Setting up Scala, SBT, Play, Akka

Part 1 : Setting up Scala, SBT, Play, Akka

This will be multi-part series in building a cloud API server for our PaaS with cloud instrumentation using a messaging layer.

1. Let us setup SBT 0.13.

Installing in debian

echo "deb https://dl.bintray.com/sbt/debian /" | sudo tee -a /etc/apt/sources.list.d/sbt.list
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 642AC823
sudo apt-get update
sudo apt-get install sbt

(or)

Manual install of sbt

• Download the sbt_launch.jar to your ~/bin directory.

• Create a script named sbt in your ~/bin directory with the following contents.

  java -server -Xms1024M -Xmx3072M -Xss32M -XX:+CMSClassUnloadingEnabled -XX:MaxPermSize=1024M -XX:+UseG1GC -XX:+AggressiveOpts -XX:SurvivorRatio=128 -XX:MaxTenuringThreshold=0 -jar dirname $0/sbt-launch.jar “$@”

• Adjust the -Xmx, -Xms -XX:MaxPermSize based on the RAM you have.

At Megam we all have atleast 8GB or > of RAM.

*optional Install sbt-eclipse

Install the scala-ide eclipse plugin for Eclipse Mars.

Help > Install New Software >

Add the correct link from herehttps://scala-ide.org/download/nightly.html

You can install typesafe stack and download templates from here. https://typesafe.com/stack/download#template https://typesafe.com/resources/typesafe-stack/downloading-installing.html

• Create a new project in eclipse. Scala – Worksheet allows you to play around with REPL inside eclipse editor. or use command line, to use REPL

sbt console

If you only plan to use scala, you are done here. You can tweak your Build.scala to use the scala version you want.

2. Eclipsify scala project

https://github.com/typesafehub/sbteclipse/wiki https://github.com/typesafehub/sbteclipse Create a file .sbt/plugins/plugins.sbt and add the following to include eclipse plugin support.

addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "2.3.0"

If you created a project from command line then run sbt > eclipse to eclipsify a project..

ram@rammegam:~/code/megam/workspace/nilam$ sbt
[info] Loading project definition from /home/ram/code/megam/workspace/nilam/project
[info] Set current project to nilam (in build     file:/home/ram/code/megam/workspace/nilam/)
[nilam] $ eclipse
[info] About to create Eclipse project files for your project(s).
[info] Updating {file:/home/ram/code/megam/workspace/nilam/}nilam...
[info] Resolving org.hibernate.javax.persistence#hibernate-jpa-2.0-api;1.0.1.Fin                                                                                [info] Done updating.
[info] Compiling 6 Scala sources and 1 Java source to /home/ram/code/megam/workspace/nilam/target/scala-2.9.1/classes...
[info] Successfully created Eclipse project files for project(s):
[info] nilam

3. If you with to use akka

A sample akka source code for the Typesafe Stack (https://typesafe.com/stack). https://typesafe.com/resources/tutorials/getting-started-with-akka-scala.html From your akka code type sbt run:

ram@rammegam:~/code/megam/workspace/megam_akka$ sbt run
[info] Loading project definition from /home/ram/code/megam/workspace/megam_akka/project
[info] Set current project to nilam (in build     file:/home/ram/code/megam/workspace/megam_akka/)
[info] Updating {file:/home/ram/code/megam/workspace/megam_akka/}nilam...
[info] Resolving com.typesafe#config;0.3.1 ...
[info] downloading https://repo.typesafe.com/typesafe/releases/com/typesafe/akka/akka-actor/2.0.3/akka-actor-2.0.3.jar ...
[info]     [SUCCESSFUL ] com.typesafe.akka#akka-actor;2.0.3!akka-actor.jar (9117ms)
[info] downloading https://repo.typesafe.com/typesafe/releases/com/typesafe/config/0.3.1/config-0.3.1.jar ...
[info]     [SUCCESSFUL ] com.typesafe#config;0.3.1!config.jar(bundle) (3345ms)
[info] Done updating.
[info] Compiling 1 Scala source to /home/ram/code/megam/workspace/megam_akka/target/scala-2.9.2/classes...
[info] Running org.megam.akka.Nilam
Count is 3
[success] Total time: 25 s, completed 6 Nov, 2012 12:31:57 PM

