{sandpaper}: User Interface to The Carpentries Workbench

Universe Codecov test
coverage Lifecycle:
experimental CRAN
status R-CMD-check

The {sandpaper} package was created by The Carpentries to re-imagine our method of creating lesson websites for our workshops. This package will take a series of Markdown or RMarkdown files and generate a static website with the features and styling of The Carpentries lessons including customized layouts and callout blocks. Much of the functionality in this package is inspired by Jenny Bryan’s work with the {usethis} package.


Want to know how this works in a lesson format? Head over to

If, instead, you already know how a lesson is built and are interested in understanding how the functions in {sandpaper} work, you can visit this package documentation site at


{sandpaper} is not currently on CRAN, but it can be installed from our Carpentries Universe (updated every hour) with the following commands:

options(repos = c(
  carpentries = "", 
  CRAN = ""
install.packages("sandpaper", dep = TRUE)

Note that this will also install development versions of the following packages:

| package | What it does | |------------------------------------------------------------|------------------------------------------------------------------------------| | {varnish} | html, css, and javascript templates for The Carpentries (in progress) | | {tinkr} | manipulation of knitr markdown documents built on the commonmark xml library | | {pegboard} | programmatic interface to lesson components for validation (in progress) |


This package is designed to make the life of the lesson contributors and maintainers easier by separating the tools needed to build the site from the user-defined content of the site itself. It will no longer rely on Jekyll or any of the other >450 static site generators, but instead rely on R, RStudio, and {pkgdown} to generate a site with the following features:

Rendering locally

diagram of three folders. The first folder, "episodes/", labelled as RMarkdown, has an arrow (labelled as hash episodes) pointing to "site/built/", labelled as Markdown. The Markdown folder has an arrow (labelled as "apply template") pointing to "site/docs/", labelled as "HTML". The first folder is labelled in pale yellow, indicating that it is the only one tracked by git.The local two-step model of deployment into local folders

In a repository generated via {sandpaper}, only the source is committed to avoid issues surrounding out-of-date artefacts and directory structure confusion.

The website is generated in two steps:

  1. markdown files from the source files are rendered containing a hash for the source file so that these need only be re-rendered when they change.
  2. html files are generated from the rendered markdown files and the CSS and JS sources in the {varnish} package for the preview.

To ensure there are no clashes between minor differences in the user setup, no artifacts are committed to the main branch of the repository. Because of the caching mechanism between the website and the rendered markdown files, long-running lessons can be updated and previewed quickly.

Rendering on continuous integration

Diagrammatic representation of the GitHub deployment cycle showing four branches, gh-pages, md-outputs, main, and my-edit. The my-edit branch is a direct descendent of the main branch, while the gh-pages and md-outputs branches are orphans. Each commit of the main branch has a process represented by a dashed arrow that builds a commit of the subsequent orphan branchesTwo-step deployment model on continuous integration

Continuous integration will act as the single source-of-truth for how the outputs of the lessons are rendered. For this, we want the resulting website to be:

To acheive this, there will be two branches created: md-outputs and gh-pages that will inerit like so main -> md-outputs -> gh-pages. Because the build time from main to md-outputs can be time intensive, this will default to updating only files that were changed.

Scheduled builds

Function syntax

The functions in {sandpaper} have the following prefixes:

Here is a working list of user-facing functions:

Lesson and Episode Creation


Website Creation and Validation

Continuous Integration Utilities



There are five use-cases for {sandpaper}:

  1. Creating lessons
  2. Contributing to lessons
  3. Maintaining lessons
  4. Rendering a portable site
  5. Rendering a site with GitHub actions.

