I’ll assume you already know basic knowledge about Ktor and you have built and ran you server locally using Gradle. In this post, the comming text will show you how to run it under Heroku.

Heroku CLI

First of all you need to install Heroku CLI. Please follow the instructions on how to install it at your platform.

Login

heroku login
and fill your login information.

Create

heroku create

Git linking

<APP_NAME> is the name of your app created in the above step.
heroku git:remote -a <APP_NAME>

Gradle Shadow Jar

When your code gets pushed on Heroku, it will goes throgh the building phase, by which you should provie Gradle task name to be executed. We’ll use Shadow plug-in to build and produce an executable jar file to be run at Heroku after the build succeds. So, add the following code to your build.gradle file

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shadowJar {
    baseName = '<Project Name>'
    classifier = null
    version = null
    destinationDir = new File('server') 
}

here, the produced .jar will be created at the server folder.

Now, let’s inform Heroku about our building task

heroku config:set GRADLE_TASK="shadowJar"

Procfile

After build has finished at Heroku, it will execute a command in the file named Procfile that runs your executable code. So,

touch Procfile
and add the following single line in it

web: java -jar server/<Project NAME>.jar

Running locally

In order to verify your app works fine as expected, let’s run your app locall
heroku local web

Your server should be working the same as you were expected and worked with previousely. Try to open it on a browser window to check.

Deploy

After finishing all of the above steps, let’s deploy the project

git push heroku master

… and that’s.

Try checking it at https://<APP_NAME>.heroku.com

Resources

Links helped me a lot understanding how to deploy Ktor on Heroku

Want Kotlin on the Server? Do Ktor

Deploying Kotlin on Heroku with Ktor

Questions?

Please feel free to ask any question or explanation if there are missing content or not clear at some point.