How do I properly fix deploy permission issues with Hudson and ant?

Question

I'm having trouble deploying my Web start to the web server due to permissions problems (reformatted):

/home/hudson/.../build/build-web-start.xml:20: Failed to copy
/home/hudson/.../dist/app.jnlp to 
/var/development/.../webstart/app.jnlp due to java.io.FileNotFoundException
/var/development/.../webstart/app.jnlp (Permission denied) 
and I couldn't delete the corrupt /var/development/.../webstart/app.jnlp

...so it's obvious what the problem is. I need to do one of the following:

• Find the build user so that I can give it permissions
• Configure hudson to build the app under a specific user (perhaps separating the deploy from the rest of the build)
• Configure the ant build script to execute the deploy under a specific user.

Current situation:

• I'm running Hudson under jetty
• I've given the jetty user group permissions to be able to write to the deploy folder
• HUDSON_HOME is set to /home/hudson

Answer 1

The etc/init.d/jetty startup script contains the line (by default)

JETTY_USER=jetty

so...

chown jetty /var/development/.../webstart -R

does the trick.

NB: In particular, this highlights that setting jetty's group permissions to be able to write to the directory is not enough: jetty runs it's context under jetty:nogroup; e.g. it has no group.