How to deploy my spray API into production?

Question

I'm thinking about how should be the process to deploy my already locally tested rest api to the cloud, lets say an infrastructure as a service (not a platform as a service such as Heroku) like amazon.

I have my local envorinment set up with sbt up and running but my question is How should I deploy this in a production environment?

Is it sane to define a process in which the devops pulls the most recent changes from the git repo and then simply executes sbt run?

I want to know how does the teams that uses scala+spray+sbt deploys their apis to a production environment.

Answer 1

You should build a jar with the plugin sbt-assembly

addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.9.0")

Then you can run the jar in production with java -jar

If you give version number to your project, this is a rather classic process.

Hope it helps.

Answer 2

Never went to PRO with spray-akka. Only pet projects. My suggestions here should be taken as inspiration. I know some of the options I present are costly in terms of maintenance or prone to errors.

Packaging

I only used maven-shade-plugin (no experience with sbt) but I guess there's a similar solution.

Packaging Issues

There's few issues with this approach though. Akka and many of the spray modules use the references.conf and application.conf convention. When assembly/shading all your dependencies the resources (since they are named the same) may overwrite and you'd be unable to start the application.

The quick and dirty solution I found was to copy/paste the application and ref.conf of the dependencies into one controlled by me.

Answer 3

The heart of our services is scala + akka + spray + mongo. So we are using GitHub for version control. After merging checked PRs to the master branch, Jenkins automaticaly tests'n'builds project. If all tests were successful then Jenking runs a couple of scripts:

1. Increment project version (currently written in shell, but will be changed to sbt)
2. Run assembly task with sbt-assembly
3. Run deploy script (written in Python with Fabric) wich deploys our jar to EC2

Basicaly on the thrid step you have a couple of choices:

Make a runnable jar using IO/Spray boot file:

object Boot extends App {
  implicit val system = ActorSystem("ServiceName")
  val log = system.log
  val service = system.actorOf(Props[Service], name="serviceActor")
  IO(Http) ! Http.Bind(service, interface = host, port = port)
}

Make a runnable jar as Akka's microkernel:

In this case you should extend Bootable trait and override startup and shutdown methods:

class Kernel extends Bootable {
  // many lines of code
  def startup() {
    scheduler.start()
    SomeActorSystem.startup()
  }

  def shutdown() {
    scheduler.shutdown()
    SomeActorSystem.shutdown()
    system.shutdown()
  }
}

Using a TypeSafe startscript:

Can't show an example, but it has a good intro on github =)

We are using all of this way in different cases.