4. Setting up Play framework

Let us create a project titled megam_play which will use external dependencies like scaliak, newman, scalaz This project megam_play was created by cloning an existing typesafe_stack (play scala sample template). You are free to pick any other template from Github.com Adding library dependencies in your Build.scala file. The scaliak, amqp dependency has been moved to a common artifact named “megam_common”

import sbt._
import play.Project._

object ApplicationBuild extends Build {

 val appName = "megam_play"

  val appVersion = "0.1.0"

  val organization = "Megam Systems"

  val homepage = Some(url("https://www.megam.co"))

  val startYear = Some(2013)

  val description = "RESTful API server for the megam platform. Uses Riak and Memcache"

  /**
   *   if you use groupID %% artifactID % revision instead of groupID % artifactID % revision
   *   (the difference is the double %% after the groupID), sbt will add your project’s Scala version
   *   to the artifact name.
   */

  val play2AuthVersion = "0.11.0-SNAPSHOT"
  val megamVersion = "0.1.0-SNAPSHOT"

  val appDependencies = Seq(
    javaCore, cache,javaEbean,
    "com.twitter.service" % "snowflake" % "1.0.2" from "https://s3-ap-southeast-1.amazonaws.com/megampub/0.1/jars/snowflake.jar", //don't move this below.
"com.github.indykish" % "megam_common_2.10" % megamVersion excludeAll (
  ExclusionRule("commons-logging","commons-logging"),
  ExclusionRule("org.slf4j","slf4j-jdk14")),
"com.github.mumoshu" %% "play2-memcached" % "0.3.0.2",
"jp.t2v" %% "play2-auth" % play2AuthVersion,
"jp.t2v" %% "play2-auth-test" % play2AuthVersion % "test",
"com.stackmob" %% "newman" % "1.3.0" % "test")

  val main = play.Project(appName, appVersion, appDependencies).settings(
sbt.Keys.resolvers += "Sonatype Snapshots" at "https://oss.sonatype.org/content/repositories/snapshots",
sbt.Keys.resolvers += "Typesafe Snapshots" at "https://repo.typesafe.com/typesafe/snapshots/",
sbt.Keys.resolvers += "Scala-Tools Maven2 Snapshots Repository" at "https://scala-tools.org/repo-snapshots",
sbt.Keys.resolvers += "Twitter Repo" at "https://maven.twttr.com", // finagle
sbt.Keys.resolvers += "spray repo" at "https://repo.spray.io", //spray client used in newman.
sbt.Keys.resolvers += "spray nightly" at "https://nightlies.spray.io", //spray client nighly used in newman (0.23.0).
sbt.Keys.resolvers += "Spy Repository" at "https://files.couchbase.com/maven2" // required to resolve `spymemcached`, the plugin's dependency.
)

}

We package debs, hence build.sbt contains the required statements

import sbt
import Process._
import com.typesafe.sbt.packager.debian.Keys._
import    com.typesafe.sbt.packager.linux.LinuxPackageMapping
import S3._

scalaVersion := "2.10.3"

scalacOptions := Seq(
  "-unchecked",
  "-deprecation",
  "-feature",
  "-optimise",
"-Xcheckinit",
"-Xlint",
"-Xverify",
"-Yinline-warnings",
"-Yclosure-elim",
"-language:postfixOps",
"-language:implicitConversions",
"-Ydead-code")

com.typesafe.sbt.packager.debian.Keys.name in Debian := "megamplay"

maintainer in Debian:= "Rajthilak <rajthilak@megam.co.in>"

packageSummary := "Cloud API server - Megam."

packageDescription in Debian:= " (REST based) Cloud API server for Megam platform.The API server protects the resources using HMAC based authorization, as provided to a customer during onboarding."

