On Tue, Oct 23, 2012 at 02:27:54AM -0400, Ben Timby wrote: > Willy, > > On Tue, Oct 23, 2012 at 2:10 AM, Willy Tarreau <w...@1wt.eu> wrote: > > Some of us have already been discussing about the possibility to adapt the > > HTTP checks to report a header to modulate the server's weight (in fact it > > was planned for 1.3.14 but skipped because of no use at this time). But we > > can bring this back on the table. > > > > The agent would be very simple in my opinion, it would accept incoming > > connections from the load balancer on a specific port, would check that > > the server is available and will adjust a weight between 0 and 100% > > depending on the number of available connection slots relative to a > > configured max on the servers. > > > > So a server which supports 1000 concurrent connections and runs at 150 > > would have 850/1000 == 85% weight. Then haproxy will still be able to > > use leastconn depending on that weight, to distribute the load across > > all servers. > > > > Does that sound good to you ? > > Yes, that sounds exactly like what I am looking for. > > I suppose if/when this feature hits, I would configure an HTTP check > for each FTP backend (in addition to the port 21 tcp check). The HTTP > check would connect to a simple agent that emitted a header containing > the server's desired weight. HAproxy would handle the rest.
Exactly. > I could get started today by writing a simple poller that would sit on > the load balancer, poll the FTP servers via HTTP and update weights > using the HAProxy control socket. Eventually, HAProxy would handle the > polling via the HTTP check and I could discard the interim poller. Yes, very good idea indeed. And it will help you tune the weight reporting algorithm BTW. Willy
