I've got dozens of clients connecting with Stunnel to a group of 5 servers. Each system has a config that looks like this:
cert = /etc/stunnel/zookeeper.pem key = /etc/stunnel/zookeeper.key CAfile = /etc/stunnel/zookeeper_ca.pem verify = 2 delay = yes sslVersion = TLSv1 client = yes setuid = stunnel4 setgid = stunnel4 pid = /var/lib/stunnel4/zookeeper.stunnel4.pid socket = l:TCP_NODELAY=1 socket = r:TCP_NODELAY=1 TIMEOUTconnect = 2 session = 86400 debug = 5 [zookeeper] accept = 127.0.0.1:2182 failover = rr connect = prod-zookeeper:2182 connect = prod-zookeeper-1:2182 connect = prod-zookeeper-2:2182 connect = prod-zookeeper-3:2182 connect = prod-zookeeper-4:2182 connect = prod-zookeeper-5:2182
Essentially the first host is a load balancer, and the next 5 are the actual zookeeper hosts so that we can bypass the ELB if its giving us fits. Now what we're seeing is that almost every connection ends up on prod-zookeeper-5. Over and over and over again, our hosts pick the same system each time. We're running Stunnel 4.52:
Clients allowed=8000 stunnel 4.52 on i486-pc-linux-gnu platform Compiled/running with OpenSSL 0.9.8k 25 Mar 2009 Threading:PTHREAD SSL:ENGINE Auth:LIBWRAP Sockets:POLL,IPv6
Any ideas what might be wrong here? Obviously we want the connections to be *roughly* random across the list of hosts... and if one of the hosts goes down, and the connection fails, we want the stunnel service to try again, and randomly pick a new host. It doesn't really seem to be doing that though.
--Matt