Is there a guide on building a linux x64 native li...

# gradle

[sean]

Is there a guide on building a linux x64 native lib via kts? I want this to be inherited by another external project. My searching has not been helping much. I'm getting the following error. I've tried spinning up a source set nativeMain, but getting that doesn't exist.

- Required org.jetbrains.kotlin.platform.type 'native' and found incompatible value 'common'.

[napperley]

Have a look at the Building Multiplatform Projects with Gradle article (covers Gradle Kotlin DSL - https://kotlinlang.org/docs/reference/building-mpp-with-gradle.html ). Although the article isn't Linux specific it should point you in the right direction. I recommend reading through the Setting up Targets section ( https://kotlinlang.org/docs/reference/building-mpp-with-gradle.html#setting-up-targets ).

[napperley]

Here is a build file which shows how to publish a Kotlin Native library which targets linuxX64: https://gitlab.com/gui-vista/guivista-core/blob/master/build.gradle.kts

[napperley]

The linuxX64 target is the easiest Kotlin Native target to get started with. Reasonably straightforward to setup a Linux program/library quickly.

[sean]

Thanks for the links
I have a linux Target

linuxX64 {
        val main by compilations.getting
        binaries {}
        compilations.getByName("main") {
            cinterops.create("zfLog") {
                defFile = File("$projectDir/src/linuxX64Main/nativeInterop/cinterop/zLog.def")
                includeDirs("$projectDir/src/linuxX64Main/nativeInterop/zLog")
            }
        }
    }

Then a source set

val linuxX64Main by getting {
            dependsOn(commonMain)
        }

But I'm still getting


The Kotlin source set linux was configured but not added to any Kotlin compilation

[napperley]

The linuxX64 block automatically includes the dependency on the Common module.

[sean]

That's what I was thinking. I'm getting the two errors.

* source set configured but not added
* was expecting native but found common

[napperley]

Is the linuxX64 source set called native?

[napperley]

If that is the case then change linuxX64 { to linuxX64("native").

[sean]

I've been bouncing it around based on different kts samles I've seen.

But initially it was named("linuxX64Main") named("linuxX64"), then the by getting

[sean]

This should be pretty straight forward. I have a single cinterop and no other dependencies. Just trying to output the linux x64 lib

[sean]

Link to t he full gradle file

https://gitlab.com/AnimusDesign/kotlin-logging/blob/dev/linux_x64_native/build.gradle.kts

[napperley]

This block ( https://gitlab.com/AnimusDesign/kotlin-logging/blob/dev/linux_x64_native/build.gradle.kts#L125 ) is redundant since the linuxX64 block automatically includes a dependency on common. Apart from that there doesn't seem to be any other issues with the build file.

[sean]

I did that as a last resort. I have this working in .gradle. But can't get it working in kts.

[napperley]

Have you tried only including the minimum amount of build logic required to publish a library for the linuxX64 target?

[sean]

like just linux x64 target + c interop?

[napperley]

In a new Git branch have a top level build.gradle.kts file that only includes the linuxX64 target, and the required C interop.

[sean]

Just tried commenting out js/jvm target and source set. Wiping local m2 repo, and cleaning. Same error.

Same error source set linux was configured but not added to compilation

[napperley]

Try moving the sourceSets block above the linuxX64 block.

[sean]

source set above linuxX64 target ressult in KotlinSourceSet with name 'linuxX64Main' not found.

[sean]

New KTS, commented to bare linux build

https://gitlab.com/AnimusDesign/kotlin-logging/blob/dev/linux_only/build.gradle.kts#L125

[sean]

It seems to be the cinterop. Knocking back everything to just a base hello world function works and builds

[napperley]

In that case can you gradually add cinterop for each C library, is that possible?

[napperley]

What does ``named("linuxX64Main") {}`` do?

[sean]

I'm trying to add linux support to an existing lib, so I hadn't heard of it before. From the docs it gets a source set, and creates if not present

[sean]

I only have on c lib, and I thought it was a pretty small build. But yeah I need to go through the cinterop docs. I thought I had followed the kts. But it builds and works fine. Like I can do a run application from that same block and it's fine. But it's not getting packaged up into a library

[sean]

Well it is the klib files are in the ~/.m2/repository directory, and matches what's expected. But back to the initial errors I posted

[napperley]

File structure of a Kotlin Native library in the local Maven repository.

[napperley]

Does your published library have a similar structure to the one above? ☝️

[sean]

Thanks again for the help

[sean]

I cast the cinterop to a static lib. That fixed the issue. But now I have a hacky build sh script. I need to look at how to have gradle automatically kick off that static lib building

[napperley]

Did you check the library path (on linux this can be manipulated via the LD_LIBRARY_PATH environment variable) for all dynamic C libraries that are used in the library?

[sean]

Well this isn't a standard library that will be on most systems. I used the LD_PATH for another project. But this includes a small c file that needs to be compiled in conjuction.

I'm working more from a container/backend native lib/app. So those will either need to be via a custom container image or statically included.

[napperley]

Are you referring to Docker for the container part? Have a issue when running a Kotlin Native program via Docker (in Debian) that the C library isn't found/loaded, yet if the program is running via Linux (eg on bare metal through Linux Mint) the C library is found/loaded. Seems that Docker handles C libraries differently compared to how they are handled on Linux.

[sean]

It depends on the which libc is being used. I'm just starting with native. But encountered a similar problem with nodejs target. When trying to compile the js part. The downloaded nodejs could not be launched. I had to build a custom container image to build it.

I will delve into this more once I build tests into my ci/cd pipeline

[sean]

Also while I thought this was related to the static lib. I found out you need to specifiy a nativeMain source set. If being pulled into a multi platform / common project. It worked on another linuxX64 project but not multi platform

val nativeMain by sourceSets.creating {
        dependencies {
            api("org.jetbrains.kotlin:kotlin-stdlib-common")
        }

    }
    val linuxX64 by sourceSets.creating {
        dependsOn(nativeMain)
    }
    targets.withType(KotlinNativeTarget::class.java) {
        compilations["main"].defaultSourceSet.dependsOn(nativeMain)
        when (hostPresetName) {
            "macosX64" -> TODO()
            "linuxX64" -> compilations["main"].defaultSourceSet.dependsOn(linuxX64)
            "mingwX64" -> TODO()
            else -> error("Unsupported host platform")
        }
    }