[Kea-users] HA setup in kubernetes, hostnames in the configuration fail to resolve

[Yordanov, Damyan]

Hello everyone,

I am running an HA (hot standby) Kea setup in Kubernetes. I do not want to hard-code service IPs, so I switched to headless services instead, hoping to be able to provide (fest) hostnames in the HA configuration:

[…]
"parameters": {
  "high-availability": [
    {
      "this-server-name": "secondary",
      "mode": "hot-standby",
      "heartbeat-interval": 10000,
      "max-response-delay": 60000,
      "max-ack-delay": 10000,
      "max-unacked-messages": 0,
      "max-unacked-clients": 0,
      "peers": [
        {
            "name": "primary",
            "url": "http://dhcp-prim-headless-svc:8000/“,  <- does not seem to be supported
            "role": "primary",
            "auto-failover": true
        },
        {
            "name": "secondary",
            "url": "http://dhcp-second-headless-svc:8000/“, <- same here
            "role": "standby",
            "auto-failover": true
        }
      ]
    }
  ]
}
[…]

However, the Kea container fails to start with the error message that the address cannot be resolved:

363 18:16:52.313 kea-dhcp4.hooks HOOKS_STD_CALLOUT_REGISTERED hooks library /usr/lib/x86_64-linux-gnu/kea/hooks/libdhcp_ha.so registered standard callout for hook leases4_committed at address 0x7f20d4739360
363 18:16:52.313 kea-dhcp4.ha-hooks HA_CONFIGURATION_FAILED failed to configure High Availability hooks library: bad url 'http://dhcp-prim-headless-svc:8000/': Failed to convert string to address 'dhcp-prim-headless-svc<http://dhcp-prim-headless-svc:8000/':%20Failed%20to%20convert%20string%20to%20address%20'dhcp-prim-headless-svc>': Invalid argument for server primary
363 18:16:52.313 kea-dhcp4.hooks HOOKS_LOAD_ERROR 'load' function in hook library /usr/lib/x86_64-linux-gnu/kea/hooks/libdhcp_ha.so returned error 1

The headless service is perfectly pingable from other containers in the pod, so no DNS general problem there.

I also stumbled upon a unit test, indicating that hostnames are not supported in the configuration, https://gitlab.isc.org/isc-projects/kea/-/blob/master/src/hooks/dhcp/high_availability/tests/ha_config_unittest.cc#L651-L677. However, the HA design document, https://gitlab.isc.org/isc-projects/kea/-/wikis/designs/High-Availability-Design,<https://gitlab.isc.org/isc-projects/kea/-/wikis/designs/High-Availability-Design,has> clearly *has* hostnames in its showcase configuration.

So, can someone, kindly, hint me if that’s supported or not? If the latter is the case, I will just open a feature request.

For the developers: thanks for the great work, keep it up!

Best,
   Damyan Y.


Damyan Yordanov

BTP Core FP R&C Gardener (SE)

SAP SE, Dietmar-Hopp-Allee 16, 69190 Walldorf, Germany

T +49 6227 7-65764, M +49 160 90 842 652, damyan.yordanov at sap.com<mailto:damyan.yordanov at sap.com>


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