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Deploy Scala applications with SBT

Overview

Clever Cloud allows you to deploy Scala (and Java) applications built with SBT. This document will explain you how to set up your app to run it on our service.

If you’re looking to deploy a Play Framework application, you can have a look at our dedicated deployment guide for play framework applications

Create an application on Clever Cloud

via the web console

  1. Create a new app by clicking on the Add an Application button, in the sidebar.
  2. Select a brand new instance (or a repository from GitHub if your account is linked).
  3. Then select SBT + Scala in the platform list.
  4. Configure your scaling options.
  5. Enter your application’s name and description and click “Next”. You can also select the region you want (North America or Europe).

Refer to https://www.clever-cloud.com/doc/getting-started/ for more details on application creation via the console.

via the Clever Tools CLI

  1. Make sure you have clever-tools installed locally. Report to https://www.clever-cloud.com/doc/reference/clever-tools/getting_started/
  2. In your code folder, do clever create --type <type> <app-name> --region <zone> --org <org> where type is the type of technology you rely on, app-name the name you want for your application, zone deloyment zone (par for Paris and mtl for Montreal), and org the organization ID the application will be created under.

Refer to https://www.clever-cloud.com/doc/reference/clever-tools/create/ for more details on application creation with Clever Tools.

Setting up environment variables on Clever Cloud

With the Clever Cloud console

  1. Go to the Clever Cloud console, and find the app you want to fine tune under it’s organization.
  2. Find the Environment variables menu and select it.
  3. In this menu, you will see a form with VARIABLE_NAME and variable value fields. Fill them with the desired values then select Create.

With the Clever Tools CLI

  1. Make sure you have clever-tools installed locally. Report to https://www.clever-cloud.com/doc/reference/clever-tools/getting_started/
  2. In your code folder, do clever env set <variable-name> <variable-value>

Refer to https://www.clever-cloud.com/doc/reference/reference-environment-variables/ for more details on available environment variables on Clever Cloud. You can of course create custom ones with the interface we just demonstrated, they will be available for your application.

Configure your Scala application

Mandatory configuration

Your application has to listen on port 8080 for worldwide connections (0.0.0.0). We set the system variable http.port to 8080 for you so in many cases (like for play applications) you don’t have anything to do. You need to use the sbt-native-packager in your project.

The sbt-native-packager

We rely on sbt-native-packager to run applications. This plugin provides a stage task which is run during deployment.

If your project doesn’t already use sbt-native-packager, you need to add it to project/plugins.sbt. Please make sure you use an up-to-date version.

In project/plugins.sbt:

addSbtPlugin("com.typesafe.sbt" % "sbt-native-packager" % "1.7.0")

Then you need to configure the package type:

In build.sbt:

enablePlugins(JavaAppPackaging)

# Disable javadoc packaging mappings in (Compile, packageDoc) := Seq()

For more information, please have a look at the documentation for sbt-native-packager

Custom sbt goal

By default, the deployment system runs sbt stage. If you want to run another goal, you can specify it with the SBT_DEPLOY_GOAL environment variable.

Be aware that SBT_DEPLOY_GOAL will infer with CC_SBT_TARGET_DIR.

Multi-module build

If you have a single repository with multiple modules (and no top-level stage task), then you can specify which module to build with SBT_DEPLOY_GOAL.

For instance, if you want to deploy the service1 module, you have to add SBT_DEPLOY_GOAL=service1/stage in the application’s environment variables.

HOCON users

If you’re using HOCON configuration files, then you can have direct acces to environment variables from the configuration file:

application.secret=${APPLICATION_SECRET}

Monitor your application with New Relic

You can use New Relic to monitor your application on Clever Cloud. Please refer to [the New Relic section of the documentation] to configure it for your application.

Environment injection

Clever Cloud injects environment variables from your application settings as mentioned in setting up environment variables and is also injecting in your application production environment, those from your linked add-ons.

To access environment variables from your code, just get them from the environment with System.getenv("MY_VARIABLE"). Be aware that it can return null.

Git Deployment on Clever Cloud

You need git on your computer to deploy via this tool. Here is the official website of Git to get more information: git-scm.com

Setting up your remotes

  1. The “Information” page of your app gives you your git deployment URL. It looks like this: git+ssh://git@push.clever-cloud.com/<your_app_id>.git. Copy it in your clipboard.

  2. Locally, under your code folder, type in git init to set up a new git repository or skip this step if you already have one.

  3. Add the deploy URL with git remote add <name> <your-git-deployment-url>.

  4. Add your files via git add <files path> and commit them via git commit -m <your commit message>.

  5. Now push your application on Clever Cloud with git push <name> master

Refer to https://www.clever-cloud.com/doc/getting-started/quickstart/ for more details on git deployments.

Linking a database or any other add-on to your application

By linking an application to an add-on, the application has the add-on environment variables in its own environment by default.

On add-on creation

Many add-ons do exist on Clever Cloud, please refer to the full list and check add-ons dedicated pages for full instructions.

During add-on creation, you will see Applications screen, with a list of your applications. You can toggle the button to Link and click next. If you finish the process of add-on creation, the application will automatically be linked to it.

Add-on already exists

In the Clever Cloud console, under the Service Dependencies menu of your application, you can use the Link addons dropdown menu to select the name of the add-on you want to link and use the add button to finish the process.

You can also link another application from the same page in the Clever Cloud console, using the Link applications dropdown menu.

More configuration

Need more configuration? To run a script at the end of your deployment? To add your private SSH key to access private dependencies? Go check the Common configuration page.

You may want to have an advanced usage of your application, in which case we recommend you to read the Administrate documentation section.

If you can’t find something or have a specific need like using a non supported version of a particular software, please reach out to the support.