Configure Travis CI to Deploy Snapshots to a Maven Repo

In order to deal with the amount of different projects Xeiam is currently managing, both open source and commercial, we jumped at the opportunity to move all of our OSS projects over from an in-house Jenkins CI to a free hosted Travis CI service. Doing so frees us up from having to maintain our Jenkins server, deal with it hanging, updating it, etc. This is just one more step in streamlining project development and management. The only disadvantage by doing this was the loss of our Sonar code quality analytics, but I suspect something of the sort will soon become available as a plugin to Travis CI.

What we needed Travis CI to do though was a bit non-standard, and we wanted to write what we learned here for future reference, but also to help other get their Maven builds deploying snapshots to a repository. This article assumes you've already setup your Travis CI account and have followed the standard setup procedures and configurations linking your Travis CI and GitHub accounts and projects. Make sure to enable the Travis CI hook in GitHub too. The example configurations contain stuff relevant to our project XChart, and you'll have to adapt your configurations to your specific project's properties.

References

Our initial inquiry on Travis Google group
Travis gem and secure variables
Xeiam's XChart project on GitHub
XChart's Travis CI page

settings.xml

Simply add another branch to your project called `travis`, remove everything from it, and place the following `settings.xml` file in it.

<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0
                      http://maven.apache.org/xsd/settings-1.0.0.xsd">
  <localRepository/>
  <interactiveMode/>
  <usePluginRegistry/>
  <offline/>
  <pluginGroups/>
  <servers>
    <server>
      <id>sonatype-nexus-snapshots</id>
      <username>${env.CI_DEPLOY_USERNAME}</username>
      <password>${env.CI_DEPLOY_PASSWORD}</password>
    </server>
  </servers>
  <mirrors/>
  <proxies/>
  <profiles/>
  <activeProfiles/>
</settings>

Generate Encrypted Variables

The artifact repo requires a username and password of course, and we don't want to have those as plain-text in the above `settings.xml` file. Therefore we use the following commands to generated the encrypted keys. You'll need to run these commands on a machine where ruby is installed and the travis gem is installed. Obviously replace `timmolter/XChart` with your own github account name and project name.

travis encrypt -r timmolter/XChart "CI_DEPLOY_USERNAME=username"
travis encrypt -r timmolter/XChart "CI_DEPLOY_PASSWORD=password"

.travis.yml

Place a file called `.travis.yml in the root of the project on the branch you want to be deployed. You'll need to modify this .travis.yml file as shown here. The whitelist specifies that we only want the build to run on the `develop` branch. Replace the keys below with your generated codes from the previous step.

language: java
before_install: "git clone -b travis `git config --get remote.origin.url` target/travis"
script: "mvn deploy --settings target/travis/settings.xml"

# whitelist
branches:
  only:
    - develop

env:
  global:
    - secure: "R7i6miE4AIbj1o6E8fwWvKwjvygha172QSdKM0Jto/Qq3AyLuWMCthYAxevq\nX+I64lw3exhmEiOHXHjh1lGTnGZ9kXklIU+q4vo9QfdYH7WU47chE0KZfQtd\n64EoFo8KmSD4VQjyiNv7ReLdoqksRAj2dL386fWrBAUWkwhxD4w="
    - secure: "UL4rCDPPBrk7cju9f+fNi1qfGWb+q/36wJYUEeuINDa2a4c4oHvdOX0aYOIV\nbBDeaReKMtl6mpjG2uxCZwaz7N3/VADDMrqA+wbTbWKgyWeTACzAz/Z/6w8E\noOAkS8EUCZgDiXeHuirYvQQ47KbzYmf2m4/EUAQm+VIHFbO1ssE="

Test It

Now that everything is setup, all you need to do is push a change on the `develop` branch to GitHub, and Travis CI will build the Maven project and deploy the artifacts to a snapshot repo automatically!

Piece of Cake!!!

Other Travis CI Tidbits

1. Pushes that have [ci skip] anywhere in one of the commit messages will be ignored.
2. Embed a Travis CI build badge in REAME.md file: `[](https://travis-ci.org/timmolter/XChart.png?branch=develop)`