如何重用Typesafe配置文件中的属性？

Question

Consider following files:

application.conf

app {
    port = 5000
}

reference.conf

akka {
    cluster {
        seed-nodes = ["akka.tcp://sysName@localhost:"${app.port}]
    }
}

So when I run ConfigFactory.load() it fails, because ${app.port} does not present in reference.conf.

But load algorithm is clear - reference.conf is loaded and merged with application.conf . Is there a way to load application.conf and "include" reference.conf into it?

IMPORTANT

I tried add include "reference.conf" at the first line in application.conf it does not help.

Answer 1

You can use file("") syntax to include file.

include file("reference.conf")

see https://github.com/typesafehub/config/blob/master/HOCON.md#include-syntax

Answer 2

According to Typesafe Config documentation :

The implication of this is that the reference.conf stack has to be self-contained; you can't leave an undefined value ${foo.bar} to be provided by application.conf , or refer to ${foo.bar} in a way that you want to allow application.conf to override. However, application.conf can refer to a ${foo.bar} in reference.conf .

The documentation also lists some possible workarounds:

• putting an application.conf in a library jar, alongside the reference.conf , with values intended for later resolution.
• putting some logic in code instead of building up values in the config itself.