development_mode.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE topic SYSTEM "https://resources.jetbrains.com/stardust/html-entities.dtd">

<topic xmlns="" xsi:noNamespaceSchemaLocation="https://resources.jetbrains.com/stardust/topic.v2.xsd"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" id="development_mode" title="Development mode">
    <p>
        Ktor provides a special mode targeted for development. This mode enables the following capabilities:
    </p>
    <list>
        <li><a href="Auto_reload.xml">Auto-reload</a> for reloading application classes
            without restarting the server.
        </li>
        <li>Extended information for debugging <a href="Pipelines.md">pipelines</a> (with stack
            traces).
        </li>
        <li>Extended debugging information on a <a href="status_pages.md">response page</a> in
            a case of a <emphasis>5**</emphasis> server error.
        </li>
    </list>
    <note>
        <p>
            Note that development mode affects performance and shouldn't be used in production.
        </p>
    </note>

    <chapter title="Enable development mode" id="enable">
        <p>
            You can enable development mode in different ways: in the application configuration file,
            using a dedicated system property or environment variable.
        </p>


        <chapter title="application.conf" id="application-conf">
            <p>
                To enable development mode in the
                <a href="Configurations.xml" anchor="hocon-file">application.conf</a> file,
                set the <code>development</code> option to <code>true</code>:
            </p>
            <code style="block">
                ktor {
                    development = true
                }
            </code>
        </chapter>


        <chapter title="The 'io.ktor.development' system property" id="system-property">
            <p>
                The <control>io.ktor.development</control> <a href="https://docs.oracle.com/javase/tutorial/essential/environment/sysprop.html">system property</a>
                allows you to enable development mode when running your application:
            </p>
            <list>
                <li>
                    <p>
                        To run an application in development mode using IntelliJ IDEA,
                        pass <code>io.ktor.development</code> with the <code>-D</code> flag to
                        <a href="https://www.jetbrains.com/help/idea/run-debug-configuration-kotlin.html#1">VM options</a>:
                    </p>
                    <code style="block">
                        -Dio.ktor.development=true
                    </code>
                </li>
                <li>
                    <p>
                        If you run your application using a <a href="server-dependencies.xml">Gradle</a> task, you can pass
                        <code>io.ktor.development</code> to the
                        <code>applicationDefaultJvmArgs</code> property in a <path>build.gradle(.kts)</path> file:
                    </p>
                    <tabs group="languages">
                        <tab title="Gradle (Kotlin)" group-key="kotlin">
                            <code style="block" lang="Kotlin">
                                application {
                                    applicationDefaultJvmArgs = listOf("-Dio.ktor.development=true")
                                }
                            </code>
                        </tab>
                        <tab title="Gradle (Groovy)" group-key="groovy">
                            <code style="block" lang="Groovy">
                                application {
                                    applicationDefaultJvmArgs = ["-Dio.ktor.development=true"]
                                }
                            </code>
                        </tab>
                    </tabs>
                </li>
            </list>
            <tip>
                <p>
                    You can also use the <code>-ea</code> flag to enable development mode.
                    Note that the <code>io.ktor.development</code> system property passed with the <code>-D</code> flag
                    takes precedence over <code>-ea</code>.
                </p>
            </tip>
        </chapter>


        <chapter title="The 'io.ktor.development' environment variable" id="environment-variable">
            <p>
                To enable development mode for a <a href="http-client_engines.md" anchor="native">Native client</a>,
                use the <code>io.ktor.development</code> environment variable.
            </p>
        </chapter>
    </chapter>

</topic>