Week 3 recap

Monday

Cookiecutter

• Provides
  • Linting, docstrings & code style
  • Packaging & Dependency Management
  • Docker Container Strategy
  • CLI Application
  • Doc building
  • Testing
  • Execution of builds, testing, etc.
• Tools
  • Cookiecutter – Deliver and re-use the project templates
  • Docker & Docker Compose - Container and containers management
  • Poetry – dependency management and package publishing
  • Invoke – Replacement for Makefiles, used by developers
  • Click – Python CLI application, consumed by users
  • Mkdocs (EM-K-Docs) - docs hosting standard
• Linters
  • Python Black - Used for formatting
  • Bandit - Security enforcement
  • Pylint - Style enforcement
  • Flake8 - Error checking and style enforcement
  • Yamllint - Linter for yaml files
  • Pydocstyle - docstring enforcement
  • Mypy - Static typing
  • Pytest - Python testing framework
• Creation of cookiecutter is to issue cookiecutter to folder
  • Answer a series of questions and it "bakes" the cookie
• Primary mechanism to work with development environment is via invoke commands, such as
  • Build your container
  • Enter the container
  • Run Tests

Workflow Discovery

• Need to understand the workflow before you attempt to automate it
• Often used within the context of a Strategic Architecture, Design Analysis (formerly called an Assessment)
• Collect key metrics
  • How often?
  • How much engineering time?
  • How long to fulfill?
  • Opportunity cost?
• Avoid ambiguity in metrics
• Direct Outcomes
  • Workflow Metrics
  • Diagram and step-by-step description of the Current Workflow
  • Diagram and step-by-step description of the Automated Workflow
  • Workflow recommendations and Analysis
• Indirect outcomes
  • List of all the integrations (SoRs and others) and dependencies
  • Network design reference
  • The key/real stakeholders
  • The value this process being automated will have (useful for prioritization)
  • Uncover institutional and tribal knowledge
  • Validated assumptions about how this process works
  • Reference to acronyms
• Roles within a meeting
  • Driver - drives the conversation
  • Observer - documents the process
  • Copilot - asks clarifying questions
• Each step is
  • An input
  • A process
  • An output
• Helpful link: https://networktocode.atlassian.net/wiki/spaces/AAG/pages/1507229699/Assessment+and+Workflow+Links
• Helpful link: https://drive.google.com/drive/u/0/folders/1DrWyC5AoyoMD0WL67I5evQIBFuvfgvsB

Tuesday

Patterns and Nomenclature

• Imperative - A programming paradigm that uses statements to change a program's state
• Idempotent - An operation is idempotent if performing it multiple times yields the same result as performing it once
• Declarative - A programming paradigm that expresses the logic without describing its control flow
• DRY - A software development principle urging one to reduce repetition of code patterns
• Dispatcher - A method responsible for directing requests or tasks to appropriate handlers or methods based on certain criteria
• Inheritance - A mechanism where a new class derives properties and behaviors (methods) from an existing class
• Principle of Least Astonishment - Design principle stating that a system should behave in a manner consistent with how users expect it to, minimizing their surprise
• Robustness principle (Postel's Law) - Be conservative in what you send, be liberal in what you accept
• State Machine - A computational model designed to be in one of a finite number of states at any given time, transitioning between them based on inputs

Logging Best Practices

• Create an instance of the logging framework
• Leverage the logging levels (debug, info, warning, error, critical) in your logs
• The logging module has constants for each of the logging levels integers, e.g. logging.DEBUG
• Logging supports formats
• Do not f-strings or format in your logs, instead use the % operator

Idempotent

• Mechanism to only make change if not in current state
• Generally completed by checking the current state to see if it is in it's desired state and if so, make no action
• Per REST (RFC 7231) PUT and DELETE are idempotent, PATCH and POST are not.
• Using set theory to build your idempotent logic
• Declarative functions are idempotent, but idempotent commands are not necessarily declarative
• Helpful Link: https://campusnetworkengineering.com/posts/practical-automation-series-part-3/
• Helpful Link: https://blog.networktocode.com/post/Principle-Series-Idempotent/

Wednesday

Declarative

• Describes the end state, not the steps to get there
• Leverages set theory
• Generally solved by getting what is missing and what is extra
• Used in SALT and Terraform
• Is in fact idempotent
• Helpful Link: https://blog.networktocode.com/post/Principle-Declarative-Imperative/

Dispatcher

• Dispatcher directs tasks, calls, or requests based on certain criteria
• Generally many if-else statements indicate a dispatcher idea
• Dictionary mapping the function object to be callable at run time
• Have to consider function signature, but can send in kwargs
• Easier to be explicit and map everything
• Reviewed import_string and how to use a dispatcher with that

Inheritance

• Great for reusability of code
• Great to extend existing code
• Can override methods in Python classes
• Can still call parent class with super on any method
• Be considerate about where super is called
• Concept is not limited to Python classes, used in Ansible variable structure, Nautobot Config Context, etc.
• Helpful Link: https://blog.networktocode.com/post/Principle-Series-Inhertiance/

Thursday

Friday