s3Settings

linuxPackageMappings in Debian <+= (baseDirectory) map { bd =>
  (packageMapping((bd / "bin/mp") -> "/usr/local/share/megamplay/bin/mp")
   withUser "root" withGroup "root" withPerms "0755")
}

linuxPackageMappings <+= (baseDirectory) map { bd =>
  val src = bd / "target/staged"
 val dest = "/usr/local/share/megamplay/lib"
LinuxPackageMapping(
for {
  path <- (src ***).get
  if !path.isDirectory
} yield path -> path.toString.replaceFirst(src.toString, dest)
)
}

linuxPackageMappings in Debian <+= (baseDirectory) map { bd =>
  (packageMapping((bd / "conf/application-production.conf") -> "/usr/local/share/megamplay/conf/application-production.conf")
withConfig())
}

linuxPackageMappings in Debian <+= (baseDirectory) map { bd =>
  (packageMapping((bd / "conf/application-logger.xml") -> "/usr/local/share/megamplay/conf/application-logger.xml")
withConfig())
}

linuxPackageMappings in Debian <+= (baseDirectory) map { bd =>
(packageMapping((bd / "conf/routes") -> "/usr/local/share/megamplay/conf/routes")
withConfig())
}

linuxPackageMappings in Debian <+= (baseDirectory) map { bd =>
(packageMapping((bd / "conf/messages") -> "/usr/local/share/megamplay/conf/messages")
withConfig())
}

linuxPackageMappings in Debian <+= (baseDirectory) map { bd =>
(packageMapping((bd / "conf/play.plugins") -> "/usr/local/share/megamplay/conf/play.plugins")
withConfig())
}

com.typesafe.sbt.packager.debian.Keys.version in Debian <<= (com.typesafe.sbt.packager.debian.Keys.version, sbtVersion) apply { (v, sv) =>
sv + "-build-" + (v split "\." map (_.toInt) dropWhile (_ == 0) map ("%02d" format _) mkString "")
}

debianPackageDependencies in Debian ++= Seq("curl", "java2-runtime", "bash (>= 2.05a-11)")

debianPackageRecommends in Debian += "riak"

linuxPackageMappings <+= (baseDirectory) map { bd =>
packageMapping(
(bd / "copyright") -> "/usr/share/doc/megam_play/copyright"
) withPerms "0644" asDocs()
}

linuxPackageMappings in Debian <+= (com.typesafe.sbt.packager.debian.Keys.sourceDirectory) map { bd =>
(packageMapping(
(bd / "debian/changelog") -> "/usr/share/doc/megam_play/changelog.gz"
) withUser "root" withGroup "root" withPerms "0644" gzipped) asDocs()
}

mappings in upload := Seq((new java.io.File(("%s-%s.deb") format("target/megamplay", "0.12.4-build-0100")),"0.1/debs/megam_play.deb"))

host in upload := "megampub.s3.amazonaws.com"

credentials += Credentials(Path.userHome / "software" / "aws" / "keys" / "sbt_s3_keys")

S3.progress in S3.upload := true

1.Plugins.sb

// Comment to get more information during initialization
logLevel := Level.Warn

// The Typesafe repository
resolvers += "Typesafe repository" at     "https://repo.typesafe.com/typesafe/releases/"

// Typesafe snapshots
resolvers += "Typesafe Snapshots" at    "https://repo.typesafe.com/typesafe/snapshots/"

// Use the Play sbt plugin for Play projects

addSbtPlugin("play" % "sbt-plugin" % "2.2.0")

project/build.properties

sbt.version=0.13.0

We built our own AMQP based on scalaz, and is available in https://github.com/indykish/megam_common. Now build and publish megam_common jars using the process as described in this link into https://oss.sonatype.org/content/repositories/snapshots/com/github/indykish/megam_common_2.10/0.1.0-SNAPSHOT/.

sbt publish

Run the play project megam_play

ram@ramhome:~/code/megam/workspace/megam_play$ sbt
[info] Loading global plugins from /home/ram/.sbt/0.13/plugins
[info] Loading project definition from /home/ram/code/megam/workspace/megam_play/project
[info] Set current project to megam_play (in build     file:/home/ram/code/megam/workspace/megam_play/)
[megam_play] $ play
       _
  _ __ | | __ _ _  _
 | '_ | |/ _' | || |
 |  __/|_|___|__ /
 |_|          |__/

play 2.2.0 built with Scala 2.10.2 (running Java 1.7.0_25), https://www.playframework.com

> Type "help play" or "license" for more information.
> Type "exit" or use Ctrl+D to leave this console.

[megam_play] $

You can use lsof as shown below to see if the server runs on port 9000.

