Gradle Pass Configuration on Command Line

Internal

• Gradle Operations
• Gradle Variables and Properties - System Properties

Overview

It is sometimes necessary to pass environment-specific configuration to the build. An example is the URL of a container registry, which may different values relative to the environment the build is executed. The best place for such configuration is not build.gradle, as we would like to avoid editing it for each environment the build is supposed to execute in. One option, which works well for build containers, is to use custom environment variables. Another option is to use command line-specified system properties, as shown below:

gradle -Dmy.environment.dependent.config=blue ...

If not provided on command line, those configuration elements can always fall back to build.gradle hardcoded values.

Playground

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Implementation

We assign the value of the system property to a project extra property, for convenient handling. The same statement is also use to specify a default value, in case the system property is not provided:

ext {
    myEnvironmentDependentConfig = System.getProperty("my.environment.dependent.config", "red");
}

The value can be access as such:

task displayPropertyValueAtExecutionTime {
    doLast {
        println "myEnvironmentDependentConfig: " + myEnvironmentDependentConfig
    }
}

Setting the value on command line results in:

gradle -Dmy.environment.dependent.config=blue displayPropertyValueAtExecutionTime
...
myEnvironmentDependentConfig: blue

Not setting reverts to default:

gradle displayPropertyValueAtExecutionTime
...
myEnvironmentDependentConfig: red