[jetty-users] Understanding Property tag use

[Peter Boughton <jetty@xxxxxxxxxxxxxxxxx>]

I'm trying to understand the relationship between start.ini parameters and the <Property> tag.

What I thought was the case (and this is backed up by the `start.jar --help` text) is that any a=b lines in start.ini can be referred to from an XML config file as <Property name="a" /> to use "b" in that value.

An example being jetty.http.port which can be set in start.ini and appears to pass the value through in jetty-http.xml with:
	<Set name="port"><Property name="jetty.http.port" deprecated="jetty.port" default="8080" /></Set>

However, when trying to use the same in WebAppContext with resourceBase, I get the default (not the ini value):
	<Set name="resourceBase"><Property name="jetty.http.port" deprecated="jetty.port" default="8080" />/path</Set>

Likewise, setting my.property=something in start.ini the following property is replaced by the string "null" (or the default if one is added), instead of the expected "something":
	<Set name="resourceBase"><Property name="my.property" />/path</Set>

If I use -Dmy.property=something and switch from Property to SystemProperty tag it works as expected.
If I use Property tag with name="jetty.base" it also resolves as expected.

The documentation at https://www.eclipse.org/jetty/documentation/current/jetty-xml-usage.html says that the Property tag is for .properties files, but doing `echo "my.property=something" > myjetty.properties` and passing the file to start.jar still ends up with null/default. (However, adding jetty.http.port to myjetty.properties does change the port.)

So, can anyone explain what I'm missing?