rubygem-rack from openSUSE:Tools:2.0 project
Select Your Operating System
Add repository and install manually
For SLE 11 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/openSUSE:Tools:2.0/SLE_11/openSUSE:Tools:2.0.repo zypper refresh zypper install rubygem-rack