title: Specify pom properties via a properties file?
body: <p>Due to the way my build system is designed (RTC Build Engine), I would like to provide maven with property values via a properties file, instead of specifying -Dkey=value for every property.</p>
  
  <p>I found a couple of questions on S.O. (<a href="https://stackoverflow.com/q/12082277/827480">How to set build properties from a file in Maven POM?</a> and <a href="https://stackoverflow.com/q/849389/827480">How to read an external properties file in Maven</a>) that relate precisely to this question, but they are relatively old, and both require custom plugins to work (in alpha state).</p>
  
  <p>I realize that passing parameters to Maven like this is probably not the best solution, but the other option is specifying everything on the command line via -D settings which is not ideal either.  </p>
  
  <p>Furthermore, given that this properties file is only really used by the build engine (and not by the individual developer), I don't truly believe it belongs in the pom.  But I cannot find any other mechanism that would allow me to specify a plugin to use - settings.xml does not permit specifying plugins.</p>
  
  <p>Is my only choice in this case to use a plugin and specify it in the project pom?</p>