Here a very small example. One host on the remote site
Name: example
IP: 172.24.255.29
Config Dump - faraway.mk
# Created by /omd/sites/faraway/bin/cmcdump -C
shadow_hosts.update({'example': {'alias': 'example', 'address': '172.24.255.29', 'parents': [], 'check_command': 'check-mk-host-smart', 'check_command_expanded': 'check-mk-host-smart!', 'check_period': '24X7', 'check_interval': 0.1, 'contact_groups': ['all'], 'custom_variables': {'TAGS': '/wato/ auto-piggyback ip-v4 ip-v4-only lan no-agent no-snmp ping prod site:faraway', 'ADDRESS_6': '', 'ADDRESSES_6': '', 'ADDRESS_4': '172.24.255.29', 'ADDRESS_FAMILY': '4', 'ADDRESSES_4': '', 'FILENAME': '/wato/hosts.mk'}, 'first_notification_delay': 0, 'flap_detection_enabled': 1, 'groups': ['check_mk'], 'max_check_attempts': 1, 'notification_interval': 0, 'notification_period': '24X7', 'notifications_enabled': 1, 'process_performance_data': 0, 'retry_interval': 0.1, 'service_period': '24X7', 'services': [{'description': 'PING', 'check_command': 'check-mk-ping!-w 200.00,80.00% -c 500.00,100.00% 172.24.255.29', 'check_command_expanded': 'check-mk-ping!-w 200.00,80.00% -c 500.00,100.00% 172.24.255.29', 'check_period': '24X7', 'check_interval': 1, 'contact_groups': ['all'], 'custom_variables': {}, 'first_notification_delay': 0, 'flap_detection_enabled': 1, 'groups': [], 'max_check_attempts': 1, 'notification_interval': 0, 'notification_period': '24X7', 'notifications_enabled': 1, 'process_performance_data': 1, 'retry_interval': 1, 'service_period': '24X7'}]}})
After copy to the central site a “cmk --debug -vvR” produce the following output.
Trying to acquire lock on /omd/sites/central/etc/check_mk/main.mk
Got lock on /omd/sites/central/etc/check_mk/main.mk
Generating configuration for core (type cmc)...
Trying to acquire lock on /omd/sites/central/var/check_mk/core/helper_config/serial.mk
Got lock on /omd/sites/central/var/check_mk/core/helper_config/serial.mk
Releasing lock on /omd/sites/central/var/check_mk/core/helper_config/serial.mk
Released lock on /omd/sites/central/var/check_mk/core/helper_config/serial.mk
time period '24X7': 2 time points
Starting full compilation for all hosts Creating global helper config...OK
Creating cmc protobuf configuration...
WARNING: Cannot lookup IP address of 'example' (Failed to lookup IPv4 address of example via DNS: [Errno -3] Temporary failure in name resolution). The host will not be monitored correctly.
Trying to acquire lock on /omd/sites/central/var/check_mk/core/helper_config/2/core_host_config/example
Got lock on /omd/sites/central/var/check_mk/core/helper_config/2/core_host_config/example
Releasing lock on /omd/sites/central/var/check_mk/core/helper_config/2/core_host_config/example
Released lock on /omd/sites/central/var/check_mk/core/helper_config/2/core_host_config/example
Trying to acquire lock on /omd/sites/central/var/check_mk/core/helper_config/2/helper_cache_info
Got lock on /omd/sites/central/var/check_mk/core/helper_config/2/helper_cache_info
Releasing lock on /omd/sites/central/var/check_mk/core/helper_config/2/helper_cache_info
Released lock on /omd/sites/central/var/check_mk/core/helper_config/2/helper_cache_info
OK
/omd/sites/central/var/nagios/retention.dat not found, not importing Nagios state./omd/sites/central/var/check_mk newer than /omd/sites/central/var/nagios/retention.dat, not importing Nagios state./omd/sites/central/var/check_mk/core/config.pb written.
Restarting monitoring core...OK
Releasing lock on /omd/sites/central/etc/check_mk/main.mk
Released lock on /omd/sites/central/etc/check_mk/main.mk
On this central site was no host existing an nothing configured. The site was completely new created.
The single host itself is correctly shown as a shadow host inside the central site. But the IP lookup takes a huge amount of time in bigger production systems.