Question

Looks like setting timeout for Lua socket only works after connect, and I can’t use assert (socket.connect (..)), because I have multiple servers to try out.

My scenario is that when one server is down (can’t connect rather than unstable network), I will resort to a different one, so I must have a timeout on connect.

Any suggestions?

EDIT

I found Lua TCP socket, but with that, I was unable to detect connection failure,

local tcp = socket.tcp()
tcp:settimeout(1)
tcp:connect(...)

Answer 1

If it does not work it is probably because your luasocket is too old, update to version 2:

Starting with LuaSocket 2.0, the settimeout method affects the behavior of connect, causing it to return with an error in case of a timeout.

(source: http://w3.impa.br/~diego/software/luasocket/tcp.html#connect)