FlashDrive automatically builds your Java app from your code.
In order to do that FlashDrive uses buildpacks to detect and build automatically your app.

The Java buildpack offers several ways to build your code from source or from a compiled artifact.

Create your app on FlashDrive

Create a new app and link it with your repository using SSH keys.

Read this article for a detailed procedure or check this video :

Specify a Java Version

You can specify a Java version by adding a file called to your repository.

Set a property java.runtime.version in the file:


Supported versions

  • Java 7 – 1.7.0_302
  • Java 8 – 1.8.0_292
  • Java 11 – 11.0.11
  • Java 13 – 13.0.7
  • Java 15 – 15.0.3
  • Java 16 – 16.0.1

While minor version are provided we recommend you to always uses the major version (like 11) instead of a specific minor version to ensure your app stays updated automatically by the builder in case of security or critical updates.


The Procfile informs the engine of the type of app you are running (web or worker) and prepares the infrastructure accordingly. Make sure to use the same server type as during the app creation (web or worker) or you will need to manually alter the network settings of the app.

web: java -jar target/myapp.jar


This file is used by Maven, the dependency manager of Java. It’s required for the app to build.

You can create this file by running locally mvn archetype:create

This file indicates the version of Java (and Maven, see below Maven version) you want to use. By default, FlashDrive uses JDK8, and we recommend using this version when possible, but you can specify one of these versions : 1.7 (Java 7), 1.8 (default version, JDK8), 11, 13, 15 and 16

The file would look like this :


If you want to use the default version this file is not required.

Using the Zulu JDK

In addition to the standard JDK you can run the Azul Zulu JDK with FlashDrive Java apps. Zulu is an Open Source certified build of OpenJDK and 100% compliant with Java OpenSE standards.

To use Zulu JDK write your file like this :


Maven Version can also be used to specify the Maven version to run :


Accepted versions of maven are :

  • 3.2.5
  • 3.3.9
  • 3.5.4
  • 3.6.2
  • The default version is 3.6.2

Support for Springboot and Thorntail

The Java buildpack automatically detects Springboot and Thorntail frameworks and creates the appropriate commands.

For Springboot :

java -Dserver.port=$PORT $JAVA_OPTS -jar target/*.jar

For Thorntail :

java -Dswarm.http.port=$PORT $JAVA_OPTS -jar target/*.jar

If a Procfile is present those commands will be ignored.

Using a custom Maven Settings file

A settings.xml file determines the Maven configuration. Read more on this page.

When a file settings.xml is present inside the root directory of your code, FlashDrive will use it to configure Maven.

Alternatively, the emplacement of the settings.xml file can be set as an environment variable (before build) with the key MAVEN_SETTINGS_PATH (local file) or MAVEN_SETTINGS_URL (hosted on a URL)

Using passport protected repositories

You can use any environment variable of your app (to be set before the app build is required) to use inside the settings.xml file : ${env.ENV_VAR} where ENV_VAR is the name of your variable. Never store passwords inside your code repository but uses the environment variables to do that.

Here’s an example with settings.xml file using a private repository like Jfrog Artifactory hosted version :


Create persistent storage

One of the major improvements of FlashDrive in comparison to others app hosting solutions is the ability to create Virtual Disks available for any copy of your app inside the same stack.

Virtual disks allow you to store data safely and securely, without the need to use an additional S3 bucket, and every app size gets free disk space depending on its size (see our pricing for more information).

In addition to that, Virtual disks are backup every day with 10 days history and ransomware protection at no additional cost.

Read this article for more informations about virtual disks and how to add one to your app.

Add a domain name

Please check this article for a detailled method on how to use your domain name with FlashDrive apps.

Define environment variables

Note: Environment variables set in your app settings are injected during the build process. If the build of your app needs to use an env variable make sure to set it before requesting the build.

FlashDrive lets you externalize the configuration of your app : the FlashDrive cluster will automatically injects the data when the app start or restart.

Environement variables can includes any external data your app needs to run like external ressources, databases addresses, encryption keys etc…

To add an environment variable, access your app settings and click “Add ENV Variable” :

Enter the key (like DATABASE_USER) and the value and click “Add”. FlashDrive will automatically add your environment variable and restart your app after a one minute delay (to let you add more env variables if necessary without restarting the app each time a new variable is added).

Provision a database

FlashDrive Marketplace includes all popular datastore engines including Mysql, Postgres, MongoDB and Redis.
To add a database to your app, click on Marketplace and select the database you want to run, then create the new app database inside the same stack as your Python app.

Once the app is running, visit the database app’s settings and retreive the “internal name” :

Use this internal name as you would use a server address, for instance for mysql this name replace the usual “localhost”. Some scripts requires you to add the database port at the end of the server address. FlashDrive uses common port for each database software, for MySQL it will be 3306 and you can write it like that inside your scripts : internal-name:3306
Postgres usually uses credentials sent inside the login URL, like that : postgres://<user>:<password>@<internalname>:5432/<database>

The login and password information is available inside the Environment Variables of the database app.

Reach your app from another app

Inside your app stack, you can reach any other FlashDrive app member of this stack on any port. FlashDrive automatically routes the traffic internally and open the appropriate port. By opposition, your app is only reachable on ports 80/443 from outside of FlashDrive.

To reach your app internally, retrieve the internal name from your app settings page :

This name can be used to reach your app from another app inside the same stack. Use it in any form that works with your script :


Note : https:// is not available, all the traffic inside apps is already encrypted by the cluster.


FlashDrive uses at rest encryption for the app virtual disks, build images, and encrypted transport from inside the cluster. To make sure the traffic is encrypted between your app and the browser of your users you can set up SSL certificates for any domain name connected to the app (including the FlashDrive’s default domain name).

Scale your App

From your app settings you can scale your app vertically and horizontally : by upgrading the app size (refer to our pricing for app sizes details) or by adding more nodes.

Additional nodes will run another copy of your app inside another FlashDrive server located inside the same cluster (same geographical location). Traffic is automatically sent to the least occupied node by FlashDrive’s load balancer.

Note: Apps that uses Virtual Disks will share the same file structure and read/write on the same disk. It’s fine in most cases for intensive read activity but can create bottlenecks and corrupted data if several nodes of the same app write on the same file at the same time. If your apps use intensive reads on virtual disks consider upgrading the app size instead of adding more nodes.

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