CombiningDratAndTravis.md
In drat: 'Drat' R Archive Template

title: "Combining Drat and Travis CI" author: "Colin Gillespie and Dirk Eddelbuettel" date: "Written 2015-04-14, updated 2021-03-29" css: "water.css"

Travis CI is a hosted continuous integration service. It is integrated with GitHub and offers first class support for a number of languages, but importantly for us, R. Travis CI enables package authors to continually ensure their package always build and passes associated unit tests.

Whenever a commit is pushed to a git repository that contains an R package, Travis CI attempts to build the associated R package (see r-travis for R specific examples). This ensures the repository always contains a working package. This vignette describes a modification to the standard Travis CI workflow. If a package build is successful, the package is then pushed to a drat repository.

Unsurprisingly in order to integrate Travis CI with drat, you must first to have a drat repository and secondly add Travis CI support to that repository.

To allow Travis CI to push to your GitHub repository, we need to generate a GitHub API token. After re-entering your password, just select repo, or if your repository is public, select public_repo. GitHub will create the token and give you a chance to copy it down.
Travis CI will then encrypt this token. The short story is:

# Install Ruby first. This may require sudo
gem install travis

If sudo is not available, you can do a local install

# Look at ~/.gem/
gem install --user-install travis

cd to the R package directory and run

travis encrypt GH_TOKEN=$MY_ACCESS_TOKEN --add env.global

where $MY_ACCESS_TOKEN is your access token. The --add env.global automatically adds the token to your .travis.yml file. 1. Add the deploy.sh shell script to your repository and edit appropriately. An example is found at the end of this vignette and also in the dratTravis repository.

Add the lines

    after_success:
      - test $TRAVIS_PULL_REQUEST == "false" && 
        test $TRAVIS_BRANCH == "master" && 
        bash deploy.sh

to your `.travis.yml` file. This means your `drat` repository is only updated
  - for successful builds;
  - only on the master branch;
  - and not for pull requests.

Example `deploy.sh` script

#!/bin/bash
set -o errexit -o nounset
addToDrat(){
  PKG_REPO=$PWD

  cd ..; mkdir drat; cd drat

  ## Set up Repo parameters
  git init
  git config user.name "XXX YYY"
  git config user.email "XXXX@example.com"
  git config --global push.default simple

  ## Get drat repo
  git remote add upstream "https://$GH_TOKEN@github.com/GITHUB_USERNAME/drat.git"
  git fetch upstream 2>err.txt
  git checkout gh-pages

  Rscript -e "drat::insertPackage('$PKG_REPO/$PKG_TARBALL', \
    repodir = '.', \
    commit='Travis update: build $TRAVIS_BUILD_NUMBER')"
  git push 2> /tmp/err.txt

}
addToDrat

If you use a docs/ directory in the main branch, omit git checkout gh-pages and use cd docs instead.