How to create .jar (Create Executable) of the Ktor embedded Server

Question

I'm very new to Kotlin and Ktor and Gradle. Was able to create embedded server as explained in Ktor site, with the following code:

BlogApp.kt:

package blog

import org.jetbrains.ktor.netty.*
import org.jetbrains.ktor.routing.*
import org.jetbrains.ktor.application.*
import org.jetbrains.ktor.features.*
import org.jetbrains.ktor.host.*
import org.jetbrains.ktor.http.*
import org.jetbrains.ktor.response.*

fun Application.module() {
    install(DefaultHeaders)
    install(CallLogging)
    install(Routing) {
        get("/") {
            call.respondText("My Example Blog  sfs 122", ContentType.Text.Html)
        }
    }
}

fun main(args: Array<String>) {
    embeddedServer(Netty, 8080, watchPaths = listOf("BlogAppKt"), module = Application::module).start()
}

and build.gradle:

group 'Example'
version '1.0-SNAPSHOT'

buildscript {
    ext.kotlin_version = '1.1.4-3'

    repositories {
        mavenCentral()
    }
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

apply plugin: 'java'
apply plugin: 'kotlin'

sourceCompatibility = 1.8
ext.ktor_version = '0.4.0'

repositories {
    mavenCentral()
    maven { url  "http://dl.bintray.com/kotlin/ktor" }
    maven { url "https://dl.bintray.com/kotlin/kotlinx" }
}

dependencies {
    compile "org.jetbrains.kotlin:kotlin-stdlib-jre8:$kotlin_version"
    compile "org.jetbrains.ktor:ktor-core:$ktor_version"
    compile "org.jetbrains.ktor:ktor-netty:$ktor_version"
    compile "ch.qos.logback:logback-classic:1.2.1"
    testCompile group: 'junit', name: 'junit', version: '4.12'
}

compileKotlin {
    kotlinOptions.jvmTarget = "1.8"
}
compileTestKotlin {
    kotlinOptions.jvmTarget = "1.8"
}
kotlin {
    experimental {
        coroutines "enable"
    }
}

The server run fine at: localhost:8080

and the I can see the below files in the out folder:

C:\Users\Home\IdeaProjects\Example\out\production\classes\blog

How can I know create an executable file .jar of this server, so I can distribute it to the user?

score 11 · Accepted Answer · edited Sep 23 '17 at 09:22

11

What you need to do is to add the following piece of code to build.gradle file:

jar {
    baseName '<jar_name>'
    manifest {
        attributes 'Main-Class': 'blog.BlogAppKt'
    }

    from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
}

Then run: gradle clean jar. After it's finished navigate to: build/libs and run java -jar <jar_name>.jar.

Or run it using javaw -jar <jar_name>.jar instead of java (you might need to make sure its on the path if the JAVA_HOME is not defined well). This will run it without any console.

P.S. You can also use application plugin or shadowJar.

edited Sep 23 '17 at 09:22

Hasan A Yousef

22,789
24
132
203

answered Sep 22 '17 at 13:20

Opal

81,889
28
189
210

1

When I run it from IJ terminal, I got this error: 'gradle' is not recognized as an internal or external command, operable program or batch file. – Hasan A Yousef Sep 22 '17 at 17:51
1

when I run it from cmd, I got this: * What went wrong: Task 'clean' not found in root project 'blog'. – Hasan A Yousef Sep 22 '17 at 17:53
@HasanAYousef, are you sure you run it from correct location and have java and kotlin plugins applied? – Opal Sep 22 '17 at 18:13
1

Something looks to be wrong in my setup, once I used text editor and command line only, creating the files with `gradle init --type java-library` then creating my files, and compile them `gradle clean jar` everything gone smooth as you described. – Hasan A Yousef Sep 23 '17 at 08:51
@HasanAYousef, no idea what may caused the problem but I'm glad it works now! – Opal Sep 23 '17 at 08:53

score 0 · Answer 2 · answered Jun 24 '23 at 17:02

There is alternative version for build.gradle.kts (kotlin-based gradle file).

tasks.jar {
  // for the case if inside your project there is some duplicate
  duplicatesStrategy = DuplicatesStrategy.EXCLUDE
  manifest.attributes["Main-Class"] = "blog.BlogAppKt"
  configurations["compileClasspath"].forEach { file: File ->
    from(zipTree(file.absoluteFile))
  }
  archiveBaseName.set(project.name + "-all")
}

The result is ./build/libs/${project.name}-all.jar file.

For running:

java -jar ./build/libs/${project.name}-all.jar

How to create .jar (Create Executable) of the Ktor embedded Server

2 Answers2

Linked