webr-package-repo-demo

Can we build and serve webr packages?

This demo includes several R packages used in the OU module M348 in the packages directory that are compiled to Wasm packages by the Github Action, then published to a CRAN style repo.

Adding and Building New Packages

Add references to packages that need to be built to the .github/workflows/test-package_build.yml file:

• if package source is provided (.tar.gz), put the .tar.gz source file in ./packages and refer to as local::./packages/PACKAGE.tar.gz in the .yml file
• for packages on CRAN, just give the package name (e.g. jsonlite)

In the .github/workflows/test-package_build.yml file:, specify the R version via the webr-image: parameter (eg webr-image:"ghcr.io/r-wasm/webr:v0.3.3").

Build using the Build M348 deployment packages action. The files are published as a repo via GitHub pages and also uploaded as an artefact to the action run report page (the artefact download link expires after a certain number of days.)

Accessing the Repo

The packages manifest can be found at:

https://ouseful-testing.github.io/webr-package-repo-demo/src/bin/emscripten/contrib/4.3/PACKAGES.rds (link downlads RDS file)

Packages can then be installed as:

install.packages("M348", repos="https://ouseful-testing.github.io/webr-package-repo-demo/src/contrib")

If there is a JupyterLite webr kernel mismatch, an error will be generated:

So we need to build the package for the correct version of R. The default version is set in .github/workflows/test-package_build.yaml eg as per webr-image: "ghcr.io/r-wasm/webr:main" which is currently at "ghcr.io/r-wasm/webr:v0.4.1"; to build for the 4.3 kernel used by the current webr jupyterlite kernel, we need to set: webr-image: "ghcr.io/r-wasm/webr:v0.3.3"

We scan set the path directly in the calling action, e.g. in .github/workflows/deploy-cran-repo.yml:

webr-image:
  description: Docker container image for webR development environment. Defaults to the latest version of webR.
  default: ghcr.io/r-wasm/webr:v0.3.3 #Original default: "ghcr.io/r-wasm/webr:main", currently at v0.4.1

For the current jupyterlite kernel, we need "ghcr.io/r-wasm/webr:v0.3.3"

In use, when writing R code, the webR library() function appears to pre-emptively try to install a missing package from the webR repo.

Setting options(webr_pkg_repos= "https://github.com/ouseful-testing/webr-package-repo-demo") should force install.packages() and the library() function to pull packages from the package repository published using GitHub Pages from this repository.

If we copy the repository files into a /repo directory in a JupyterLite deployment site (eg rooted on https://ouseful-demos.github.io/jupyterlite-m348-demo/), we can set options(webr_pkg_repos= "https://ouseful-demos.github.io/jupyterlite-m348-demo/repo/") and then the packages will be pulled from the same domain as JupyterLite distribution.

If we build our own webR release, we can presumably set that path via the webr-image.default value in the action YAML, although I'm not sure what URL the actual resource needs to be on?