Resolving Maven dependencies from a local p2 repository

February 1, 2016

Warning! If you got here looking for a solution for your own project, think twice, you might be doing it wrong!

The beauty of Maven is, above all, its capabilities to solve dependencies seamlessly from remote artifact repositories. Give your project a URL, a list of plugins and you are good to go. Local dependency is nothing but a burden for your dev colleagues and the Continuous Integration environment.

HOWEVER, let’s say you are working with proprietary libraries from a company that insists to know all about you before you are ever allowed to download and use their API (and don’t forget the “Have a sales representative contact me” checkbox). This API, you guessed, is not available in a Maven repository. Instead, it comes as a compressed p2 repository.

A practical example would be in the Team Concert plugin, more specifically the project com.ibm.team.build.hjplugin-rtc within it.

If you inspect its pom.xml, there are two parts that at least make our life easier by accepting parameters from command line:

Property declaration

<rtc-client-p2repo-url>${env.RTC_Client_p2Repo}</rtc-client-p2repo-url>

Repository declaration

<repository>
    <id>rtc-401</id>
    <layout>p2</layout>
    <url>${rtc-client-p2repo-url}</url>
</repository>

The Maven project above will compile only if a repository is provide via the ${env.RTC_Client_p2Repo} property. Once the p2 repository is decompressed in the local filesystem (i.e. C:\RTC-Client-p2Repo-5.0.1 for Windows), you can compile it as follows:

mvn -Denv.RTC_Client_p2Repo=file:///C:\RTC-Client-p2Repo-5.0.1 clean compile

It’s straightforward, indeed! But the trick is the file:/// prefix that, if missed, won’t be accepted as a <url>.

Done.