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This tutorial contains notes about Travis CI.

1. Travis CI

Travis CI is a really easy to use build server for projects hosted on GitHub, where the projects easily can be tested and deployed. Even pull requests (PRs) can be built automatically with Travis CI.

It is available here: https://travis-ci.org/

For Open Source projects on GitHub the Travis CI service is for free.

2. Setup

Go to https://travis-ci.org/ and press the Sign Up or Sign in with GitHub button.

travis ci signup

Once the Sign Up button has been pressed a redirection to GitHub will take place in order to authorize Travis CI as application.

authorize travis ci

Press Authorize application to authorize Travis CI, confirm this with your password and Travis CI will check which repositories are available.

Now Travis CI should be listed as application in the settings.

github apps

3. Adding a Repository

Once the setup is done and Travis CI has access to the projects a build can be activated by going to the https://travis-ci.org/profile.

travis ci profile

A certain Repository can be activated by pressing the switch button.

travis ci activate repo

4. .travis.yml Configuration

Travis requires a .travis.yml file to run. As a minimum this file must specify the programming language to be used. For Java, Travis supports Maven and Gradle as build system out of the box.

A minimal .travis.yml file for a Maven or Gradle project looks like the following:

language: java

.travis.yml files can be valided here: http://lint.travis-ci.org/

Supported programming languages can be found here: https://docs.travis-ci.com/user/languages/

A usual .travis.yml file for a Java project, which uses Gradle could look like this:

language: java
# use Java 8
jdk:
- oraclejdk8

# see https://blog.travis-ci.com/2014-12-17-faster-builds-with-container-based-infrastructure
sudo: false

# cache the build tool's caches
cache:
  directories:
  - $HOME/.m2
  - $HOME/.gradle

When a Gradle wrapper is available Travis CI will build your project by using the gradlew build command.

Please ensure to upload all Gradle wrapper files, including the gradle-wrapper.jar file, which might be filtered by the .gitignore file.

5. Triggering a build

How a build can be triggered can be configured in the settings section.

The settings section can be found in the More options  Settings menu.

travis ci repo settings

Here it can be enforced that a .travis.yml file has to be present in order to start a build and whether a build should be triggered at any time a push occurs or even if pull requests come in.

travis ci build trigger

With these options being activated and having a proper .travis.yml configuration simply pushing a new commit is enough to trigger a new build.

The very first build must be be triggered by a git push. Later builds can also be restarted by pressing the Restart build button, which appear after the very first build.

restart build

6. Showing a status icon

To let the users trust in the library the build status determined by Travis CI is often shown in public.

In order to do this simply click on the build status icon and choose from several options for embedding the status icon.

travis ci status icon

In the Status Image dialog a status from a certain branch can be queried.

And besides ASCIIDOC there are many other templates for formats to embed the icon:

  • IMAGE_URL

  • MARKDOWN

  • TEXTILE

  • RDOC

  • ASCIIDOC

  • RST

  • POD

  • CCTRAY

7. Using a display during the build

In order to use and test a UI toolkit during the build xvfb can be used.

It can be activated in the .travis.yml file with the following before_script statement.

# Specify a display with xvfb for UI testing
before_script:
  - "export DISPLAY=:99.0"
  - "sh -e /etc/init.d/xvfb start"
  - sleep 3 # give xvfb some time to start

8. TravisCi resources