Building a Ruby Project

What This Guide Covers #

Language versions and other build-environment specific information are in our reference pages:

The rest of this guide covers configuring Ruby projects on Travis CI. If you’re new to Travis CI please read our Tutorial and build configuration guides first.

Specifying Ruby versions and implementations #

The Ruby environment on Travis CI uses RVM to provide many Ruby implementations, versions and even patch levels.

To specify them, use the rvm: key in your .travis.yml file:

language: ruby
  - 2.2
  - jruby
  - truffleruby
  - 2.0.0-p247

Note that the rvm: key is only available in Ruby Build Environments, not in other images containing a ruby implementation.

As we upgrade both RVM and Rubies, aliases like 2.2 or jruby point to different exact versions and patch levels.

Using .ruby-version #

If the ruby version is not specified by the rvm key, Travis CI uses the version specified in the .ruby-version file in the root of the repository if one is available.

Rubinius #

If you’re using macOS or Trusty environments, you can also use Rubinius. To test with Rubinius, add rbx-X or rbx-X.Y.Z to your .travis.yml, where X.Y.Z specifies a Rubinius release listed on .

language: ruby
dist: trusty
  - rbx-3

TruffleRuby #

To test with TruffleRuby, simply add truffleruby or truffleruby-VERSION to your .travis.yml:

language: ruby
  - truffleruby # latest release
  # or
  - truffleruby-1.0.0-rc9 # specific version

See the TruffleRuby releases page for a list of release versions. Please file any issues on GitHub.

JRuby: C extensions are not supported #

Please note that C extensions are not supported in JRuby on Travis CI. The reason for doing so is to bring it to developers attention that their project may have dependencies that should not be used on JRuby in production. Using C extensions on JRuby is technically possible but is not a good idea performance and stability-wise and we believe continuous integration services like Travis CI should highlight it.

So if you want to run CI against JRuby, please check that your Gemfile takes JRuby into account. Most popular C extensions these days also have Java implementations (json gem, nokogiri, eventmachine, bson gem) or Java alternatives (like JDBC-based drivers for MySQL, PostgreSQL and so on).

Default Build Script #

On Ruby projects the default build script is rake. Add rake to the :test group of your Gemfile.

Dependency Management #

Bundler #

Travis CI uses Bundler to install your Ruby project’s dependencies if there is a Gemfile in the project’s root directory, or if there is a Gemfile specified in the build matrix:

bundle install --jobs=3 --retry=3

If a Gemfile.lock exists in your project’s root directory, we add the --deployment flag.

If you want to use a different means of handling your Ruby project’s dependencies, you can override the install command.

install: gem install rails

By default, gems are installed into vendor/bundle in your project’s root directory.

Bundler 2.0 #

On January 3rd 2019 the Bundler team released Bundler 2.0 which dropped support for Ruby versions 2.2 and older, and added a new dependency on RubyGems 3.0.0. A subsequent release, 2.0.1, requires RubyGems 2.5.0.

Under many configurations, Travis CI installs the Ruby runtime on the fly. This means installing the latest Bundler at run time, which may cause problems due to the unsatisfied requirements.

If you find your builds are failing due to “bundler not installed” errors, try one of the following solutions:

  • If you’re using Ruby 2.3 or higher, and you wish to upgrade to Bundler 2.0, use the following in your .travis.yml to update RubyGems:

        - gem update --system
        - gem install bundler
  • If you are using Ruby 2.3.x but wish to stay on Bundler 1.x (e.g., for dependency reasons such as Rails 4.2.x), write:

        - gem uninstall -v '>= 2' -i $(rvm gemdir)@global -ax bundler || true
        - gem install bundler -v '< 2'

    The gem uninstall command above removes any Bundler 2.x installed in RVM’s “global” gemset during the Ruby run time installation, which would be selected as the default bundle command. We ignore the failure from that command, because the failure most likely means that there was no matching Bundler version to uninstall.

Your build configuration may require a combination of these workarounds.

Caching Bundler #

Bundler installation can take a while, slowing down your build. You can tell Travis CI to cache the installed bundle.

