Can Gradle fail the build if the jar is too big? - gradle

Question

What is a good way for gradle to warn the developer that the code/dependency change they’re making makes the built jar too big?
We’re making updates to a repo that builds a jar that’s deployed in an AWS Lambda function. We are limited to 50MB for the executable. We’d ideally like the devs to get this feedback much before our CI/CD tries to upload to a lambda function and fails.

Answer 1

You could define and use a custom task to implement the file size check, and create a dependency between this task and the task that produces the Jar.
Assuming you are using Sprinboot, you could create a finalizer task that will be executed just after the bootJar task and make the build fail when jar size exceeds a certain limit.
Simple implementation as example:
task jarSizeChecker() {
def maxSize = 15_000_000 // jar size limit in bytes
group "verification"
description "Checks that the produced jar size does not exceed the defined limit"
doLast {
println " checking jar size"
def jarFileSize = bootJar.archiveFile.get().getAsFile().length()
println " fileSize is ${jarFileSize}"
if (jarFileSize > maxSize) {
throw new GradleException("Jar size exceed the defined limit")
}
}
}
bootJar.finalizedBy(jarSizeChecker)
Result:
$ ./gradlew bootJar
[...]
> Task :bootJar
> Task :jarSizeChecker FAILED
checking jar size
fileSize is 17333895
7 actionable tasks: 5 executed, 2 from cache
FAILURE: Build failed with an exception.
* Where:
Build file 'C:\dev\workspaces\...\build.gradle'
* What went wrong:
Execution failed for task ':jarSizeChecker'.
> Jar size exceed the defined limit