For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:dmolkentin:infrarun/openSUSE_Tumbleweed/home:dmolkentin:infrarun.repo
zypper refresh
zypper install golang-github-prometheus-alertmanager
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:dmolkentin:infrarun/15.5/home:dmolkentin:infrarun.repo
zypper refresh
zypper install golang-github-prometheus-alertmanager
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:dmolkentin:infrarun/15.4/home:dmolkentin:infrarun.repo
zypper refresh
zypper install golang-github-prometheus-alertmanager