Creating a server
Before creating a Ktor application, you need to take into account how your application will be deployed:
In this case, an application engine used to process network requests should be a part of your application. Your application has control over engine settings, connection, and SSL options.
As a servlet
In this case, a Ktor application can be deployed inside a servlet container (such as Tomcat or Jetty), which controls the application lifecycle and connection settings.
To deliver a Ktor server application as a self-contained package, you need to create a server first. Server configuration can include different settings: a server engine (such as Netty, Jetty, etc.), various engine-specific options, host and port values, and so on. There are two main approaches in Ktor for creating and running a server:
embeddedServerfunction is a simple way to configure server parameters in code and quickly run an application.
EngineMainprovides more flexibility to configure a server. You can specify server parameters in a file and change a configuration without recompiling your application. Moreover, you can run your application from a command line and override the required server parameters by passing corresponding command-line arguments.
Configuration in code
embeddedServer function is a simple way to configure server parameters in code and quickly run an application. In the code snippet below, it accepts an engine and port as parameters to start a server. In the example below, we run a server with the
Netty engine and listen on the
You can find the full example here: embedded-server.
Configuration in a file
EngineMain starts a server with the selected engine and loads the application modules specified in the external configuration file placed in the resources directory: application.conf or application.yaml. Besides modules to load, a configuration file can include various server parameters (the
8080 port in the example below).
You can find the full examples here: engine-main and engine-main-yaml.
A Ktor application can be run and deployed inside servlet containers that include Tomcat and Jetty. To deploy inside a servlet container, you need to generate a WAR archive and then deploy it to a server or a cloud service that supports WARs.