[lvs-users] keepalived: can it be used in cloud environment?

Gerry Reno greno at verizon.net
Thu Jan 14 02:02:04 GMT 2010


Siim Põder wrote:
> Hi
>
> Gerry Reno wrote:
>   
>> How can I use keepalived in a highly dynamic cloud environment?  How can 
>> I keep keepalived.conf up-to-date with the currently activated instances?
>>     
>
> However, the answer to your question depends on what you mean by
> "highly dynamic cloud environment". If you mean that changes in real
> servers and services will occur from time to time then keepalived
> absolutely supports this.
>
> If you mean that you will be updating the configuration every 3
> seconds, then YMMV. It might work, but you may discover new bugs as
> most people probably don't use keepalived that way.
>
> Also, you have to keep updating/generating the configuration file and
> reloading (no downtime luckily) - there is not CLI or any other
> similar machanism to dynamically update small parts of keepalived conf
> in memory. You would most likely have to do some imaginative scripting.
>
> Siim
>   

The problem is the number of contracting/expanding real servers. 

My suggestion is if there was a mechanism whereby keepalived.conf could 
just import from a database to know the current real servers, something 
like:
/etc/keepalived/servers.d/206.47.60.33:80-192.168.1.2:80.conf
/etc/keepalived/servers.d/206.47.60.33:80-192.168.1.3:80.conf 
/etc/keepalived/servers.d/206.47.60.33:80-192.168.1.4:80.conf 
...

And then in keepalived.conf for virtual server 206.47.60.33 port 80 just 
have something like "import servers.d/206.47.60.33:80-*.conf" or similar.

Now the servers.d/ files could be generated/removed according to current 
active instances and then if the keepalived daemon/server needed 
restarting it would always have the current state for the real servers.

-Gerry





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