[Kea-users] get backup server into ready state

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[Kea-users] get backup server into ready state

oehlrich9
Hey everyone,

I'm setting up a ha cluster and wonder if there is a way to get a server, that is configured as a backup server, to transit into a ready state.
E.g. I have a monitoring instance that realizes that one of my kea instances fails and does not respond any more. Of course the service stays available as the second running kea instance takes over. But if my second instance would fail, there would be no working DHCP service available anymore.
I now want this monitoring service to automatically enable the backup server to take the place of the failed kea instance.

Can this be achieved without updating the config file just by using the REST backend?
It's not really documented what the backup server is for, besides to have a lease backup which can be turned on manually.

Cheers,
Benedikt

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Re: [Kea-users] get backup server into ready state

Dajka Tamás

Hi Benedikt,

 

I’m not really getting your idea of what you want to achieve, but let me provide you another possibility. Instead of running an active-backup KEA cluster run 2 kea servers with a common (and redundant) backend (mysql, pgsql, cassandra) and on the dhcp-relays (I assume you’ve one since you’re building something bigger) add both servers.

When a client’s request hits the relay the packet is relayed to the first KEA (or both), if there is no response, then to the second. Anyway one of them will respond.

Other possibility is to have one HA IP (VIP IP, VRRP IP) on the KEA cluster.

 

Hope this helps somehow.

 

Cheers,

 

               Tom

 

From: Kea-users [mailto:[hidden email]] On Behalf Of Oehlrich, Benedikt
Sent: Tuesday, January 14, 2020 7:45 AM
To: [hidden email]
Subject: [Kea-users] get backup server into ready state

 

Hey everyone,

 

I'm setting up a ha cluster and wonder if there is a way to get a server, that is configured as a backup server, to transit into a ready state.

E.g. I have a monitoring instance that realizes that one of my kea instances fails and does not respond any more. Of course the service stays available as the second running kea instance takes over. But if my second instance would fail, there would be no working DHCP service available anymore.

I now want this monitoring service to automatically enable the backup server to take the place of the failed kea instance.

Can this be achieved without updating the config file just by using the REST backend?

It's not really documented what the backup server is for, besides to have a lease backup which can be turned on manually.

 

Cheers,

Benedikt


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Re: [Kea-users] get backup server into ready state

oehlrich9
Hi Tom,

Thanks for your reply.
We tried the setup with a MySQL galera cluster and a dhcp relay sending to all 3 servers.
But we were not able to configure the isc dhcp relay in a way that it tries the servers after another.
It always sent the requests to all kea instances which caused the galera cluster to fall apart.

The overall goal is to run three kea instances so that two of them can fail and the dhcp service stays available.
If that can not be done with the kea ha itself, I will probably try the solution with the HA IP.

Thank you very much again 

Benedikt 

Dajka Tamás <[hidden email]> schrieb am Di. 14. Jan. 2020 um 09:02:

Hi Benedikt,

 

I’m not really getting your idea of what you want to achieve, but let me provide you another possibility. Instead of running an active-backup KEA cluster run 2 kea servers with a common (and redundant) backend (mysql, pgsql, cassandra) and on the dhcp-relays (I assume you’ve one since you’re building something bigger) add both servers.

When a client’s request hits the relay the packet is relayed to the first KEA (or both), if there is no response, then to the second. Anyway one of them will respond.

Other possibility is to have one HA IP (VIP IP, VRRP IP) on the KEA cluster.

 

Hope this helps somehow.

 

Cheers,

 

               Tom

 

From: Kea-users [mailto:[hidden email]] On Behalf Of Oehlrich, Benedikt
Sent: Tuesday, January 14, 2020 7:45 AM
To: [hidden email]
Subject: [Kea-users] get backup server into ready state

 

Hey everyone,

 

I'm setting up a ha cluster and wonder if there is a way to get a server, that is configured as a backup server, to transit into a ready state.

E.g. I have a monitoring instance that realizes that one of my kea instances fails and does not respond any more. Of course the service stays available as the second running kea instance takes over. But if my second instance would fail, there would be no working DHCP service available anymore.

I now want this monitoring service to automatically enable the backup server to take the place of the failed kea instance.

Can this be achieved without updating the config file just by using the REST backend?

It's not really documented what the backup server is for, besides to have a lease backup which can be turned on manually.

 

Cheers,

Benedikt


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