Configuring the ConfigFactory

There isn’t much to configure in OWNER since most of the things are done via annotations.

Still somebody recently asked: I need to decide the sources locations at runtime, is it possible to pass them explicitly? (Issue #36 on GitHub).

The short answer was no, even though there was some options to work around this limit.

But at the end, we agreed to add some configuration properties to configure the OWNER ConfigFactory itself.

Let’s take this as example:

// notice ${mypath} here
@Sources("file:${mypath}/myconfig.properties");
interface MyConfig extends Config { ... }

MyConfig cfg = ConfigFactory.create(MyConfig.class);

The variable ${mypath} would be expanded from the System properties or from the environment properties, if defined there. But this isn’t convenient enough: environment properties are read only, and sometimes it is not convenient to change system properties, especially for applications deployed in shared JVMs.

So OWNER does have some context properties associated to the ConfigFactory itself:

// notice ${mypath} here
@Sources("file:${mypath}/myconfig.properties");
interface MyConfig extends Config { ... }

// notice ${mypath} here
ConfigFactory.setProperty("mypath", "/foo/bar/baz");
MyConfig cfg = ConfigFactory.create(MyConfig.class);

When the create() method is executed the “file:${mypath}/myconfig.properties” specified by @Sources will be expanded to “file:/foo/bar/baz/myconfig.properties”.

Notice that, if you later change the value in the ConfigFactory and try to reload the Config object, this will not be affected, since the config object works on a snapshot of the those properties generated when the create() method is invoked.

Nothing prevents you to do something like:

// notice ${myurl} here
@Sources("${myurl}");
interface MyConfig extends Config { ... }

// notice ${myurl} here
ConfigFactory.setProperty(
  "myurl", "http://somewhere.com/conf.properties");
MyConfig cfg = ConfigFactory.create(MyConfig.class);

You are completely free to define the sources of your configuration at runtime.

Back