For SLE 15 SP3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:interstar001:Icinga2/SLE_15_SP3/home:interstar001:Icinga2.repo
zypper refresh
zypper install icinga2
For SLE 15 SP2 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:interstar001:Icinga2/SLE_15_SP2/home:interstar001:Icinga2.repo
zypper refresh
zypper install icinga2
For SLE 15 SP1 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:interstar001:Icinga2/SLE_15_SP1/home:interstar001:Icinga2.repo
zypper refresh
zypper install icinga2
For SLE 12 SP5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:interstar001:Icinga2/SLE_12_SP5/home:interstar001:Icinga2.repo
zypper refresh
zypper install icinga2