Simple Scala FlywayServlet

ScalaFlywayServlet.scala

class FlywayServlet extends javax.servlet.http.HttpServlet {

  private val logger: Logger = LoggerFactory.getLogger(classOf[FlywayServlet])

  //declaring globally so we can potentially make this an Schema Admin Servlet which can
  //repair, destroy, migrate the schema
  private val flyway: Flyway = {
    //unclear if DriverDataSource is an internal class
    //flyway example on google code uses it so I decided to as well
    //avoids having to explicitly create properties object and put
    //values for flyway properties
    //the second parameter to GlobalProperties is a default value, avoiding hardcoding of user and pwd

    val ds: DataSource = new DriverDataSource(
      GlobalProperties.get("datasource.pg.databaseDriver", "org.postgresql.Driver"),
      GlobalProperties.get("datasource.pg.databaseUrl", "jdbc:postgresql://localhost/apps"),
      GlobalProperties.get("datasource.pg.username", ""),
      GlobalProperties.get("datasource.pg.password", ""),
      "select 1"
    )

    val flyway: Flyway = new Flyway()
    flyway.setDataSource(ds)
    //setting this to true - flyway recommends not to so that if you accidentally apply it to the wrong schema
    //the schema will be untouched.  But without it you have to manually run init
    //we can take this out in the future - once it has been applied

    // we will set this to false once init has been run once
    // shouldnt harm anything if it gets run multiple times but lets avoid it
    flyway.setInitOnMigrate(true)
    flyway
  }

  override def init() {
    migrate()
  }

  override def doGet(request: HttpServletRequest, response: HttpServletResponse) {
    response.setContentType("text/html")
    val resp = invokeAction(request.getParameter("action"))
    response.getOutputStream.print(resp)
  }

  def invokeAction(action: String): String = action match {
    //doing nothing on migrate because init is always called
    case "migrate" => ""
    case "version" => version
    case _ => "Unknown action"
  }

  /**
   * call migrate and then switch of default initialization
   * @return
   */
  def migrate(): String = {
    val cnt = flyway.migrate
    // we will set this to false once init has been run once
    // shouldn't harm anything if it gets run multiple times but lets avoid it
    flyway.setInitOnMigrate(false)

    val resp: String = "Migrations applied: " + cnt
    logger.info(resp)
    resp
  }

  /**
   *
   * Should ideally create an xhtml page that fills out this information
   * @return html response string
   */
  def version(): String = {
    val sb: StringBuilder = new StringBuilder
    sb.append("<table style='border: 1px solid black;'>")
    sb.append("<tr style='border: 1px solid black;'>")
    sb.append("<td style='border: 1px solid black;'><b>DESCRIPTION </td>")
    sb.append("<td style='border: 1px solid black;'><b>VERSION</td>")
    sb.append("<td style='border: 1px solid black;'><b>SCRIPT</td>")
    sb.append("<td style='border: 1px solid black;'><b>STATE</td>")
    sb.append("<td style='border: 1px solid black;'><b>TYPE</td>")
    sb.append("<td style='border: 1px solid black;'><b>INSTALLED ON</td>")

    for (arg <- flyway.info.all) {
      sb.append("<tr style='border: 1px solid black;'>")
      sb.append("<td style='border: 1px solid black;'>" + arg.getDescription + "</td>")
      sb.append("<td style='border: 1px solid black;'>" + arg.getVersion + "</td>")
      sb.append("<td style='border: 1px solid black;'>" + arg.getScript + "</td>")
      sb.append("<td style='border: 1px solid black;'>" + arg.getState + "</td>")
      sb.append("<td style='border: 1px solid black;'>" + arg.getType + "</td>")
      sb.append("<td style='border: 1px solid black;'>" + arg.getInstalledOn + "</td>")
      sb.append("</tr>")
    }
    sb.append("</table>")
    sb.toString()
  }
}