Test and deploy a Scala application to Heroku

This example demonstrates the integration of GitLab CI/CD with Scala applications using SBT. You can view or fork the example project and view the logs of its past CI jobs.

Add .gitlab-ci.yml file to project

The following .gitlab-ci.yml should be added in the root of your repository to trigger CI: 

image: openjdk:8

stages:
  - test
  - deploy

before_script:
  - apt-get update -y
  - apt-get install apt-transport-https -y
  ## Install SBT
  - echo "deb http://dl.bintray.com/sbt/debian /" | tee -a /etc/apt/sources.list.d/sbt.list
  - apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 642AC823
  - apt-get update -y
  - apt-get install sbt -y
  - sbt sbtVersion

test:
  stage: test
  script:
    - sbt clean coverage test coverageReport

deploy:
  stage: deploy
  script:
    - apt-get update -yq
    - apt-get install rubygems ruby-dev -y
    - gem install dpl
    - dpl --provider=heroku --app=gitlab-play-sample-app --api-key=$HEROKU_API_KEY

In the above configuration:

  • The before_script installs SBT and displays the version that is being used.
  • The test stage executes SBT to compile and test the project.
    • sbt-scoverage is used as an SBT plugin to measure test coverage.
  • The deploy stage automatically deploys the project to Heroku using dpl.

You can use other versions of Scala and SBT by defining them in build.sbt.

Display test coverage in job

Add the Coverage was \[\d+.\d+\%\] regular expression in the Settings ➔ Pipelines ➔ Coverage report project setting to retrieve the test coverage rate from the build trace and have it displayed with your jobs.

Pipelines must be enabled for this option to appear.

Heroku application

A Heroku application is required. You can create one through the Dashboard. Substitute gitlab-play-sample-app in the .gitlab-ci.yml file with your application’s name.

Heroku API key

You can look up your Heroku API key in your account. Add a protected variable with this value in Project ➔ Variables with key HEROKU_API_KEY.