note: If interface loopback5 already exists, manually remove the loopback interface from the CLI then try again from the Python shell. Step 9 Exit the Python interpreter by issuing exit() then show the running configuration of loopback 5. Confirm that the hostname has also changed to Python_Example. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page6

7 Running Python from the Bash Shell The purpose of this exercise is to get familiar with running Python from the bash shell. Step 1 Enable the bash shell feature. By default, it is disabled. Step 2 Now enter the bash shell and run Python. Note: Your prompt will end with a $ when you enter the bash shell. Your prompt will end with >>> when you enter the Python interpreter. Step 3 Change the hostname to your original pod name, N9K-Standalone-Pod-#, and delete interface loopback5. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page7

8 Step 4 Exit Python then exit the bash shell. Step 5 Verify that the hostname was changed and that loopback5 no longer exists. Modifying Python Scripts Using vi Editor in Bash Shell The purpose of this exercise is to demonstrate using the vi editor in the NX-OS Bash shell. Having a simple text editor available in NX-OS saves time and enables rapid development and testing, for example, when making small changes to Python scripts or files residing locally on a switch without the need to sync the file from a remote SCP/FTP client. In this exercise, we will create a text file named helloworld.py and add simple Python instructions to create a loopback interface with description using the vi editor in Bash shell. Step 1 Enter the Bash shell CLI command: run bash Step 2 Create a new text file named helloworld.py under the directory /bootflash/scripts Bash commands: pwd cd /bootflash/scripts touch helloworld.py ls /bootflash/scripts Displays present working directory Changes to directory /bootflash/scripts Creates text file named helloworld.py Lists contents in present directory Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page8

9 Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page9

10 Step 3 Open the helloworld.py using the vi editor Bash command: vi helloworld.py Step 4 Add Python code Vi editor command: i Small case letter i. This will allow you to insert text. This essentially takes you into vi editor mode. Python code: import cli cli.cli( conf t ; interface loop100 ; description test ) cli.clip( show run interface loop100 ) (Note: Again, make sure there are spaces between each semi-colon ( ; ) in your Python script) Step 5 Save Python code Vi editor commands: Esc key This key will exit editor mode and take you into the vi command mode :wq! This vi command will write (w) changes to the file, quit (q) the vi editor, then close the Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page10

11 window (!). Step 6 Invoke Python script Bash command: python helloworld.py Output Step 7 Step 8 Modify your Python script using the vi editor to change the interface description Invoke your Python script again to verify your changes Working with Guest Shell The purpose of this exercise is to understand the capabilities the Nexus 9000 provides using guest shell (Linux container - LXC) which is a feature available starting with NX-OS release 6.1(2)I3(1). Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page11

12 Step 1 Enter the command show virtual-service list to check if guestshell+ service is activated or not. If not activated, enable the virtual-service using the command guestshell enable which installs and activates the guest shell using the specified software package (OVA file) or the embedded package from the system image (when no package is specified). Initially, guest shell packages are only available by being embedded in the system image. Step 2 Note: The service can take up to 2 minutes to be activated. The guest shell starts an Open-SSH v6.2p2 server upon boot up. The server listens on port 4022 on the localhost ip address interface only. This provides the password-less connectivity into the guest shell from the NX-OS when the guestshell keyword is entered. Step 3 Enter the command guestshell to get access to the container and the bash prompt Step 4 By default communication is performed using the default vrf. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page12

13 chvrf is a tool that allows users to choose the vrf for LXC to communicate to the rest of network. The guest shell provides an application (dohost) to allow users to issue NX-OS commands form guest shell environment. Commands issued on the host through the dohost command are run with network-admin level privileges. Any configuration changes using "dohost" would show up when issuing show run from the NXOS side. It can be used for both show and configuration commands, multiple commands can be entered separated by space. Step 5 Note: The {0} is indicative of return code of the command the following { } contains the output from the command. The PIP python package manager is included in the guest shell to allow the network-admin to install new python packages. By default, the Yum RPM package manager is also included in the guest shell for the installation of software packages. Yum is pointed to the yocto repository. Yum can be pointed to one or more repositories at any time by modifying the yumrepo_x86_64.repo file or by adding a new.repo file in the repos.d directory. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page13

