buildpack: R

This buildpack downloads and installs R into a Scalingo app image.

Using this buildpack

The following instructions should get you started:

Initialize a new git repository wherever you want:

% mkdir my-r-app
% cd my-r-app
% git init

Create the Scalingo app:

% scalingo create my-r-app

Add some R packages, if needed.
Deploy:

% git push scalingo master

Start a console one-off:

(This will only work if you have a console process type defined in your Procfile.)

scalingo --app my-r-app run --type console

Understanding this buildpack

Detection

The platform considers the app as a R app if:

a file called run.R, app.R, plumber.R, init.R or R-packages exists at the root of your project.

Warning
The platform only installs R. If you need a specific framework such as plumber or shiny, you still have to ask the buildpack to install it.

Deployment workflow

During the BUILD phase, this buildpack:

Downloads R if necessary (when the requested version is not in cache).
Compiles and installs R with the following options:
- --enable-java=no
- --enable-recommended-packages=no
- --enable-R-shlib=yes
- --without-x
Downloads and installs the requested R packages, if any.
Validates the build.

🎉 This process results into a scalable image that includes the configuration, ready to be packaged into a container.

Release

By default, the release script creates a console process type which is (currently) ignored by Scalingo.

If you need this console process type, add a Procfile at the root of your project and add the console process type:

console: R --no-save

Moreover, if a file called run.R, app.R or plumber.R exists at the root of the project, the release script also creates a web process type with the following command:

R --file=${HOME}/{run,app,plumber}.R --gui-none --no-save

Consequently:

if you don't need the web process type, make sure to scale it to zero:
```
scalingo --app -my-r-app scale web:0
```
if you need to run another command, add (or update) your Procfile to specify how to start your web process.

Customizing the Build

Installing R packages

The buildpack uses a specific file called R-packages to install R packages.

The R-packages expects one package name per line, with the corresponding version separated by a single space character.

Version can be set to latest or *. It can also be omitted, in which case it will be interpreted as latest.

Warning
Due to R internals, there are 2 ways of installing a package:

If you chose to install the latest version of a package, R is able to automatically download and install it, along with its dependencies.

If you need a specific version of a package, R is not able to automatically download and install its dependencies. You will have to ask the buildpack to install each dependency in the appropriate order.

For example, the following R-packages file...

rlang 1.0.2
ellipsis *
fansi latest
shiny

...will result in the following actions:

The buildpack will download and install rlang 1.0.2,
it will automatically install the latest version of ellipsis (this package depends on rlang, previously installed),
it will automatically install the latest version of fansi (this package depends on grDevices and utils, installed with R),
it will automatically install all shiny dependencies and then the latest version of shiny.

Note: when a specific version of a package is required (i.e. not latest), the buildpack tries to keep the compiled package in cache for future deployments.

Environment

The following environment variables are available for you to tweak your deployment:

`R_VERSION`

Version of R to use.
Defaults to 4.0.0

Frzk/r-buildpack