Disable Gralde tests when building projects with SAM

Posted on | 176 words | ~1 min
aws sam cloud java gradle

The Serverless Application Model (SAM) allows to easily build, deploy and run serverless applications on AWS. I like the fact that SAM is able to work with Lambda functions that are written in Java and are using Gradle as build tool.

When running sam build to (re-)build any such function, SAM will always do a gradle clean build which includes execution of tests. This makes total sense when running in a CI/CD pipeline. However, during development this will slow down my development process since all test are executed. Failing tests will also prevent sam from finishing the build.

To prevent SAM from running the tests, I added a script to my $HOME/.gradle/init.gradle.kts file:

allprojects {
    tasks.withType(Test::class) {
        onlyIf {
            System.getProperty("software.amazon.aws.lambdabuilders.scratch-dir") == null
                    || System.getenv("GRADLE_SAM_EXECUTE_TEST") != null

This works because SAM sets the system property software.amazon.aws.lambdabuilders.scratch-dir during build. With this script in place I don’t have to do any special modifications to my project. I can even let SAM execute the tests by setting the environment variable GRADLE_SAM_EXECUTE_TEST to any value: