Monthly Archive for: ‘November, 2014’

Deploy Multi-Language Projects to Heroku


In my current technology playground chatty I use Java, TypeScript and JavaScript as programming languages. For the TypeScript/HTML based Web UI I use a node/grunt based build, for the Java parts I use Gradle. Heroku is a great cloud platform, deploying software is done using a git push. Using the predefined build-packs, it is pretty easy to deploy Java OR Node based applications, but how to deploy a multi-language project that uses both?

Here the heroku-buildpack-multi helps a lot. Simply invoke

$ heroku config:add BUILDPACK_URL=

and add all buildpacks to a top-level .buildpack file, that’s it. Then, each build is done sequentially as specified in the .buildpack file. The .buildpack for chatty looks like

Another important thing to know about these buildpacks assume that the corresponding project is located at top-level. So the node build expects a package.json in the root directory. Since chatty is a multi-project build, the web part is located in subprojects/com.toedter.chatty.client.web. For me, the easiest solution was to copy the package json to the root directory, and the provide a grunt file, that copies all node_modules to the subproject. Additionally I use the grunt contribution grunt-hub to invoke the gruntfile located in the subproject with target distBoot (to provide a distribution of the JacaScript/HTML/CSS/libs that can be deployed together with the Spring Boot based server part. The last thing is to define a grunt task named ‘heroku’ that is invoked by the buildpack. The whole top-level grunt file looks like:

module.exports = function (grunt) {
    'use strict';

        hub: {
            all: {
                src: ['subprojects/com.toedter.chatty.client.web/Gruntfile.js'],
                tasks: ['distBoot']
        copy: {
            node_modules: {
                expand: true,
                src: 'node_modules/**/*',
                dest: 'subprojects/com.toedter.chatty.client.web/'


    grunt.registerTask('heroku', ['copy:node_modules', 'hub']);

The Java part is pretty straight forward since gradle is the master build system of chatty. The only subproject I want to deploy to heroku is the Spring Boot based server, located in subprojects/com.toedter.chatty.server.boot. In the file I just added a new gradle task ‘stage’:

task stage(dependsOn: ['jar', 'bootRepackage'])

that creates the fat jar for the chatty spring boot application. The resulting web application demo is then deployed to Heroku, you can check it out at

Regarding IDE integration there are Heroku plugins for IntelliJ IDEA and Eclipse. In the next blog of this series, I will explain how to use Travis-CI for a continuous delivery, including the automatic deployment to Heroku after a successful build.