Scala Jetty webapp on Heroku 404 - scala

Question

I'm testing around with a Scala web framework (Udash) and trying to run a toy-example in Heroku. I have it running without issues in local following the instructions in the Heroku docs:
sbt compile stage
heroku local web
However, once deployed, any URL I type goes to 404, even the landing page of the app. These are the objects I am using:
object Launcher extends CrossLogging {
def main(args: Array[String]): Unit = {
val port = Properties.envOrElse("PORT", "5000").toInt
val server = new ApplicationServer(port, "frontend/target/UdashStatics/WebContent")
server.start()
logger.info(s"Application started...")
}
}
class ApplicationServer(val port: Int, resourceBase: String) {
private val server = new Server(port)
private val contextHandler = new ServletContextHandler
private val appHolder = createAppHolder()
contextHandler.setSessionHandler(new SessionHandler)
contextHandler.setGzipHandler(new GzipHandler)
contextHandler.getSessionHandler.addEventListener(new org.atmosphere.cpr.SessionSupport())
contextHandler.addServlet(appHolder, "/*")
server.setHandler(contextHandler)
def start(): Unit = server.start()
def stop(): Unit = server.stop()
private def createAppHolder() = {
val appHolder = new ServletHolder(new DefaultServlet)
appHolder.setAsyncSupported(true)
appHolder.setInitParameter("resourceBase", resourceBase)
appHolder
}
}
Is there any Heroku configuration/characteristic that I am missing?
EDIT
Tried to apply the changes suggested and ended up with the following ApplicationContext:
class ApplicationServer(val port: Int, val resourceBase: String) {
val server = new Server()
val connector = new ServerConnector(server)
connector.setPort(port)
server.addConnector(connector)
private val appHolder = createAppHolder()
val context = new ServletContextHandler(ServletContextHandler.SESSIONS)
context.setBaseResource(Resource.newResource(resourceBase))
context.setContextPath("/")
context.addServlet(appHolder, "/")
server.setHandler(context)
private def createAppHolder() = {
val appHolder = new ServletHolder("default", classOf[DefaultServlet])
appHolder.setInitParameter("dirAllowed", "true")
appHolder.setInitParameter("resourceBase", resourceBase)
appHolder
}
def start(): Unit = server.start()
def stop(): Unit = server.stop()
}
However, I still get Error 404 even on landing page after deploying to Heroku:
HTTP ERROR 404
Problem accessing /. Reason:
Not Found
When running the app on local I get to the landing page correctly.
Thank you!
Thanks!

Answer 1

A few things to adjust that might help you.
resourceBase as a init-parameter on DefaultServlet is for alternate static file serving.
Use ServletContextHandler.setBaseResource(Resource) instead.
Use Resource.newResource(String) to create a new Resource reference. This should be an absolute path on the filesystem, or an absolute URI reference. no relative paths or URI fragments.
The DefaultServlet must be on the url-pattern of "/", not "/*" (this is a servlet spec requirement)
The DefaultServlet must be named, and must have the name "default" (this is a servlet spec requirement, see link on point 1 for example)
set the ServletContextHandler.setContextPath("/") to be explicit about what base context-path you want to use.
Some observations:
Your example code will only serve static content out of the resourceBase.
Since you have no welcomeFiles configured it would serve <resourceBase>/index.html by default (if you don't specify a specific static resource you want to access)
You have a SessionListener setup (org.atmosphere.cpr.SessionSupport), but since there's nothing that would access a Session, that code is pretty much a no-op.
There's no dynamic results from a custom Servlet or Filter present in your example codebase.