Hey guys, been looking how to make a fat jar from kotlin, was looking at <this> although its not wor...

# gradle

[André Martins]

Hey guys, been looking how to make a fat jar from kotlin, was looking at this although its not working (im using gradle 7+) any suggestions?

[Emil Kantis]

I’ve been using Shadow for a few years to do this. Ktor docs also suggests using shadow. https://ktor.io/docs/fatjar.html

[André Martins]

ya Ive tried that but somehow it didn’t work

[tapchicoma]

Yes, check shadow plugin

[André Martins]

when I run the jar produced by shadowJar it says mainclass not found 😛

[André Martins]

my build.gradle lookis like this

plugins {
    id 'application'
    id 'kotlin'
    id 'io.gatling.gradle'
    id 'com.github.johnrengelman.shadow'
}

application {
    mainClass = 'io.gatling.app.Gatling'
}

shadowJar {
    manifest {
        attributes 'Main-Class': 'io.gatling.app.Gatling'
    }
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlinVersion"
}

[Emil Kantis]

If Gatling is a file with a main function on file-level (e.g. no class), try io.gatling.app.GatlingKt

[gildor]

How do you build it?

[André Martins]

im using gatling plugin as it is described here

[André Martins]

Without shadow I was trying this way

plugins {
    id 'application'
    id 'kotlin'
    id 'io.gatling.gradle'
}

task fatJar(type: Jar) {
    manifest {
        attributes 'Main-Class': 'io.gatling.app.Gatling'
    }
    from { configurations.implementation.collect { it.isDirectory() ? it : zipTree(it) } }
    with jar
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlinVersion"
}

But i get this error

Resolving dependency configuration 'implementation' is not allowed as it is defined as 'canBeResolved=false'.
  Instead, a resolvable ('canBeResolved=true') dependency configuration that extends 'implementation' should be resolved.

[André Martins]

I suspect it is due to how the gatling plugin gets the dependencies

[Vampire]

My recommendation would be to not buid a fat jar actually.
Fat jars basically only have drawbacks and with Gradle it is super easy to build a proper distribution including a start script you can simply call to execute your project. You are even already applying and configuring the application plugin, you just have to use the distZip or distTar result and you are good to go.
See https://fatjar.net for various quotes.

[ephemient]

it looks like Gatling sets up a separate source set and run configuration, not main, so it's expected that io.gatling.app.Gatling isn't in the main jar or its dependencies