My use case is as follows:

I have a parameterized build (freestyle project) and I would like to be able to decide, based on the parameters selected by the user, whether to tag the build or not.

The only solution I found involves the use of the "Environment Script Plugin" to inject an environment variable in the build process and then pick it up with the tagging plugin.

Roughly:

(1) The environment script configuration looks like this ("Generate environment variables from script")

if some_condition; then
echo BUILD_TAG_URL="http://my.svn.server/repo/tags/$NAME/Build-$BUILD_NUMBER"
else
echo BUILD_TAG_URL="<do_not_tag_me>"
fi

(2) The configuration for subversion tagging looks like this:

tag_base_url = ${env['BUILD_TAG_URL']}

It works, in the sense that the tagging obviously fails when the tag URL is set to something plain invalid like "<do_not_tag_me>".

I was wondering if you could put together a more elegant solution to conditional tagging; could be as simple as not tagging a build if the tag base URL expands to an empty string (my case), or something more elaborate (tag or not, based on a condition).