Для openSUSE 12.3 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/OBS:Server:2.4/openSUSE_12.3/OBS:Server:2.4.repo
zypper refresh
zypper install rubygem-rack-cache-1_2
Для openSUSE 12.2 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/OBS:Server:2.4/openSUSE_12.2/OBS:Server:2.4.repo
zypper refresh
zypper install rubygem-rack-cache-1_2
Для openSUSE 12.1 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/OBS:Server:2.4/openSUSE_12.1/OBS:Server:2.4.repo
zypper refresh
zypper install rubygem-rack-cache-1_2