a) how do you handle pending shutdown of a load balancer

b) sure ok, if it's an http load balancer, you can finish up the existing requests and any new requests will go to new servers; but if it's a tcp load balancer, those don't generally let you swap the server in the middle

Heh, I guess screw them and shut it down anyway - at least that seems to be the policy in my IT department :)

a) There are several load balancers that allow sharing the state tables. So if you control the network, you share/transfer state tables ahead of removing the LB node from routing. Can even be the same IP with ECMP. I don't know how you would do this on something like an AWS network.

b) In general your right, but this is already a fairly niche use case. But I do wonder if reprogramming the conntrack entry in linux would work, or for lvs which already has a userspace daemon for state synchronization, how it would behave if reprogramming an existing state. It's at least not implausible to do that rewrite somewhere real time... if you control the edge system.

Also, again in a you control the network scenario, OpenFlow switches might allow you to reprogram the state tables while they're live.

netlink has all you need https://github.com/tgraf/libnl/blob/master/src/nf-ct-add.c

The Linux kernel stack is crazy.

For conntrack, one possibility might be to bypass conntrack on incoming connections using `iptables -j NOTRACK`, effectively making the firewall stateless.