original bz: https://bugzilla.redhat.com/show_bug.cgi?id=1944864

you can use the "networks" parameter in rgw specs. this will allow the rgw service to bind to a certain network. this option needs to be documented.  

example

>>> [ceph: root@vm-00 /]# cat spec.yml 
>>> service_type: rgw 
>>> service_id: rgws 	
>>> placement: 
>>>   hosts: 
>>>     - vm-00
>>> rgw_frontend_port: 8080
>>> unmanaged: false
>>> networks:
>>>   - 192.169.142.0/24
>>> 
>>> [ceph: root@vm-00 /]# 
>>> [ceph: root@vm-00 /]# ceph orch apply -i spec.yml 
>>> Scheduled rgw.rgws update...
>>> [ceph: root@vm-00 /]# 
>>> [ceph: root@vm-00 /]# 
>>> [ceph: root@vm-00 /]# 
>>> [ceph: root@vm-00 /]# 
>>> [ceph: root@vm-00 /]# ceph orch ps
>>> NAME                   HOST   STATUS         REFRESHED  AGE  PORTS                 VERSION  IMAGE ID      CONTAINER ID  
>>> alertmanager.vm-00     vm-00  running (8m)   12s ago    11m  *:9093 *:9094         0.20.0   0881eb8f169f  e40ee34a9c57  
>>> crash.vm-00            vm-00  running (11m)  12s ago    11m  -                     16.2.0   24ecd6d5f14c  327d4d2be921  
>>> crash.vm-01            vm-01  running (9m)   6m ago     9m   -                     16.2.0   24ecd6d5f14c  def40f9f9892  
>>> crash.vm-02            vm-02  running (9m)   5m ago     9m   -                     16.2.0   24ecd6d5f14c  ac13280df800  
>>> grafana.vm-00          vm-00  running (8m)   12s ago    10m  *:3000                6.7.4    80728b29ad3f  df9d10fff33a  
>>> mgr.vm-00.gnkuyx       vm-00  running (12m)  12s ago    12m  *:9283                16.2.0   24ecd6d5f14c  f5468d40dbb0  
>>> mgr.vm-02.ikrzpu       vm-02  running (9m)   5m ago     9m   *:8443 *:9283         16.2.0   24ecd6d5f14c  1d9525b7cef9  
>>> mon.vm-00              vm-00  running (12m)  12s ago    12m  -                     16.2.0   24ecd6d5f14c  63a2e71364fb  
>>> mon.vm-01              vm-01  running (9m)   6m ago     9m   -                     16.2.0   24ecd6d5f14c  fe04212105a4  
>>> mon.vm-02              vm-02  running (9m)   5m ago     9m   -                     16.2.0   24ecd6d5f14c  6f670ac3fa2b  
>>> node-exporter.vm-00    vm-00  running (10m)  12s ago    10m  *:9100                0.18.1   e5a616e4b9cf  1d016351c587  
>>> node-exporter.vm-01    vm-01  running (8m)   6m ago     8m   *:9100                0.18.1   e5a616e4b9cf  7636b7f36e5e  
>>> node-exporter.vm-02    vm-02  running (8m)   5m ago     8m   *:9100                0.18.1   e5a616e4b9cf  63910bf9e82f  
>>> osd.0                  vm-00  running (8m)   12s ago    8m   -                     16.2.0   24ecd6d5f14c  f6a2c5da6474  
>>> osd.1                  vm-02  running (8m)   5m ago     8m   -                     16.2.0   24ecd6d5f14c  f5d67a805c1a  
>>> osd.2                  vm-01  running (8m)   6m ago     8m   -                     16.2.0   24ecd6d5f14c  e68b84ae9a6a  
>>> prometheus.vm-00       vm-00  running (8m)   12s ago    10m  *:9095                2.18.1   de242295e225  c3d12d8fcfdc  
>>> rgw.rgws.vm-00.rtdtvj  vm-00  running (14s)  12s ago    14s  192.169.142.239:8080  16.2.0   24ecd6d5f14c  90805c69001e  
>>> [ceph: root@vm-00 /]# 
>>> [ceph: root@vm-00 /]# 
>>> [ceph: root@vm-00 /]# 
>>> [ceph: root@vm-00 /]# 
>>> [ceph: root@vm-00 /]# 
>>> [ceph: root@vm-00 /]# 
>>> [ceph: root@vm-00 /]# exit
>>> [root@vm-00 ~]# 
>>> [root@vm-00 ~]# 
>>> [root@vm-00 ~]# 
>>> [root@vm-00 ~]# curl 192.169.142.239:8080
>>> <?xml version="1.0" encoding="UTF-8"?><ListAllMyBucketsResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/"><Owner><ID>anonymous</ID><DisplayName></DisplayName></Owner><Buckets></Buckets></ListAllMyBucketsResult>[root@vm-00 ~]#