Add option to build on Linux R-devel

[pat-s]

Currently selecting - { os: ubuntu-18.04, r: "release" } fails with

Run r-lib/actions/setup-r@master
##[error]Node run failed with exit code 1

[pat-s]

Your most likely aware that R-devel builds can be get as a tarball via https://stat.ethz.ch/R/daily/.

There is a even some code in the installer that should throw a descriptive error when R-devel is requested but it seems not to work:

actions/setup-r/src/installer.ts

Lines 346 to 349 in 52d876c

	function getDownloadUrlUbuntu(filename: string): string {
	if (filename == "devel") {
	throw new Error("R-devel not currently available on ubuntu!");
	}

All other install funs use "version" as the argument, the ubuntu one filename - could that be the problem?

Could you shine a bit light on why R-devel is not supported on the Linux Runners currently? Don't wanna go down a potential rabbit hole 😄

[jimhester]

Because in order to support it we would have to build daily binaries for it. Those tarballs are just the daily source, not binaries.

[pat-s]

The availability of binaries as the restriction for the lack of the R-devel installer itself seems odd. Wouldn't this also apply to macOS then for which R-devel is available?

To build upon r-lib/actions it would be great if the availability of the R-devel installer is not a constraint of the availability of package binaries.
One might prefer source installations, especially on R-devel (where compilers might be different than for R-release).

[jimhester]

There are daily R-devel binaries for macOS which is what is used, so no it does not apply to macOS.

Installing R from source requires a different set of system dependencies than installing R packages, it is out of scope for the setup-r action. I have no interest in supporting it.

At some point in the future https://github.com/rstudio/r-builds will supply daily linux binaries for R-devel and when that happens they will be supported in the setup-r action. Until that time R-devel will not be available on linux through the setup-r action.

[pat-s]

As of https://github.com/travis-ci/travis-build/blob/0afb532b33b76d11c0ec308639f935dd458c596f/lib/travis/build/script/r.rb#L103-L108.

the following is done on Travis for R-devel

$ curl -fLo /tmp/R-devel-$(lsb_release -cs).xz https://travis-ci.rstudio.org/R-devel-$(lsb_release -cs).xz

$ tar xJf /tmp/R-devel-$(lsb_release -cs).xz -C ~

$ rm /tmp/R-devel-$(lsb_release -cs).xz

$ sudo mkdir -p /usr/local/lib/R/site-library $R_LIBS_USER

$ sudo chmod 2777 /usr/local/lib/R /usr/local/lib/R/site-library $R_LIBS_USER

which I think you coded yourself or at least contributed.

Why is the same approach not an option on Github Actions?
Or in the other words: What is wrong with the R-devel builds used on Travis so that they cannot be used in GHA?

[jimhester]

Because those binaries are built on travis and assume travis' default system dependencies, which are different on GitHub Actions.

[yutannihilation]

@jeroen
Sorry for bothering you. I feel your great work https://github.com/r-devel/r-svn/ can be used for this somehow. It doesn't include Ubuntu, but I guess it's not very difficult to add as Debian is already there (Or, maybe is it easier for us to switch to Debian...?). What do you think?

[jimhester]

Daily R-devel builds are now supported (23635c0)