[nilam] $ run

$ sudo lsof -i:9000
[sudo] password for ram:
COMMAND   PID USER   FD   TYPE DEVICE SIZE NODE NAME
java    15640  ram  270u  IPv6  40094       TCP *:9000 (LISTEN)

Now let us add a template to show the

1. index page,
2. Error when an invalid URL is passed

####index.scala.html

@(message: String)(implicit flash: play.api.mvc.Flash)
@main("Megam Cloud v1") {
@welcome(message)
}

####main.scala.html

@(title: String)(content: Html)
<!DOCTYPE html>
<html>
<head>
<title>@title</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="">
<meta name="author" content="">
<link rel="stylesheet" type="text/css" href="https://fonts.googleapis.com/css?family=Lato:300,400,700" />
<link rel="stylesheet" type="text/css" href="@routes.Assets.at("stylesheets/theme.css")" >
<link rel="stylesheet" type="text/css" href="@routes.Assets.at("stylesheets/bootstrap-theme.css")" >
<link rel="stylesheet" type="text/css" href="@routes.Assets.at("stylesheets/bootstrap.css")" >
<link rel="stylesheet" type="text/css" href="@routes.Assets.at("stylesheets/bootstrap-glyphicons.css")">
<link rel="stylesheet" href="styles/default.css">
<link rel="stylesheet" type="text/css" href="@routes.Assets.at("stylesheets/styles/default.css")" >
<link rel="shortcut icon" type="image/png" href="@routes.Assets.at("images/favicon.png")">

<!-- Bootstrap -->
<script src="@routes.Assets.at("javascripts/jquery.js")" type="text/javascript"></script>
<script src="@routes.Assets.at("javascripts/bootstrap.js")" type="text/javascript"></script>
<script  src="@routes.Assets.at("javascripts/highlight.pack.js")" type="text/javascript"></script>

<script type="text/javascript">
        $(document).ready(function() {
            hljs.initHighlightingOnLoad();
            $('pre code').each(function(i, e) {
                hljs.highlightBlock(e)
            });
            $('a[data-toggle="tab"]').on('shown.bs.tab', function(e) {
                e.target// activated tab
                e.relatedTarget // previous tab
            });

        });
</script>
<style type="text/css">
  /* <![CDATA[ */
  #pagetoc li {
    padding-left: 22px;
    text-indent: -22px;
  }

  /* ]]> */
</style>
  </head>
   <body>
   <div>
    <div>
        @leftmenu()
        @content
    </div>
  </div>

<!-- JQuery will invoke via the spinner and display a loading modal lock. -->
<div id="loading" />

</body> </html>

####errorPage.scala.html

@(ex: Throwable)

@main("An error occurred while trying to run megam_play. contact support.") {
<div class="api-doc">
  <div class="mddoc margin-top-large">
   <image src="@routes.Assets.at("images/nirvana.png")"/>
<h1><a name="rest_docs" href="#a-rest_docs">Sucked into Nirvana</a></h1>
<p class="lead">
  <code>
    @(ex getMessage)
  </code>
</p>
<div class="page-header">
  <h2>Stacktrace</h2>
</div>

 <div class="">


<code class="brush: bash; toolbar:     false;">@({val u = new java.io.StringWriter; ex.printStackTrace(new java.io.PrintWriter(u)); u.toString})
    </code>
  </div>
 </div>
</div>
}


object Global extends GlobalSettings {

 override def onStart(app: Application) {
play.api.Logger.info("Megam Play %s App - started".format("0.1"))
}

override def onStop(app: Application) {
play.api.Logger.info("Megam Play %s App - going down. Stateless folks - you don't care.".format("0.1"))
}

override def onError(request: RequestHeader, ex: Throwable) : Future[play.api.mvc.SimpleResult] = {
Future.successful(InternalServerError(
  views.html.errorPage(ex)))
}

override def onHandlerNotFound(request: RequestHeader): Future[play.api.mvc.SimpleResult] = {
Future.successful(NotFound(
  views.html.errorPage(new Throwable(NOT_FOUND + ":" + request.path + " NOT_FOUND"))))
 }
}

Thee view files are placed under views directory.

Type https://localhost:9000