Introduction to Python for Network Engineers

Introduction to Programming

• Why Learn to Program
  • Operational Efficiency
  • Human Error
  • How Bad?
  • What to do?
  • Your Career will thank you
  • Fear
  • The Future
• Why Python
  • TIOBE Programming Community Index
  • Which language to start with?
  • Why Python?
  • History of Python
  • Everything is an object
  • Around here for a long time
  • Portability
  • Readability
  • Batteries Included
  • Software examples with Python
• Programming Paradigms
  • Procedural Programming
    • First do this, then do that.
    • Organizing steps, modules, submodules etc.
  • Object Oriented Programming
  • Functional Programming

The Software Development Lifecycle at Bird View

• Gathering Information
• Initial Design
• Implementation
• Testing
• Debugging & Maintenance & Feature Requests
• Does any of these matter

A History of Interacting with Network Devices

• TCL and Expect
  • TCL - 1988 Tool Command Language
  • Expect - TCL Extension
• Telnet & SSH
• SNMP

Beyond Screen Scraping

• What is NETCONF?
• Comparing NETCONF and Other Methods
  • NETCONF vs Screen Scraping
  • NETCONF vs SNMP
• What is YANG?
• Python Embedded in the OS

Python Programming Environment

Choosing an Operating System

• Why choose Linux?
• virtualenv & virtualenvwrapper
  • LAB 1

Configuring your Text Editor

• Indentation
• Spaces over tabs
• Source File Encoding
• Comments

Python Interactive Interpreter

• Running the Interpreter
• Running code Inside the Interpreter
• Learning with the Interpreter

Running your Python Scripts

• Saving your Source Files
• Executing your Source Files
• What does the Shebang #! Line do?

 

Python Fundamentals

Object/Execution Model

• Everything is an Object
• Two types of Objects
  • Mutable
  • Immutable
• Statements and Expressions

Variables

• Traditional Variable Types
• Variables in Python

Data Types

• Strings
• Integers
• Floats
• Lists
• Dictionaries
• Tuples

Control Structures

• If/Else/Elif
• For Loop
• While Loop
• Breaking Out of Loops
• The pass Statement

Functions

• What is Scope?
• Functions & Arguments
  • Positional Arguments
  • Keyword Arguments

 

More Advanced Python

Exceptions

• What are Exceptions?
• Catching Exceptions
• Try/Finally Statement

Working with Files and Directories

• Open
• Modes
• With Statement

Complex Data Structures

• How to think about Data
• Examples:
  • A list of Lists
  • A List of Dictionaries
  • A Dictionary of Dictionaries

Maintaining State

• Data Serialization
  • XML (Mid 90s)
  • YAML (2001)
  • JSON (early 2000s)
  • Pickle
  • Database

Modules

• Finding and Using Modules
• Creating your own Modules
• Namespaces :: Cautionary Tale

 

Labs

Lab 1

• Virtual Env & Packet Manager

Lab 2

• VS Code Remote Development Environment

Lab 3

• Ping to multiple hosts with subprocess call

NETMIKO

• Lab 4 - Basic Connections
  • Clock Output
  • Show interface brief
• Lab 5 - Netmiko send configs
  • Option 1 - Send Commands to single device
  • Option 2 - Getpass
  • Option 3 - Send Command Sets to single device
  • Option 4 - Time Library
  • Option 5 - Connect to multiple devices and assign unique IP address to VLAN 10
  • Option 6 - Netmiko Exception Handling
• Lab 6
  • Json
• Lab 7
  • Config Backup