jekyll-minify-flow

This Jekyll plugin uses minify-html to minify rendered HTML pages and documents, and Lightning CSS to minify standalone .css files. Static HTML files without front matter are copied unchanged by Jekyll.

Installation

gem "jekyll-minify-flow", "~> 1.1.0"

Add jekyll-minify-flow to the plugins list in _config.yml:

plugins:
  - jekyll-minify-flow

Configuration

By default the plugin minifies HTML with inline CSS and JavaScript minification enabled. Options can be adjusted by adding a minify_html map to _config.yml; any option set there overrides the defaults. Option names must match the table below and values must be YAML booleans (true or false); invalid configuration stops the build:

minify_html:
  minify_css: true
  minify_js: true
  keep_comments: false

All Cfg options of the pinned minify-html 0.18.1 release are supported:

Option	Default	Description
`minify_css`	`true`	Minify CSS in `<style>` tags and `style` attributes
`minify_js`	`true`	Minify JavaScript in `<script>` tags
`keep_closing_tags`	`false`	Do not omit closing tags when possible
`keep_comments`	`false`	Keep all comments
`keep_html_and_head_opening_tags`	`false`	Do not omit `<html>` and `<head>` opening tags
`keep_input_type_text_attr`	`false`	Keep `type=text` attribute name and value on `<input>` elements
`keep_ssi_comments`	`false`	Keep SSI comments
`minify_doctype`	`false`	Minify DOCTYPEs (may not be spec compliant)
`preserve_brace_template_syntax`	`false`	Pass `{{ }}`, `{# #}`, `{% %}` template code through untouched
`preserve_chevron_percent_template_syntax`	`false`	Pass `<% %>` template code through untouched
`remove_bangs`	`false`	Remove all bangs
`remove_processing_instructions`	`false`	Remove all processing instructions
`allow_noncompliant_unquoted_attribute_values`	`false`	Allow unquoted attribute values prohibited by the WHATWG spec
`allow_optimal_entities`	`false`	Allow entity minifications that may not pass validation
`allow_removing_spaces_between_attributes`	`false`	Allow removing spaces between attributes when possible

Standalone CSS

Every .css file Jekyll writes to the destination — static files as well as .scss sources Jekyll compiled — is minified with Lightning CSS after the site is written. A minify_css map in _config.yml adjusts the behavior (this map is separate from minify_html.minify_css, which only covers CSS embedded in HTML):

minify_css:
  enabled: true
  error_recovery: false
  targets:
    safari: 15.4

Option	Type	Default	Description
`enabled`	`bool`	`true`	Minify standalone `.css` files
`minify`	`bool`	`true`	Print output as small as it goes
`error_recovery`	`bool`	`false`	Carry on past rules that cannot be parsed, instead of failing the build
`targets`	`map`	unset	Browser → oldest supported version (`Integer` for majors, `Float`/`String` for minor versions); unsupported syntax is lowered
`css_modules`	`bool` or `map`	unset	Compile as a CSS module, optionally with a `pattern`
`scope`	`String`	unset	Selector fragment to narrow every rule by

filename is always set to the file being processed so errors and warnings name the right source. Unparseable CSS fails the build with a FatalException naming the file unless error_recovery is enabled.

The plugin runs at page/document post_render, and the CSS pass at site post_write with priority :high, so both run before site post_write hooks such as Fingerprint Flow (priority 12) and Compress Flow (priority 10). Fingerprinting therefore sees rendered, minified HTML and CSS; compression runs after URL rewriting. Jekyll 4.4+ and Ruby 3.3+ are the supported versions.

Development

bundle install
bundle exec rake test          # unit/integration suite (Minitest)
bundle exec rake test:system   # + builds & exercises the packaged gem
bundle exec rake quick         # RuboCop + tests
bundle exec rake               # + bundler-audit

The tests build real Jekyll sites in tmpdirs and assert on the minified output. test/system/ additionally builds the .gem artifact, checks its metadata and packaged file list with Gem::Package, and runs a full jekyll build against the extracted package contents — it catches spec.files gaps that lib-level tests cannot see.

Licensing

This project is a fork of gandaro/jekyll-minify-html-rs. The original code is licensed under the MIT License (see LICENSE.MIT). All new modifications, features, and bug fixes added in this fork are licensed under the GNU Affero General Public License v3.0 or later (see LICENSE).