# Using renv with Continuous Integration

When building, deploying, or testing with continuous integration (CI) systems (e.g. GitHub Actions, Travis CI, AppVeyor, and others), one often needs to download and install a set of R packages before the service can be run. Normally, one will have to download and reinstall these packages on each build, which can often be slow – especially in environments where binary packages are not available from your R package repositories.

`renv` can often be helpful in these situations. The general idea is:

1. Call `renv::snapshot()` on your local machine, to generate `renv.lock`;

2. Call `renv::restore()` on your CI service, to restore the project library from `renv.lock`;

3. Ensure that the project library, as well as the global `renv` cache, are cached by the CI service.

Normally, `renv` will use the R package repositories as encoded in `renv.lock` during restore, and this will override any repositories set in other locations (e.g. in `.Rprofile` or `.Rprofile.site`). We’ll discuss some strategies for providing an alternate R package repository to use during restore below.

## GitHub Actions

When using GitHub Actions, you typically need two steps:

1. Cache any packages installed by `renv`,
2. Use `renv::restore()` to restore packages.

As an example, these steps might look like:

    env:
      RENV_PATHS_ROOT: ~/.local/share/renv

    steps:

    - name: Cache packages
      uses: actions/cache@v1
      with:
        path: ${{ env.RENV_PATHS_ROOT }}
        key: ${{ runner.os }}-renv-${{ hashFiles('**/renv.lock') }}
        restore-keys: |
          ${{ runner.os }}-renv-

    - name: Restore packages
      shell: Rscript {0}
      run: |
        if (!requireNamespace("renv", quietly = TRUE)) install.packages("renv")
        renv::restore()

See also the example on GitHub actions.

## Travis CI

On Travis CI, one can add the following entries to `.travis.yml` to accomplish the above:

    cache:
      directories:
      - $HOME/.local/share/renv
      - $TRAVIS_BUILD_DIR/renv/library

    install:
      - Rscript -e "if (!requireNamespace('renv', quietly = TRUE)) install.packages('renv')"
      - Rscript -e "renv::restore()"

    script:
      - Rscript -e '<your-build-action>'

Note that we provide both `install` and `script` steps, as we want to override the default behaviors provided by Travis for R (which might attempt to install different version of R packages than what is currently encoded in `renv.lock`). See https://docs.travis-ci.com/user/languages/r/#customizing-the-travis-build-steps for more details.

It’s also possible to override the package repository used during restore by setting the `RENV_CONFIG_REPOS_OVERRIDE` environment variable. For example:

    env:
      global:
        - RENV_CONFIG_REPOS_OVERRIDE=<cran>

replacing `<cran>` with your desired R package repository. This can also be accomplished in a similar way by setting:

    options(renv.config.repos.override = <...>)

but it is generally more ergonomic to set the associated environment variable. (See `?config` for more details.) This can be useful if you’d like to, for example, enforce the usage of a MRAN checkpoint during restore, or another similarly-equipped repository.

See https://docs.travis-ci.com/user/caching for more details on how Travis manages caching.

## GitLab CI

The following template can be used as a base when using `renv` with GitLab CI:

    variables:
      RENV_CONFIG_REPOS_OVERRIDE: "http://cran.r-project.org"
      RENV_PATHS_CACHE: ${CI_PROJECT_DIR}/cache
      RENV_PATHS_LIBRARY: ${CI_PROJECT_DIR}/renv/library

    cache:
      key: ${CI_JOB_NAME}
      paths:
        - ${RENV_PATHS_CACHE}
        - ${RENV_PATHS_LIBRARY}

    before_script:
      - < ... other pre-deploy steps ... >
      - Rscript -e "if (!requireNamespace('renv', quietly = TRUE)) install.packages('renv')"
      - Rscript -e "renv::restore()"