• Drat is a useful little package, for, inter-alia, using github gh-pages as an R repository
• Travis is a hosted continuous integration service. It is integrated with gitHub and offers first class support for a number of languages, but importantly, R.

This package illustrates how to automatically update a drat github repository, on a successful travis build.

1. Set up a drat repo

2. Add travis support to your package

3. Get a github API token to generate a new Personal access token. You might need to re-enter your password. Just select repo, or if your repository is public, you can select public_repo instead. GitHub will create the token and give you a chance to copy it down.

4. Travis will need to encrypt this token. The short story is:

# Install Ruby first. Will probably require sudo
gem install travis

If sudo isn't available, you can do a local install

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

1. 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. Copy across deploy.sh and edit appropriately.
2. Add the line

after_success:
  - test $TRAVIS_REPO_SLUG == "csgillespie/dratTravis" && 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
- if the commit is on the master you own, i.e. USERNAME/dratTRAVIS
- not for pull requests
- only on the master branch

1. The bash script is a bit hacky.
2. It should be possible to only update if a version is tagged. Travis provides a variable $TRAVIS_TAG, that is empty if the commit isn't a tag. But when tagging, $TRAVIS_BRANCH also changes to the tag name.