Drupal Core Metrics

A dashboard that tracks Drupal core's codebase over time: lines of code, complexity, maintainability, anti-patterns, and API surface area.

View the dashboard: https://dbuytaert.github.io/drupal-core-metrics/

Learn more: Measuring Drupal Core code complexity

Metrics

Code quality

• SLOC: Source lines of code (excluding blanks and comments)
• Cyclomatic complexity: Decision paths in code. Lower is simpler.
• Maintainability index: 0-100 score. Higher is easier to maintain.

Anti-patterns

Code patterns with known downsides. Tracked per 1k lines.

Pattern	Description
Magic keys	#-prefixed array keys. Inherent to Drupal's render array architecture.
Deep arrays	3+ levels of nesting. Hard to read and refactor.
Service locators	\Drupal::service() calls. Hides dependencies, hinders testing.

API surface area

Distinct extension points in Drupal. A larger surface may correlate with a steeper learning curve.

Category	Examples
Plugin types	Block, Field, ViewsDisplay
Hooks	hook_form_alter, hook_entity_presave
Magic keys	#theme, #states, #ajax (vocabulary size)
Events	KernelEvents::REQUEST
Services	cache, entity, router
YAML formats	routing, permissions, services

Running locally

Prerequisites: PHP 8.1+, Python 3, Composer

Regenerating data

composer install              # Install dependencies
python3 scripts/analyze.py    # Run analysis (15-30 min)

This generates data.json. The index.html file is static and does not need to be regenerated.

Viewing the dashboard

The dashboard loads data via fetch(), which requires an HTTP server (browsers block this for local files). Start a simple server:

python3 -m http.server 8000

Then open http://localhost:8000 in your browser.

Contributing

Questions or ideas? Open an issue or PR.