On Tue, Jun 2, 2009 at 3:32 PM, Willy Tarreau <w...@1wt.eu> wrote: > Hi Ryan, > > On Mon, Jun 01, 2009 at 12:22:57PM -0700, Ryan Schlesinger wrote: > > I've got haproxy set up (with 2 frontends) to load balance a php app > > which works great. However, we're using a java uploader applet that > > doesn't appear to handle cookies. It would be simple for me to have the > > uploader use a URL with the server id in it (just like we're already > > doing with the session id) but I don't see any way to get haproxy to > > treat that parameter as the actual server id. Using hashing is not an > > option as changing the number of running application servers is a normal > > occurrence for us. I also can't use the appsession directive as the > > haproxy session id cache isn't shared between the two frontends (both > > running an instance of haproxy). Can this be done with ACLs and I'm > > missing it? >
I actually made a patch for a client the last time that does this exact thing. I'll see if this client is ok with sharing the code - or opensourcing it. Willy's approach is also an interesting way of doing it - you control the decision of what to do if the backend is down using the acl 'srv(1|2)_up'.... -jf > You could very well use ACLs to match your URL parameter in the > frontend and switch to either backend 1 or backend 2 depending > on the value. > > Alternatively, you could hash the URL parameter (balance url_param) > but it would not necessarily be easy for your application to generate > an URL param which will hash back to the same server. So I think that > the ACL method is the most appropriate for your case. > > Basically you'd do that : > > frontend > acl srv1 url_sub SERVERID=1 > acl srv2 url_sub SERVERID=2 > acl srv1_up nbsrv(bck1) gt 0 > acl srv2_up nbsrv(bck2) gt 0 > use_backend bck1 if srv1_up srv1 > use_backend bck2 if srv2_up srv2 > default_backend bck_lb > > backend bck_lb > # Perform load-balancing. Servers state is tracked > # from other backends. > balance roundrobin > server srv1 1.1.1.1 track bck1/srv1 > server srv2 1.1.1.2 track bck2/srv2 > ... > > backend bck1 > balance roundrobin > server srv1 1.1.1.1 check > > backend bck2 > balance roundrobin > server srv2 1.1.1.2 check > > That's just a guideline, but I think you should manage to get > it working based on that. > > Regards, > Willy > > >
