A REST PLAY FRAMEWORK APPLICATION EXAMPLE

Play Framework project using : Docker, Slick and REST.

The goal of that project is to exercice onto Scala Play.

Development

How to dockerize our Play application

To dockerize our application, we will use the sbt-native-packager plugin from SBT

1 - Add the depen­den­cies to your build.sbt :

// setting a maintainer which is used for all packaging types
maintainer := "Your name"

// exposing the play ports
dockerExposedPorts in Docker := Seq(9000, 9443)

2 - add sbt plugins to your /project/plugins.sbt :

addSbtPlugin("com.typesafe.sbt" %% "sbt-native-packager" % "1.0.4")

addSbtPlugin("se.marcuslonnberg" % "sbt-docker" % "1.2.0")

How to use Json parser of Play

Now, we want manipulate Json to a Json output. Play Framework contains a Json library.

In its part, we will work into the framework tree by adding a route and a controller.

First - we add route into route file

add the line into conf/routes :

GET     /hello                      controllers.Json.hello

We are defining a new route called /hello which will return a json like that :

{
	"message": "hello"
}

That route will be called by the GET HTTP method.

When the /hello is called, the action controllers.Json.hello is called, now we will create the hello action from Json controller

Second - Create an action which returns Json

Create a new file app/controllers/Json.scala and add next lines :

package controllers

import play.api._
import play.api.mvc._
import play.api.libs.json._

class Json extends Controller {

  def hello = Action {
    Ok(Json.obj("message" -> "hello"))
  }

}

Now, On your browser, taping http://localhost:9000/hello, it displays :

{
	"message": "hello"
}

see more with the Official documentation

Use Slick codegen

1. Add dependencies

For a SBT project add the following lines to your build definition file (build.sbt or project/Build.scala)

libraryDependencies ++= Seq(
  "com.typesafe.slick" %% "slick" % "3.1.0",
  "org.slf4j" % "slf4j-nop" % "1.6.4"
)

Now we add the Slick's code generator. For SBT projects add following to build definition ( = build.sbt)

libraryDependencies += "com.typesafe.slick" %% "slick-codegen" % "3.1.0"

If you want to use Mysql as Database Server, you must add Mysql connector dependency : libraryDependencies ++= Seq("mysql" % "mysql-connector-java" % "5.1.37") and "org.scala-lang" % "scala-reflect" % scala_version

2. Integrated to SBT

Add these lines into your build.sbt:

// Autogenerate Slick models
slick <<= slickCodeGenTask

//Used Code generator during compilation
//sourceGenerators in Compile <+= slickCodeGenTask

lazy val slick = TaskKey[Seq[File]]("gen-tables")
lazy val slickCodeGenTask = (sourceManaged, dependencyClasspath in Compile, runner in Compile, streams) map { (dir, cp, r, s) =>
  val outputDir = (dir / "app").getPath
  val username = "root"
  val password = "damien"
  val url = "jdbc:mysql://localhost/slick"
  val jdbcDriver = "com.mysql.jdbc.Driver"
  val slickDriver = "slick.driver.MySQLDriver"
  val pkg = "models"

  toError(r.run("slick.codegen.SourceCodeGenerator", cp.files, Array(slickDriver, jdbcDriver, url, outputDir, pkg, username, password), s.log))
  val fname = outputDir + "/" + "models" + "/Tables.scala"
  Seq(file(fname))
}

We created a SBT comand which create the file Tables.scala where there are all BDD models. The SBT command is :

sbt gen-tables

Tables.scala will be created into the path : target/scala-2.11/src_managed/app/models/

Compile

This file will be packaged with your application, when using activator dist.

Publishing Docker image :

sbt docker:publishLocal

To check if the image is really created you should tape this command :

docker images

If it's ok, you should see one line with

Run the application

To run project via Docker:

docker run --name play-8080 -p 8080:9000 [your-app-name:[your-app-version]

With the previous command, we run the docker image, the options -p to expose port 9000 outside Docker’s virtual network (that’s locally available as 8080)

You can go to the application with your favorite browser by taping http://localhost:8080