Using a Local Repository Server with Gradle

I've been doing a little work with Gradle recently. And one of the things that I find “less than optimal” is that the build script holds far too much knowledge about its environment, which means that you have to jump through some hoops to make those scripts portable. Not a huge problem for in-house development, but if you're making an open-source library, you don't want everyone else to reconfigure their world to match yours.

One particular problem is how to find your dependencies. A typical build script has a repositories section that lists all the places to look. Here's a simple example, that looks first in the local Maven repository, followed by the Maven Central:

repositories {
    mavenLocal()
    mavenCentral()
}

This is a portable build script — although I have no idea how dependencies might find their way to the local Maven repository, since Gradle uses its own dependency cache. A better build script might want to use a local repository server rather than constantly hitting Maven Central:

repositories {
    mavenRepo urls: 'http://intranet.example.com/repository'
}

That works, but now you can't share the build script with anybody else, unless they edit the script to use their own repository server (assuming they have one), and remember not to check in their changes. The solution that I came up with is to store the repository URL in $HOME/.gradle/gradle.properties, which is loaded for every build.

internalRepositoryUrl: http://repo.traffic.com:8081/nexus/content/groups/public/

Then, the build script is configured to add the local server only if the property is defined:

repositories {
    mavenLocal()

    if (project.hasProperty('internalRepositoryUrl') )
        mavenRepo urls: project.internalRepositoryUrl
    else
        mavenCentral()
}

It's portable, but it's ugly. When searching for solutions, I saw a couple of postings indicating that gradle.properties will eventually be allowed to contain expressions as well as properties. That day can't come soon enough.