Ktor applications can be self-hosted or hosted on an Application Server. This section shows you how to host Ktor applications externally.

Table of contents:

• Running an application in an external host
  • Defining the configuration
  • Deploying the hosted application
• Running the application from inside the IDE
  • IntelliJ IDEA
• Use automatic reloading

Running an application in an external host

When you need to run a Ktor application in an independently maintained host (for instance Tomcat), you will need an application.conf file to tell Ktor how to start your application.

Defining the configuration

In the resources folder, create a file named application.conf with the following contents

ktor {
    deployment {
        port = 8080
    }

    application {
        modules = [ my.company.MyApplication.ApplicationKt.main ]
    }
}

Replace my.company.MyApplication with your application’s package, and ApplicationKt with the name of the file your Application.main function is contained in.

Deploying the hosted application

// TODO

Running the application from inside the IDE

Running applications in a development environment such as IntelliJ IDEA, is supported by using development engines.

IntelliJ IDEA

1. Create a new Run Configuration using “Application” as a template
2. For the main class use one of the following engines
   • Netty: use io.ktor.server.netty.EngineMain
   • Jetty: use io.ktor.server.jetty.EngineMain
3. Specify the Module to be used
4. Save the Configuration by giving it a name

Once the configuration is saved, you can now run your application for development/debug purposes from inside IntelliJ IDEA, without having to deploy to a container or setup any application servers.

See also: Configuration

Use automatic reloading

Ktor can automatically reload the application when changes to the class files are detected, i.e. when you build the Application. Enable this feature by adding watch configuration to application.conf:

ktor {
    deployment {
        port = 8080
        watch = [ my.company ]
    }

    …
}

Check Automatic Reloading article for more details.