Try to trigger downstream Travis projects from upstream Travis projects hosted on github with a miminum of cluttering your current travis.yml configuration of the upstream project (see prerequisites please).

Consider the following scenario (cf. figure below), i.e. the DOWNSTREAM projects depend on the UPSTREAM project and need to be build if the UPSTREAM project was triggered by a new commit. Therefore we can ensure, if the UPSTREAM project has changed and was tested with success, that the dependent DOWNSTREAM projects are also tested against the changes in the upstream project. This is to make sure that the changes in the UPSTREAM project did really not harm the DOWNSTREAM projects by this given commit.

Please note, if a dependent project has been triggered by our scripts, we log a message in the dependent Travis project (i. e. triggered by upstream project with commit id 1c1234), to make it easy to find the commit of the UPSTREAM project which triggered the current dependent project build and eventually made the DOWNSTREAM project fail.

Consider you have an empty Python upstream project for now, e. g.:

language: 
   - python

python:
   - "2.6"

script:
   -

To trigger a downstream project (either your own or from a different user), e. g. after success of testing, or in general after all your tests have been run, insert this snippet (note you can exchange after_script with for instance after_success, or anything you think should be appropriate for your usecase) into your travis.yml:

before_script:
   - gem install travis

after_script:
   - curl -LO https://raw.github.com/stephanmg/travis-dependent-builds/master/trigger.sh
   - chmod +x trigger.sh
   - ./trigger.sh stephanmg downstream master $TRAVIS_ACCESS_TOKEN 

This results in the following travis yml file:

language: 
   - python

python:
   - "2.6"

before_script:
   - gem install travis

script:
   -

after_script:
   - curl -LO https://raw.github.com/stephanmg/travis-dependent-builds/master/trigger.sh
   - chmod +x trigger.sh
   - ./trigger.sh stephanmg downstream master $TRAVIS_ACCESS_TOKEN 

The first curl statement, fetch the most recent version of the helper scripts trigger.sh from the repository you are currently reading this README. The chmod makes the trigger.sh script executable. The next line actually triggers a downstream project, termed downstream, of the github/travis user stephanmg, if the upstream project uses the master branch then a new build of the corresponding master branch of the downstream project will be scheduled. The TRAVIS_ACCESS_TOKEN is the environement variable actually is your github token which you are supposed to provide in the corresponding downstream travis project you want to trigger (cf. prerequisites below).

1. Token As a prerequisit you need to generate a TOKEN from Github's website, e. g. go to your user profile, navigate to settings, generate an as restrictive as possible TOKEN, and assign it a name, e. g. TRAVIS.
2. Settings Next, navigate to your Travis projects, for instance if your user is stephanmg (github/travis) and your project downstream then go to: https://travis-ci.org/stephanmg/downstream/settings There you need to define a variable, termed e. g. TRAVIS_ACCESS_TOKEN and assign the value of the TOKEN you generated previously. This variable will be available in our travis.yml file by $TRAVIS_ACCESS_TOKEN. This allows you to login passwordless in a e. g. shell script on the travis build environment to your given downstream travis project, and for instance trigger a new build (this could also be a downstream project of a different user, if you know the variable which is used for the TOKEN, e. g. could be different than TRAVIS_ACCESS_TOKEN, and the corresponding username and of course the repository name itself)

• Optionally specify a branch to use
• Optionally multiple trigger statements

In the after_script section you could then have a various of trigger statements, e. g.:

after_script:
   - ./trigger.sh stephanmg downstream master $TRAVIS_ACCESS_TOKEN 
   - ./trigger.sh othergithubuser downstreamProject2 devel $OUR_AGREED_ACCESS_TOKEN_VAR
   - ./trigger ...

• upstream and downstream project branch are assumed to be the same, this could be more flexible, i. e. allow for different branches
• provide a configuration file for the trigger.sh script, i. e. reduce call in your travis.yml file to ./trigger.sh --conf dependent-builds.yml, i. e. storing all relevant information in dependent-builds.yml file.

If you're using a build matrix for your UPSTREAM project, then for each entry you end up with a triggered DOWNSTREAM project. There might be a workaround for this in the future - or if included in the Travis API soon hopefully.

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Travis API documentation