How long will google cloud HTTP(S) Load Balancers keep tcp connections open?

Question

tl;dr:

When a google cloud HTTPS load balancer opens a tcp stream (with a "Connection: keep-alive" header in the request), are there any guarantees around how long (at max) that stream will be kept open to the backend server?

longer:

I deployed a Go http server behind an HTTPS load balancer and quickly ran into a lot of issues because I had set an aggressive (10s) read deadline on my socket connections, which meant that my server often closed connections in the middle of reading subsequent requests. So clearly I'm doing that wrong, but at the same time I don't want to not set ANY deadlines on my sockets, because I want to guard against the possibility of these servers slowly leaking dead connections over time, eating up all my file descriptors.

As such, it would be nice if, for example, the load balancers automatically close any tcp streams that they have open after 5 minutes. That way I can set my server's read deadline to (e.g.) 6 minutes and I can be sure that I'll never interrupt any requests - the deadline will only be invoked in exceptional cases (e.g. the FIN packet from the load balancer was not received by my server).

Answer 1

I was unable to get an official answer on this from Google enterprise support, but from my experiments (analyzing multi-hour tcpdumps) it looks like the load balancer will close connections after ~10 minutes of idleness (meaning no tcp data packets for 10 minutes).

Answer 2

Per here, idle TCP connections to Compute Instances are timed out after 10 minutes, which would seem to confirm your hypothesis.