Development mode

Ktor provides a special mode targeted for development. This mode enables the following capabilities:

Auto-reload for reloading application classes without restarting the server.
Extended information for debugging pipelines (with stack traces).
Extended debugging information on a response page in a case of a 5** server error.

Enable development mode

You can enable development mode in different ways: in the application configuration file, using a dedicated system property, or environment variable.

To enable development mode in a configuration file, set the development option to true:

                        ktor {
                            development = true
                        }
                    

                        ktor:
                            development: true
                    

The io.ktor.development system property allows you to enable development mode when running your application:

To run an application in development mode using IntelliJ IDEA, pass io.ktor.development with the -D flag to VM options:
-Dio.ktor.development=true
If you run your application using a Gradle task, you can pass io.ktor.development to the applicationDefaultJvmArgs property in a build.gradle(.kts) file:
application { applicationDefaultJvmArgs = listOf("-Dio.ktor.development=true") }
application { applicationDefaultJvmArgs = ["-Dio.ktor.development=true"] }

To enable development mode for a Native client, use the io.ktor.development environment variable.

Last modified: 02 April 2024