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This project is part of The Carpentries Workbench. It serves as a template for Carpentries lessons adapted from {pkgdown}. There is no need to call this package directly, it is installed via the {sandpaper} package.

The html templates use mustache templating language while the CSS and JavaScript are compiled and minified on GitHub Actions.


To install this package, you can use our R-universe repository, which is updated hourly.

install.packages("varnish", repos = "")

There is no need to call this package directly, {sandpaper} will detect it and copy the styling and templates to your lesson website.

CSS and JavaScript

The CSS and JavaScript used for the lessons are minified using SASS and uglifyjs. Their sources live in the source/ folder with directives to include their dependencies (bootstrap, jquery, feather).

The minified versions are built via GitHub actions any time one of the source files is changed.

To build this locally, you need to make sure to have a working version of node and npm, which can be installed via the node version manager, nvm.

Install dependencies

Once you have nvm installed, you can install the node packages locally (they will install in the node_modules/ directory and will be ignored by git) with the following command:

nvm install 16 # make sure we are using node version 16
npm install    # install the packages defined in package.json

Minify CSS and JS

Once you have the dependencies installed, you can run the following scripts to minify the CSS and JS:

bash     # use the sass node module to compile CSS
bash # use the uglifyjs node module to compile JS

HTML Templates

We have customized the following templates:

  • content-chapter displays the episodes for the lessons
  • content-syllabus is the landing page for the lessons
  • content-extra is used for pages that are not chapters and do not need positional navigation
  • [content-overview] is like content-extra, but is meant for the home page of an overview lesson
  • head contains the metadata and script loading
  • navbar is a bit of misnomer, but it contains the sidebar navigation
  • header contains metadata and favicons
  • footer contains navigation, credits, and JSON metadata
  • layout pulls everything together


At the moment, {varnish} uses a mix of global parameters provided in a YAML file generated for {pkgdown} and parameters (both global and page-specific) passed directly to pkgdown::render_page(). All of these parameters are provisioned by {sandpaper}, but it should be noted that this particular structure is expected to change as we move to systems such as quarto, which use pandoc templates.


{pkgdown} provides the {{ #site }}{{ root }}{{ /site }} parameter by default, which inserts the path to the root folder when viewed locally and inserts the URL when viewed on a server.


These parameters are recorded in a workbench lesson under site/_pkgdown.yaml

title: {{ title }} # needed to set the site title
  title: Home
  strip_header: true
  description: ~
  package: varnish
    time: {{ time }}
    source: {{ source }}
    branch: {{ branch }}
    contact: {{ contact }}
    license: {{ license }}
    handout: {{ handout }}
    cp: {{ cp }}
    lc: {{ lc }}
    dc: {{ dc }}
    swc: {{ swc }}
    carpentry: {{ carpentry }}
    carpentry_name: {{ carpentry_name }}
    carpentry_icon: {{ carpentry_icon }}
    life_cycle: {{ life_cycle }}
    pre_alpha: {{ pre_alpha }}
    alpha: {{ alpha }}
    beta: {{ beta }}

Each of these parameters can be accessed via the {{ yaml }} mustache context. For example, this adds a paragraph describing the license provided that the {{ license }} parameter is present in the yaml:

<p>Materials licensed under <a href="{{#site}}{{root}}{{/site}}LICENSE.html">{{license}}</a> by the authors</p>


(TODO: write descriptions of these parameters)


  • {{ instructor }}: a boolean indicating instructor view
  • {{ aio }}: a boolean indicating that the aio page should be included
  • {{ this_page }}: The file-only HTML path of the current page (e.g. index.html or introduction.html).
  • {{{ schedule }}}: The HTML sidebar of the schedule of episodes.
  • {{{ resources }}}: an additional part of the sidebar giving extra resource elements avaialable in mobile view.