On Thu, Mar 24, 2016 at 07:00:11PM +0100, Willy Tarreau wrote: > Since it's not about > load distribution and that processes are totally independant, I don't see > well how to (ab)use BPF to achieve this. > > The pattern is : > > t0 : unprivileged processes 1 and 2 are listening to the same port > (sock1@pid1) (sock2@pid2) > <------ listening ------> > > t1 : new processes are started to replace the old ones > (sock1@pid1) (sock2@pid2) (sock3@pid3) (sock4@pid4) > <------ listening ------> <------ listening ------> > > t2 : new processes signal the old ones they must stop > (sock1@pid1) (sock2@pid2) (sock3@pid3) (sock4@pid4) > <------- draining ------> <------ listening ------> > > t3 : pids 1 and 2 have finished, they go away > (sock3@pid3) (sock4@pid4) > <------ gone -----> <------ listening ------> >
Thinking a bit more about it, would it make sense to consider that in order to address such a scenario, the only the new (still privileged) process reconfigures the BPF to deliver traffic only to its own sockets and that by doing so it will result in the old one not to receive any of it anymore ? If so that could possibly be reasonably doable then. Ie: the old processes don't have to do anything to stop receiving traffic. Thanks, Willy
