airship/pegleg
Code Issues Proposed changes
pegleg/doc/source/developer-overview.rst
Felipe Monteiro adb23bc2a6 docs: Add developer overview guide 
This patch set introduces a developer overview documentation
page to Pegleg to help developers onboard.

Change-Id: Ia453d76f024db39c6bdd97a44bfe1db1c25193f9
2018-09-13 18:28:58 -06:00

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Developer Overview of Pegleg

Pegleg's core mission is to, alongside Deckhand, facilitate document authoring strategies within Airship, by:

  • aggregating documents across multiple revisioned repositories, each of which contains multiple documents defining sites' software and hardware stacks
  • providing early linting of documents prior to their collection and eventual deployment
  • including utility functions enabling operators and developers alike to list available sites, render individual manifests via Deckhand, bootstrap repositories with Pegleg-compliant directory layouts, to name a few

Architecture

Pegleg, as a CLI, has a rather simplistic architecture. It is meaningful to visualize Pegleg alongside Deckhand:

High level architecture of Pegleg + Deckhand

Components

cli

The Pegleg cli module implements the user-facing CLI. For more information about this module, reference the CLI documentation <pegleg-cli>.

engine

The engine module implements the following functionality:

  • document linting
  • document rendering via Deckhand
  • document aggregation
  • additional document utility functions

Developer Workflow

Because Airship is a container-centric platform, the developer workflow heavily utilizes containers for testing and publishing. It also requires Pegleg to produce multiple artifacts that are related, but separate: the Python package, the Docker image and the Helm chart. The code is published via the Docker image artifact.

Pegleg strives to conform to the Airship coding conventions.

Python

The Pegleg code base lives under /src/bin/pegleg. Pegleg supports py35 interpreters.

Docker

The Pegleg Dockerfile is located in /images/pegleg along with any artifacts built specifically to enable the container image. Make targets are used for generating and testing the artifacts.

  • make images - Build the Pegleg Docker image.

Pegleg, as a containerized CLI, uses Docker via tools/pegleg.sh to execute CLI commands. Commands can also be executed using the Makefile target: run_pegleg.

Testing

All Pegleg tests are nested under /src/bin/pegleg/tests.

Pegleg comes equipped with a number of tox targets for running unit tests, as well as pep8 and Bandit checks.