Joachim Hofer is a long-time senior consultant and lead developer on the Java platform who has recently become a fan of Scala. He regularly contributes to Open Source community projects and shares his experience in his blog and talks. Joachim is a DZone MVB and is not an employee of DZone and has posted 12 posts at DZone. You can read more from them at their website. View Full User Profile

Accessing the Heroku REST API via Dispatch

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Now that I have an extremely simple Heroku app up and running (see my previous post) and don’t know what to do with it, the logical next step for me was to check out Heroku’s REST API. :)

Ok, so first, let’s look up the REST API documentation…

… but wait, such an abstruse beast does not exist! – Instead, we get the Ruby sources of the Heroku REST client. That’s fine with me, except that I don’t speak Ruby so well. But never mind, this looks easy enough.

Let’s check out what to use as REST client API in Scala: Restlet, Jersey or something? – Nooo! Let’s use Dispatch. Dispatch wins the coolness competition hands down, if you ask me. You’ll see below, I hope.

Of course, I’ll use sbt for building my little project. We add the following two dependencies and are done with it:

libraryDependencies ++= Seq(
  "net.databinder" %% "dispatch-http" % "0.8.5",
  "net.databinder" %% "dispatch-lift-json" % "0.8.5")

Now let’s import all the good stuff:

implicit val formats = DefaultFormats

val http = new Http
private val user = "*my-heroku-user*"
private val password = "*my-heroku-password*"

val herokuApi = :/("", 443).as(user, password)
val herokuHeaders = Map(
    "Accept" -> "application/json",
    "X-Heroku-Api-Version" -> "2")

I’m going to prepare a few helpers next, and then we’re ready to rumble:

implicit val formats = DefaultFormats

val http = new Http
private val user = "*my-heroku-user*"
private val password = "*my-heroku-password*"

val herokuApi = :/("", 443).as(user, password)
val herokuHeaders = Map(
    "Accept" -> "application/json",
    "X-Heroku-Api-Version" -> "2")

Next, we can login, for example. This will return our api key, mostly (I don’t know yet what it’s good for though, seeing all the basic authentication that’s going on in the Ruby client).

def login = {
  http(resource(herokuApi / "login")
    < < Map("username" -> user, "password" -> password)
    ># (_.extract[User]) )

def resource(request: Request) = <: < herokuHeaders

(The "< <" and "<: <" above should really be "<<" and "<:<", don't ask me why WordPress puts in a space each time I save this post)

Wait, what's User? I have to define that before the above will work. It's just a simple case class which will be filled by Lift-JSON. And when I'm already at it, I'll define the case class for the next request here, too:

case class User(
    email: String,
    api_key: String,
    verified_at: Option[String])

case class HerokuApp(
    id: Int,
    name: String,
    stack: Option[String],
    requested_stack: Option[String],
    slug_size: Int,
    repo_size: Int,
    dynos: Int,
    workers: Int,
    created_at: String,
    create_status: String,
    repo_migrate_status: String)

Now I can call login and will receive something like this:

This is fun!

Let's use the above HerokuApp case class to request our current Heroku apps:

def apps = http(herokuApi / "apps"
    ># (_.children map (_.extract[HerokuApp])))

Uhm... - yup, that's all there is to it. This returns a convenient list of apps I have running on Heroku:
List(HerokuApp(*my-id*,*my-app-name*,Some(cedar),None,*large-number-1*,*large-number-2*,0,0,2011/10/10 11:52:03 -0700,complete,complete))

This is great, isn't it? - I at least had no idea that it would turn out to be so very easy to connect to Heroku from Scala.

I still don't know what to put up on Heroku, though...



Published at DZone with permission of Joachim Hofer, author and DZone MVB.

(Note: Opinions expressed in this article and its replies are the opinions of their respective authors and not those of DZone, Inc.)



Amara Amjad replied on Sun, 2012/03/25 - 3:03am


please make only Eclipse related stuff available in the PlanetEclipse syndication feed.


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