Dynamically loaded core.properties file

[Ryan Josal]

Hi all, I have a question about dynamically loading a core properties 
file with the new core discovery method of defining cores.  The concept 
is that I can have a dev.properties file and a prod.properties file, and 
specify which one to load with -Dsolr.env=dev.  This way I can have one 
file which specifies a bunch of runtime properties like external servers 
a plugin might use, etc.

Previously I was able to do this in solr.xml because it can do system 
property substitution when defining which properties file to use for a core.

Now I'm not sure how to do this with core discovery, since the core is 
discovered based on this file, and now the file needs to contain things 
that are specific to that core, like name, which previously were defined 
in the xml definition.

Is there a way I can plugin some code that gets run before any schema or 
solrconfigs are parsed?  That way I could write a property loader that 
adds properties from ${solr.env}.properties to the JVM system properties.

Thanks!
Ryan