scala- error loading a properties file packed inside jar

Question

This is a newbie question, I read a lot but I am a bit confused.

I pass a properties file from inside a Jar, configuration is read, all is fine.

I wanted to add a try catch.I tried this but it does not work because the loading does not produce an exception if the properties file is not present. Therefore 3 questions:

• Is it correct to load files like this?
• Does it make sense to put a try/catch since the config is inside the jar?

• If so, any suggestions on how to?

  var appProps : Config = ConfigFactory.load()
  try { 
    appProps = ConfigFactory.load("application.properties") 
  } catch {
    case e: Exception => {
      log.error("application.properties file not found")
      sc.stop()
      System.exit(1)
    }
  }
  

Answer 1

Your code looks ok in general.

ConfigFactory.load("resource.config") will handle a missing resource like an empty resource. As a result you get an empty Config. So, a try-catch-block does not really make sense.

You would usually specify a fallback configuration like this:

val appProps = ConfigFactory.load(
  "application.properties"
).withFallBack(
   ConfigFactory.load()
)

EDIT:

The sentence

As a result you get an empty Config

Is somewhat incomplete. ConfigFactory.load(resourceBaseName: String) applies defaultReference() and defaultOverrides(). So your resulting Config object probably contains some generic environment data and is not empty.

As far as I can see, your best option to check if the resource is there and emit an error message if not, is to look up the resource yourself:

  val configFile = "application.properties"
  val config = Option(getClass.getClassLoader.getResource(configFile)).fold {
    println(s"Config not found!")
    ConfigFactory.load()
  } { resource =>
    ConfigFactory.load(configFile)
  }