[Kea-users] HA hot-standby query role

Arne Baeumler arne+kea at br0tkasten.de
Wed Oct 24 15:07:39 UTC 2018


Hi,

we are about to setup two kea dhcp servers running libdhcp_ha in 
hot-standby mode (cfg. ha-library config below).


{
                                 "library": 
"/opt/kea-latest/lib/hooks/libdhcp_ha.so",
                                 "parameters": {
                                         "high-availability": [ {
                                                 "this-server-name": 
"dhcp-hsi4.uni",
                                                 "mode": "hot-standby",
                                                 "heartbeat-delay": 
10000,
                                                 "max-response-delay": 
60000,
                                                 "max-unacked-clients": 
0,
                                                 "send-lease-updates": 
false,
                                                 "sync-leases": false,
                                                 "peers": [
                                                         {
                                                                 "name": 
"dhcp-hsi4.rz2",
                                                                 "url": 
"http://172.16.51.153:8080/",
                                                                 "role": 
"primary",
                                                                 
"auto-failover": true
                                                         },
                                                         {
                                                                 "name": 
"dhcp-hsi4.uni",
                                                                 "url": 
"http://172.16.51.154:8080/",
                                                                 "role": 
"standby",
                                                                 
"auto-failover": true
                                                         }
                                                 ]
                                         } ]
                                 }
}


According to our tests, lease-updates using kea's HA protocol do not 
perform very well with >70 requests/sec.
Therefore we configured lease replication in our db backend 
(postgresql).
To get synchronization direction correct (sync leases from active -> 
standby) we need to query the state/role of both servers.

The API command ha-heartbeat returns state: 'hot-standby' on both 
servers.

$ /usr/bin/curl -s -X POST -H "Content-Type: application/json" -d '{ 
"command": "ha-heartbeat", "service": [ "dhcp4" ] }' 
http://172.16.51.154:8080/ | jq -r '.'
[
   {
     "arguments": {
       "date-time": "Wed, 24 Oct 2018 14:18:39 GMT",
       "state": "hot-standby"
     },
     "result": 0,
     "text": "HA peer status returned."
   }
]



Is there an API call returning wether the server is actually processing 
(role: primary) or ignoring (role: standby) dhcp messages?



-- 
best regards,
Arne


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