On your first build, we warm the cache. On the second one, we’ll pull in the cache, making bundle install only take seconds to run.

Speeding up your build by excluding non-essential dependencies #

Lots of project include libraries like ruby-debug, unicorn or newrelic_rpm in their default set of gems.

This slows down the installation process quite a lot, and commonly, those libraries aren’t needed when running your tests. This also includes libraries that compile native code, slowing down the installation and overall test times even more.

On top of that, libraries that implicitly pull in ruby_core_source or linecache19, are bound to fail when Travis CI upgrades Ruby versions and patchlevels.

The same is true for gems that you only need in production, like Unicorn, the New Relic library, and the like.

You can speed up your installation process by moving these libraries to a separate section in your Gemfile, e.g. production:

group :production do
  gem 'unicorn'
  gem 'newrelic_rpm'

Adjust your Bundler arguments to explicitly exclude this group:

bundler_args: --without production

Enjoy a faster build, which is also less prone to compilation problems.

Custom Bundler arguments and Gemfile locations #

The default Gemfile location is the Gemfile in the root of your project.

To specify a custom Gemfile name or location:

gemfile: gemfiles/

If you specify the location of your Gemfile in this way, the build will fail if the file is not found.

You can pass extra arguments to bundle install:

bundler_args: --binstubs

Testing against multiple versions of dependencies #

Many projects need to be tested against multiple versions of Rack, EventMachine, HAML, Sinatra, Ruby on Rails,etc.

To test against multiple versions of dependencies:

  1. Create a directory in your project’s repository root where you will keep gemfiles, such as ./gemfiles.
  2. Add one or more gemfiles to it.
  3. Set the gemfile key in your .travis.yml.

Thoughtbot’s Paperclip is tested against multiple ActiveRecord versions:

  - gemfiles/rails2.gemfile
  - gemfiles/rails3.gemfile
  - gemfiles/rails3_1.gemfile

An alternative to this is to use environment variables and make your test runner use them. For example, Sinatra is tested against multiple Tilt and Rack versions:

  - "rack=1.3.4"
  - "rack=master"
  - "tilt=1.3.3"
  - "tilt=master"

ChefSpec is tested against multiple Chef versions:

  - CHEF_VERSION=14.3.37
  - CHEF_VERSION=13.10.0
  - CHEF_VERSION=12.22.5

The same technique is often applied to test against multiple databases, templating engines, hosted service providers and so on.

$BUNDLE_GEMFILE environment variable #

When gemfile is defined and a Gemfile file exists in the repository, we define the environment variable $BUNDLE_GEMFILE, which bundle install uses to resolve dependencies.

If you need to work with multiple Gemfiles within a single job, override $BUNDLE_GEMFILE by passing the --gemfile= flag:

bundle install --gemfile=my_gemfile

JRuby: Testing against multiple JDKs #

Test projects against multiple JDKs, by using the jdk key in your .travis.yml:

  - oraclejdk7
  - openjdk7
  - oraclejdk8

Each JDK you test against will create permutations with all other configurations, so to avoid running tests for, say, CRuby 1.9.3 multiple times you need to add some matrix excludes (described in our Build Configuration guide):

language: ruby
  - 1.9.2
  - jruby-18mode
  - jruby-19mode
  - jruby-head
  - openjdk6
  - openjdk7
  - oraclejdk7
    - rvm: 1.9.2
      jdk: openjdk6
    - rvm: 1.9.2
      jdk: openjdk7
    - rvm: 1.9.2
      jdk: oraclejdk7

For example, see travis-support.

Using Java 10 and Up #

For testing with OpenJDK and OracleJDK 10 and up, see Java documentation.

Upgrading RubyGems #

The RubyGems version installed on Travis CI’s Ruby environment depends on what’s installed by the newest Bundler/RubyGems combination, and is kept as up-to-date as possible.

Should you require the latest version of RubyGems, you can add the following to your .travis.yml:

  - gem update --system
  - gem --version

To downgrade to a specific version of RubyGems:

  - gem update --system 2.1.11
  - gem --version

Note that this will impact your overall test time, as additional network downloads and installations are required.