Full Stack Scala on Heroku

This is an example of a full stack Scala application deployed on Heroku. See this blog post.

Stack

The backend uses the Play framework, together with Slick to access a postgres database.

The frontend uses the Laminar framework for UI rendering.

Deploy

The app is hosted on Heroku. In order to deploy,

# Login to Heroku
heroku login

# Make sure to use the same name as in project/BackendSettings.scala
heroku apps:create full-stack-scala-example --region eu
heroku addons:create heroku-postgresql:hobby-dev

# Create a secret for the Play application
heroku config:set APPLICATION_SECRET=mycoolsecret

# Optional
export SBT_OPTS="-Xmx6G -XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -XX:MaxPermSize=6G -Xss2M  -Duser.timezone=GMT"

sbt clean stage backend/deployHeroku

To see the files on the deployed server:

heroku run bash --app APPNAME

Dev environment

In order to run the app locally, you will need to set up a postgres database at localhost:5432 for Slick to connect to.

export JDBC_DATABASE_URL = "jdbc:postgresql://localhost:5432/<db_name>?user=<your_user>&password=<your_password>"

(5432 being the port by default for postgres databases.)

Then, you can use, in one command line (terminal)

# Frontend hot reload only on localhost:8080
sbt dev

and in another,

# Backend hot reload only on localhost:9000
sbt backend/run