In this Heroku tutorial, I’d like to share my experience about how to deploy a Java application on to Heroku cloud platform by putting a JAR file to Heroku, using Maven and Heroku CLI.

Why deploying JAR file?

Heroku provides several ways for deploying a Java application, so when using JAR deployment option?

Consider using JAR deployment if you’re in one of the following scenarios:

• You don’t want to put your code (for security reason) to Heroku via Git push deployment
• You have only JAR file, without source code
• Your project compilation time exceeds the Heroku’s limit, so you have to compile and package your project locally

In this tutorial, I suppose that you already have a Java project, a Heroku account, and Heroku CLI and Maven installed on your computer.

Steps for deploying JAR file:

• Use Maven to build and package your Java project to an executable JAR file
• Install Heroku Java CLI plugin
• Create a new Heroku app
• Deploy the JAR file

Now, let me walk you through each step in details.

 

1. Package JAR file using Maven

Be sure that you declare the packaging type of your project in pom.xml file is jar:

<project ...>

...   

<packaging>jar</packaging>

...

</project>

You can build and package your project to an executable JAR file in command prompt (terminal) by typing the following command (be sure that the current directory is your project’s root):

mvn package

In case you use Eclipse IDE, right-click on project and select Run As > Maven goal… and specify the goal package. The result is a JAR file created under target folder of the project.

2. Install Java Plugin for Heroku CLI

Next, type heroku login to sign in your Heroku account in Heroku CLI. Then type the following command to install the Java Plugin for Heroku CLI:

heroku plugins:install java

You would see the output as follows:

3. Deploy JAR File to Heroku

Next, create a new app on Heroku by executing this command:

heroku create app_name --no-remote

The option --no-remote tells Heroku do not set Git remote reference for the project, as you’re going to deploy your app by sending JAR file, not by sending source code via Git push.

heroku deploy:jar target/your_app.jar -a app_name

You would see the output looks something like this:

That’s it. You’re all set. Your application has been successfully deployed on to Heroku using JAR deployment. Now you can access your application via URL https://app_name.herokuapp.com.

To watch the steps of deploying a JAR file to Heroku step by step, I recommend you watch the following video:

 

Other Heroku tutorials:

• What is Heroku for Developers (Benefits, how it works and key concepts)
• Deploy Simple Spring Boot Project to Heroku using Git and Heroku CLI
• Change Java version for Apps deployed on Heroku
• Add Custom Domain Names for Heroku Apps
• Deploy Spring Boot App with MySQL Database on Heroku
• How to Enable Secure Connection for Heroku Apps