Dynamic real server update without Keepalived reload

[senthilnathann]

Hope doing well.

I need a option to update real server changes dynamically without Keeplaived reload.

Kindly check the possibilities and provide us .

Thanks ,
Senthil.

[pqarmitage]

@senthilnathann Could you please explain why you want to update the configuration without a reload (i.e. what does a reload do that makes it not work for you); reload is provided for updating the configuration and for nothing else.

It would help if you could explain what you want to do in more detail. For example do you want to be able to add and remove various real servers dynamically, but those real servers are known in advance? If that is the case, then we might be able to work something out.

[senthilnathann]

@pqarmitage Thanks for your response .

Yes, we frequently change the real servers and already have the IP details. Applying real server changes directly in IPVS without reloading Keepalived would be helpful for our setup. Therefore, we have raised this request. Please check and do the needful.

[pqarmitage]

If you know all the real servers that you potentially want to be available, then they can all be added to the keepalived configuration file, each with its own FILE_CHECK. To enable a real server, write 0 to the relevant FILE_CHECK file, and to disable a real server, write a non-zero value.

You haven't explained WHY it would be helpful to be able to apply real server changes without doing a configuration update with keepalived, and it would be useful to know in case there is something that we can do to help, not only for you but also for other users.

[senthilnathann]

Purpose :For OS upgrades, we frequently replaced the real server (from old to new), so we thought it was unnecessary to reload every time. Instead, we planned to directly update the IP in memory and modify the IPs in the configuration file, then perform a reload using a scheduler (e.g., once every 12 hours).

Pls help on this .

[pqarmitage]

I am really not sure what it is you are wanting here. A reload is when keepalived re-reads its configuration file, and starts running the new configuration; it doesn't stop operating, and nothing changes state except in relation to the differences in the configuration. So far as I can see this is precisely what you are wanting to do.

If we are to be able to help any further, you will need to describe in detail what doesn't work for you with what I have described above, and, again in detail, what you need to hapen instead.

[senthilnathann]

Thank you for your response. I haven’t encountered any issues with the reload process itself. However, in our setup, real servers are replaced every 10 minutes, which currently requires reloading Keepalived each time. I’m exploring the possibility of dynamically adding real servers without the need for a reload. If this is possible, it would be greatly appreciated and would help reduce the frequency of reloads. If not feasible or requires major changes, please feel free to ignore this request. Thank you again for your support.

[pqarmitage]

Just to be clear, by reload we do NOT mean stopping and restarting keepalived. A reload (triggered by SIGHUP) causes keepalived to re-read the configuration file, and in your case it would remove the real servers no longer in the config and add the real servers that are now in the config but weren't before. So far as I can see, that is precisely what you want.

I guess it would be possible to add an interface to keepalived so that commands could be sent to it to add and remove real servers, virtual servers etc, but that would be a huge change and a very large amount of work, just to achieve something that can already be done.