Add Play/Scala CI example with deployment to Heroku

doc/ci/examples/README.md

@@ -9,6 +9,7 @@ Apart from those, here is an collection of tutorials and guides on setting up yo
 - [Testing a PHP application](php.md)
 - [Test and deploy a Ruby application to Heroku](test-and-deploy-ruby-application-to-heroku.md)
 - [Test and deploy a Python application to Heroku](test-and-deploy-python-application-to-heroku.md)
+- [Test and deploy a Scala/Play application to Heroku](test-and-deploy-scala-play-application-to-heroku.md)
 - [Test a Clojure application](test-clojure-application.md)
 - [Test a Scala application](test-scala-application.md)
 - [Test a Phoenix application](test-phoenix-application.md)

doc/ci/examples/test-and-deploy-scala-play-application-to-heroku.md

+## Test and Deploy a Scala/Play application
+This example guides you in setting up Gitlab CI for Play Scala web applications with automated testing and deployment to Heroku. It is accompanied with a [running example](https://gitlab-play-sample-app.herokuapp.com/) ([source](https://gitlab.com/jasperdenkers/play-scala-heroku-sample-app) and [build status](https://gitlab.com/jasperdenkers/play-scala-heroku-sample-app/builds)).
+
+### Configure CI for your project
+Add the following `.gitlab-ci.yml` to an existing project based on Play:
+
+```yaml
+image: java:8
+
+before_script:
+  # 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 -yq
+  - apt-get install sbt -y
+  - sbt sbt-version
+
+stages:
+  - test
+  - deploy
+
+test:
+  stage: test
+  script:
+    - sbt test
+
+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
+```
+
+It consists of two stages:
+1. `test` - executes tests using SBT.
+2. `deploy` - automatically deploys the project to Heroku using dpl.
+
+### Heroku application
+A Heroku application is required. You can create one through the [Dashboard](https://dashboard.heroku.com/). 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](https://dashboard.heroku.com/account). Add a variable with this value in `Project > Variables` with key `HEROKU_API_KEY`.