14 Step 6 run guestshell command from NX-OS CLI allows you to run commands in guestshell from the CLI Step 7 There are other guestshell commands which allow you to set the behavior of this feature (resource reservation etc.) Step 8 Enter the command guestshell destroy to disable and uninstall the package. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page14

15 Running Custom Python Scripts on the Nexus 9K Locally The purpose of this exercise is to create a custom Python script on a remote machine then run it locally on a Nexus 9K running in standalone mode. Step 1 On the server, navigate to Start > All Programs > Python 2.7 > IDLE (Python GUI). Step 2 In the Python shell, navigate to File > New File. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page15

16 Step 3 Create a script that will create changes to two interfaces where 1. Ethernet1/2 will be routed, assigned IP address /24 and enabled 2. Ethernet1/3 will be access, assigned to VLAN 3456 and enabled Then have the script: 1. Show each of the interfaces 2. Issue show int brief 3. Issue show ip int brief with a pause between each. Example: Note how cli( ) is used for configuration while clip( ) is used for printing show commands. Step 4 Save the script in the tftp server directory named C:\TFTP-Root and name the file Int_Change.py Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page16

17 Step 5 Start the TFTP server by navigating to Start > All Programs > SolorWinds TFTP Server > TFTP Server. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page17

18 Step 6 From the switch, copy the script to bootflash: where XX is the private IP address specific to your TFTP server. To obtain the private IP address specific to your TFTP server, type ipconfig from the Windows command prompt: When asked what VRF to use, enter management. N9K-Standalone-Pod-1(config-if)# copy tftp:// xx/int_change.py bootflash: Enter vrf (If no input, current vrf default is considered): management Note: If you get a TFTP get operation failed:file not found message, check to make sure the filename Int_Change.py was saved to bootflash with the.py file extension. Step 7 From the CLI, show that both interfaces are at default. N9K-Standalone-Pod-1(config-if)# show run Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page18

19 Step 8 Run the Python script you just created. Press Enter at each pause to show the changes that you made. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page19

20 Step 9 Set interfaces Ethernet1/2 and Ethernet1/3 back to default settings when you are done: Step 10 (Bonus) Try creating your own Python script to perform the actions in Step 9. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page20

21 Running Open Source Python Scripts from GitHub on the Nexus 9K Switch Locally There are a host of simple Python scripts available in the Nexus 9K GitHub community to help network engineers quickly get started and begin their journey towards becoming a DevOps engineer. This lab will show how to download a sample Python script from GitHub to experiment with. Step 1 If you haven t already done so, download and install Git - Git will be used on your local server to pull Python scripts from GitHub. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page21

26 Step 2 Go to the URL below and note the HTTPS clone URL. You will use this URL when cloning the repository using Git on your local server: Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page26

27 Step 3 Start the Git bash shell by navigating to Start > All Programs > Git > Git Bash Step 4 From the Git bash shell, move to the C:\TFTP-Root directory Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page27

28 Step 5 Now from the Git bash shell, enter: git clone Example: This command effectively pulls the entire GitHub repository called who-movedmy-cli to your server s C:\TFTP-Root directory. This repository contains sample Nexus 9K Python scripts you can experiment with. Step 6 From the Nexus 9K, TFTP the following Python scripts to bootflash: 1. interface_rate.py 2. pingrange.py Example: N9K-Standalone-Pod-1# copy tftp://<rdp-server-private-ip-address>/who-moved-my-cli/interface_rate.py bootflash: (Note: Run the TFTP server on your machine if the service has not been started by navigating to Start > All Programs > SolarWinds TFTP server > TFTP Server.) Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page28

