I've added a configuration parameter to a build configuration on a team city instance called "client".
This parameter is supplied every build, and can be viewed under the header User Defined Parameters and Actual Parameters on Agent in the parameters tab for a given a build (along with all the other parameters e.g. build.number, teamcity.project.id etc).
I can access this parameter for a build with -
server:port/httpAuth/app/rest/builds/id:xxx/resulting-properties/client
Let's say I went to get all builds where the client is Google. I have the build configuration id if that helps any.
I've searched high and low in the documentation. Is this possible?