Specifying remote package dependencies from the r-universe repo

[rempsyc]

My package rempsyc has a remote GitHub dependency on the openxlsx2 package.

My package GitHub actions fail for Windows when building openxlsx2 package from source (Remotes: JanMarvin/openxlsx2 in DESCRIPTION), so the package's author thought of putting the package on the r-universe. In this way, it is already built and should be installed rather easily without leading to failed GitHub action tests.

Now I am wondering how to specify in my own package that the remote dependency is from the r-universe. I have tried the following:

Suggests: 
    [...]
    remotes,
    openxlsx2,
Remotes: 
    r-universe::JanMarvin/openxlsx2

But it fails:

 Error: Error: <callr_remote_error: Cannot install packages:
  * deps::.: Unknown remote type(s): `r-universe`>

Is it even possible to do what I am describing?

[jeroen]

R-universe will automatically add all external dependencies from remotes to your repository. There is nothing you need to do. I see that both xlsx2 and rempsyc are available and passing in your repo: https://rempsyc.r-universe.dev/ui#builds

[rempsyc]

Oh I'm sorry, I just created my r-universe repo because I think the idea is super cool! But the issue is unrelated to my own r-universe repo (it was before I created my own r-universe repo). Rather, I am looking to get rid of the GitHub actions error. If you look at my package readme on GitHub, you will see that the badge is red, indicating failing tests: https://github.com/rempsyc/rempsyc. Actually I can just paste the badge here and it works (nice, even better!):

In order to get rid of the error, I would like GitHub actions to install the other package (openxlsx2) from the r-universe, and my question is essentially about how to specify that in the DESCRIPTION document. I have tried:

Remotes: 
    r-universe::JanMarvin/openxlsx2

But it seems like that is not working, possibly because the remotes package does not recognize the r-universe as a valid repo. So, is it possible to specify the r-universe like above in the DESCRIPTION file for remotes to install it from there? Or is there any other way? Thank you.

Edit: For example, is there any way to specify repo options from within the package itself so that it's picked up automatically by GitHub actions?

options(repos = c(
  rempsyc = 'https://rempsyc.r-universe.dev',
  CRAN = 'https://cloud.r-project.org'))

[rempsyc]

CONFIRMED solution:

actions/setup-r-dependencies at v2 · r-lib/actions · GitHub

Dependencies in other CRAN-like repositories

If your dependency is available in a CRAN-like repository (e.g. R-universe), then you can use the extra-repositories parameter of the setup-r action. See more at the setup-r documentation.

So I had to add the extra-repositories: "https://janmarvin.r-universe.dev" line after with in the - uses: r-lib/actions/setup-r@v2 line, so it looks like this in the R-CMD-check.yaml workflow file:

  - uses: r-lib/actions/setup-r@v2
    with:
      r-version: ${{ matrix.config.r }}
      http-user-agent: ${{ matrix.config.http-user-agent }}
      use-public-rspm: true
      extra-repositories: "https://janmarvin.r-universe.dev"