Substitutions not occurring with Typesafe Config

When I use Config.withValue to create an updated config, substitutions are not re-evaluated, even with a call to resolve:

application.conf:

zooKeeperAddr = "localhost:2181"
zooKeeperAddr2 = ${zooKeeperAddr}

Application code:

  val config = ConfigFactory.load()
                .withValue("zooKeeperAddr", ConfigValueFactory.fromAnyRef("abc"))
                .resolve;

  val zooKeeperAddr = config.getAnyRef("zooKeeperAddr")
  val zooKeeperAddr2 = config.getAnyRef("zooKeeperAddr2")
  println(s"zooKeeperAddr, zooKeeperAddr2 is $zooKeeperAddr, $zooKeeperAddr2")

I expect, of course, to see

 zooKeeperAddr, zooKeeperAddr2 is abc, abc

But what I see instead is:

 zooKeeperAddr, zooKeeperAddr2 is abc, localhost:2181

How can I get substitutions re-evalauted?

(The larger issue is, I'm trying to inject command-line arguments, in particular, Twitter Module Flags, into the Typesafe Config. Perhaps there's a better way to achieve this goal?

My actual code is:

    val config = flag.getAll(false).foldLeft(ConfigFactory.load()){
      case (conf, f) if f.isDefined => conf.withValue(f.name, ConfigValueFactory.fromAnyRef(f.get.get))
      case (conf, _) => conf
     }.resolve

)

Solution

So I (the OP) ended up doing the following:

  val config = flag.getAll(false).foldLeft(ConfigFactory.empty()){
      case (conf, f) if f.isDefined => conf.withValue(f.name, ConfigValueFactory.fromAnyRef(f.get.get))
      case (conf, _) => conf
    }
    .withFallback(ConfigFactory.defaultOverrides())
    .withFallback(ConfigFactory.defaultApplication())
    .withFallback(ConfigFactory.defaultReference())
    .resolve

flag.getAll returns an Iterable[com.twitter.app.Flag]; for each flag that isDefined, we add it to an initaily empty config (ConfigFactory.empty()).

Then we withFallback to, in order, the default overrides (the settings properties), the application config (application.conf, and the default reference (which should include, I hope, all reference.confs in all jars).

withFallback, according to its documentation, "Returns a new value computed by merging this value with another, with keys in this value "winning" over the other one."

Finally, we resolve.

This seems to propagate the substitutions as I want, but I can't help but think the Config API provides an easier way to do this.