Creating a lesson

To create a lesson with {sandpaper}, use the create_lesson() function:


This will create folder on your desktop called r-intermediate-penguins with the following structure:

|-- .gitignore               # - Ignore everything in the site/ folder
|-- .github/                 # - Scripts used for continuous integration
|   `-- workflows/           #
|       |-- deploy-site.yaml # -   Build the source files on github pages
|       |-- build-md.yaml    # -   Build the markdown files on github pages
|       `-- cron.yaml        # -   reset package cache and test
|-- episodes/                # - PUT YOUR MARKDOWN FILES IN THIS FOLDER
|   |-- data/                # -   Data for your lesson goes here
|   |-- figures/             # -   All static figures and diagrams are here
|   |-- files/               # -   Additional files (e.g. handouts) 
|   `-- 00-introducition.Rmd # -   Lessons start with a two-digit number
|-- instructors/             # - Information for Instructors
|-- learners/                # - Information for Learners
|   `--             # -   setup instructions (REQUIRED)
|-- profiles/                # - Learner and/or Instructor Profiles
|-- site/                    # - This folder is where the rendered markdown files and static site will live
|   `--            # -   placeholder
|-- config.yaml              # - Use this to configure commonly used variables
|--          # - Carpentries Rules for Contributions (REQUIRED)
|--       # - Carpentries Code of Conduct (REQUIRED)
|--               # - Carpentries Licenses (REQUIRED)
`--                # - Introduces folks how to use this lesson and where they can find more information.

Once you have your site set up, you can add your RMarkdown files in the episodes folder. By default, they will be built in alphabetical order, but you can use the set_episodes() command to build the schedule in your config.yaml file:

s <- sandpaper::get_episodes()
sandpaper::set_episodes(order = s, write = TRUE)

When you want to preview your site, use the following:


Working in RStudio?

If you are using RStudio, you can preview the lesson site using the keyboard shortcut ctrl + shift + B (which corresponds to the “Build Website” button in the “Build” tab. To preview individual files, you can use ctrl + shift + K (This corresponds to the “Knit” button in the editor pane)

This will create the website structure inside of the the site/ folder, render the RMarkdown files to markdown (for inspection and quick rendering), render the markdown files to HTML, and then enable a preview within your browser window.

Contributing to a Lesson

To contribute to a lesson, you can either fork the lesson to your own repository and clone it to your computer manually from GitHub, or you can use the {usethis} package to automate it. For example, This is how you can create a copy of Programming With R to your computer’s Desktop.

  repo = "swcarpentry/r-novice-gapminder", 
  destdir = "~/Desktop/r-novice-gampinder",
  fork = TRUE

This will copy all of the source files to your computer and move you to the directory.

Note that the rendered website will not be immediately available. To download the site as it currently appears on the web, use:

sandpaper::fetch_lesson(markdown = TRUE, site = TRUE)

This will download the site and the rendered markdown files into the site/ folder. To save bandwidth, you can choose to just download the markdown files and artifacts by settin site = FALSE. Now, you can edit the Rmarkdown files in episodes/ and quickly render the site.

To upload changes to the lesson repository, you can use the follow

Maintaining a Lesson

When you are maintaining a lesson, there is a high likelihood that you will already have a copy on your machine. If not, follow the instructions in the contributing to a lesson section above.

The typical workflow will look like this:

  1. open the sandpaper project in RStudio and make edits to files in the episodes/ folder
  2. in the R console run the following
sandpaper::check_lesson() # validates the structure of the input files
sandpaper::build_lesson() # builds and validates lesson

Rendering a portable site

To render a portable site, you can follow the instructions for contributing to a lesson or maintaining a lesson to set up. Once you have the lesson set up, you can use the following command:

sandpaper::build_portable_lesson(version = "current")

This will render a fully portable lesson site as a zip file in the site/ folder. You can distribute this lesson to learners who do not have reliable internet access for use offline without sacrificing any of the styling.

Rendering with GitHub actions

Ultimately, there should be a minimal number of functions that handle this situation because writing CI configuration files is maddening. The most straightforward function is:

sandpaper::ci_deploy(md_branch = "md-outputs", site_branch = "gh-pages")

This function will create git worktrees for the orphan md-outputs branch in the site/built folder and the orphan gh-pages branch in the site/docs folder. After that, we generate the site as normal.

Because css and js libraries may need updating before any lesson material does, a step can be created just for rebuilding the site that uses:

sandpaper::ci_build_site(branch = "gh-pages")

When a lesson is given a release, the current site folder needs to be duplicated to a versioned folder and a tag needs to be added to the md-outputs branch:

sandpaper::ci_release(tag = "0.1", md_branch = "md-outputs", site_branch = "gh-pages")

zkamvar/sandpaper documentation built on April 10, 2024, 10:13 a.m.