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Vaadin-on-Kotlin Vaadin 14 Example App / Archetype

Template for a simple Vaadin-on-Kotlin Vaadin 14-based application that only requires a Servlet 3.0 container to run. Just clone this repo and start building your awesome app!

You'll start with this app when you follow the Getting Started tutorial.

Preparing Environment

The Vaadin 14 build requires node.js and npm. You can either use the Vaadin Gradle plugin to install it for you (the vaadinPrepareNode task, handy for the CI), or you can install it to your OS:

To make Vaadin Gradle plugin install node.js+npm for you, just run the following command in the project's sources (you only need to run this command once):

./gradlew vaadinPrepareNode

Also make sure that you have Java 8 (or higher) JDK installed.

Getting Started

To quickly start the app, just type this into your terminal:

git clone
cd vok-helloworld-app-v10
./gradlew build web:appRun

Gradle will automatically download an embedded servlet container (Jetty) and will run your app in it. Your app will be running on http://localhost:8080.

Since the build system is a Gradle file written in Kotlin, we suggest you use Intellij IDEA to edit the project files. The Community edition is enough to run the server via Gretty's ./gradlew appRun. The Ultimate edition will allow you to run the project in Tomcat - this is the recommended option for a real development.

The 'complete' sources

You can switch the git branch from 'master' to 'complete', to see the outcome application of the Vaadin-on-Kotlin Getting Started tutorial.

Supported Modes

Runs in Vaadin 14 npm mode, using the Vaadin Gradle Plugin.

Both the development and production modes are supported. To prepare for development mode, just run:

./gradlew clean vaadinPrepareFrontend

If you don't have node installed, you can use Vaadin plugin to download node.js for you:

./gradlew vaadinPrepareNode

To build in production mode, just run:

./gradlew clean build -Pvaadin.productionMode

If you don't have node installed in your CI environment, you can use Vaadin plugin to download node.js for you beforehand:

./gradlew clean vaadinPrepareNode build -Pvaadin.productionMode


To compile the entire project in production mode, run ./gradlew -Pvaadin.productionMode.

To run the application in development mode, run ./gradlew appRun and open http://localhost:8080/.

To produce a deployable production-mode WAR:

  • run ./gradlew -Pvaadin.productionMode
  • You will find the WAR file in build/libs/*.war
  • To revert your environment back to development mode, just run ./gradlew or ./gradlew vaadinPrepareFrontend (omit the -Pvaadin.productionMode) switch.

This will allow you to quickly start the example app and allow you to do some basic modifications.

Dissection of project files

Let's look at all files that this project is composed of, and what are the points where you'll add functionality:

Files Meaning
build.gradle.kts, settings.gradle.kts Gradle build tool configuration files. Gradle is used to compile your app, download all dependency jars and build a war file
gradlew, gradlew.bat, gradle/ Gradle runtime files, so that you can build your app from command-line simply by running ./gradlew, without having to download and install Gradle distribution yourself.
.travis.yml Configuration file for Travis-CI which tells Travis how to build the app. Travis watches your repo; it automatically builds your app and runs all the tests after every commit.
.gitignore Tells Git to ignore files that can be produced from your app's sources - be it files produced by Gradle, Intellij project files etc.
web/ The web Gradle module which will host the web application itself. You can add more Gradle modules as your project will grow. Visit the web module docs for more documentation.

Development with Intellij IDEA Ultimate

The easiest way (and the recommended way) to develop Karibu-DSL-based web applications is to use Intellij IDEA Ultimate. It includes support for launching your project in any servlet container (Tomcat is recommended) and allows you to debug the code, modify the code and hot-redeploy the code into the running Tomcat instance, without having to restart Tomcat.

  1. First, download Tomcat and register it into your IntelliJ IDEA properly:
  2. Then just open this project in Intellij, simply by selecting File / Open... and click on the build.gradle file. When asked, select "Open as Project".
  3. You can then create a launch configuration which will launch the web module as exploded in Tomcat with Intellij: just scroll to the end of this tutorial:
  4. Start your newly created launch configuration in Debug mode. This way, you can modify the code and press Ctrl+F9 to hot-redeploy the code. This only redeploys java code though, to redeploy resources just press Ctrl+F10 and select "Update classes and resources"


A very simple Vaadin-on-Kotlin Vaadin 10 HelloWorld app which you start off when building your own apps





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