On 25/07/2014 07:28 μμ, Willy Tarreau wrote: > Hi all, [..snip..]
> - hot reconfiguration : some users are abusing the reload mechanism to > extreme levels, but that does not void their requirements. And many > other users occasionally need to reload for various reasons such as > adding a new server or backend for a specific customer. While in the > past it was not possible to change a server address on the fly, we > could now do it easily, so we could think about provisionning a few > extra servers that could be configured at run time to avoid a number > of reloads. Concerning the difficulty to bind the reloaded processes, > Simon had done some work in this area 3 years ago with the master- > worker model. Unfortunately we never managed to stabilize it because > of the internal architecture that was hard to adapt and taking a lot > of time. It could be one of the options to reconsider though, along > with FD passing across processes. Similarly, persistent server states > across reloads is often requested and should be explored. > Let's take this to another level and support on-line configuration changes for Frontends, backends and servers which don't require restart and at the same time *dump* the new configuration to haproxy.conf, while on startup haproxy.conf.OK was created. The same way OpenLDAP manages its configuration. This will be very useful in environments where servers register their self to a service(backend in this case) based a health-checks which run locally or by a centralized service. Oh yes, I am talking about Zookeeper integration. In setups where you have N HAProxy servers for serving the same site[1], reducing the number of health-checks is very important. We have been running HAProxy with ~450 backends and ~3000 total servers. The number of health-checks was so high that was causing issues on Firewalls, oh yes we had Firewalls between HAProxy and servers. Once again, we all need to say a big thank you to everyone working on this excellent piece of software. Cheers, Pavlos [1] TCP Anycast setup, where iBGP ECMP balances traffic to N HAProxy servers. Bird runs on HAProxy servers which establishes BGP and BFD sessions to upstream routers, and a service health-check triggers route advertisements if and only if HAProxy runs.
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