29 Step 7 Run bash shell and enter ls *.py from the bootflash directory to confirm the scripts were transferred successfully: (Note: If bash-shell has not been enabled, enter feature bash-shell from config mode and try again.) You can also issue the dir command from the CLI prompt to see the scripts: Step 8 Run the python interface_rate.py script to show the loading of all interfaces on the Cisco Nexus 9000 Series Switch. Step 9 Run the interactive script pingrange.py. This Python script requires you to enter a range of IP addresses. You can put a range in any octet that you want. For this example, ping the management interfaces of the PODS. The IP address range will be in vrf name management. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page29

30 Using NX-API Python Script to Program the Switch Remotely The purpose of this exercise is to demonstrate how to invoke an NX-API Python script to remotely program a Nexus 9K running in standalone mode. Step 1 Enable the nxapi feature on the switch. The nxapi feature is disabled by default. Step 2 From the Chrome browser, go to: Step 3 Click Raw and save the script to the C:\TFTP-Root directory as nxapi_basics.py. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page30

31 Step 4 Modify the Python file using a text editor and provide the IP address of the switch assigned to your POD along with username and password. You will need to scroll down to the Main Module section (lines ). Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page31

33 Step 5 Go through the script to understand what it is doing. You don t need to understand everything. Just begin under the MAIN MODULE section of the Python code. Once you are done, open the Command Prompt and invoke the Python script. Step 6 (Bonus) The script should have created new Vlan interfaces ranging from Vlan 555 through Vlan 564 and created a Loopback99 interface. Upon verification, modify the script so Vlan 555 through Vlan 564 and Loopback99 get removed. Using Embedded Event Manager (EEM) to run Python Scripts The purpose of this exercise is to demonstrate how to trigger a Python script using the Embedded Event Manager (EEM). For this particular exercise, EEM will be triggered by issuing a CLI command. However, the trigger can be any supported event supported by EEM, for example, a syslog message or memory threshold event. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page33

34 Example of EEM events supported as of version 6.1(2)I3(1): Step 1 Using the Int_Change.py script loaded in bootflash: from a previous exercise, configure the following EEM policy: Step 2 Verify Ethernet1/2 and Ethernet 1/3 have not been configured Step 3 Trigger the EEM policy by issuing the CLI command show run eem then verify the configurations of Ethernet1/2 and Ethernet1/3 have been changed by the Int_Change.py script. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page34

35 Step 4 Set interfaces Ethernet1/2 and Ethernet1/3 back to default settings when you are done: Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page35

36 Using Scheduler to Run Python Scripts The purpose of this exercise is to demonstrate using the NX-OS scheduler to run Python scripts. Common use cases would be the periodic collection of diagnostic information or application of QoS policies to give precedence to critical traffic during a specific time. For simplicity, we will use the scheduler to invoke the python script helloworld.py that was created in an earlier exercise every 1 minute. Step 1 Enable the scheduler feature CLI command: feature scheduler Step 2 Schedule job CLI commands: scheduler job name helloworld python bootflash:/scripts/helloworld.py exit scheduler schedule name helloworld job name helloworld time start now repeat 0:0:1 Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page36

37 Step 3 Verify job is running as specified. CLI command: show scheduler schedule Activity Verification You have completed this activity when you have achieved these objectives: You ran Python commands from the CLI and bash shell. You created/modified a Python script using the vi editor in bash shell You created a Python script then ran the script on the switch locally. You cloned Python scripts from GitHub and ran them locally on the switch. You made changes to the switch configuration remotely using NX-API. You invoked a Python script by triggering an EEM applet using a CLI event. You invoked a Python script by using the NX-OS scheduler Congratulations! You have completed the Nexus 9000 Standalone Programmability lab. Nexus 9000 Standalone Programmability Lab Guide Ver 1.18 OneCloud Consulting Page37