socket http lua to set timeout - api

Question

I am trying to create a function that can call REST with the http socket lua.
And I tried to set the timeout this way. But, when I run this function, the timeout is not running. How should I set the timeout?
local http = require "socket.http"
local socket = require "socket"
local respbody = {}
http.request {
method = req_method,
url = req_url,
source = ltn12.source.string(req_body),
headers =
{
["Content-Type"] = req_content_type,
["content-length"] = string.len(req_body),
["Host"] = host,
},
sink = ltn12.sink.table(respbody),
create = function()
local req_sock = socket.tcp()
req_sock:settimeout(3, 't')
return req_sock
end,
}

Answer 1

You may want to check lua-http. I use it to call REST and works like a charm. I am not an expert but, as far as I can tell, it is a good LUA http implementation.
You can set a two seconds timeout as simple as:
local http_client = require "http.client"
local myconnection = http_client.connect {
host = "myrestserver.domain.com";
timeout = 2;
}
Full documentation in here.

Answer 2

if I implement the example with my requirements, will it be like this? cmiiw
local http_client = require "http.client"
local req_body = "key1=value1&key2=value2"
local myconnection = http_client.connect {
method = "POST";
url = "myrestserver.domain.com/api/example";
host = "myrestserver.domain.com";
source = req_body
headers = {
["Content-Type"] = "application/x-www-form-urlencoded",
["content-length"] = string.len(req_body),
},
timeout = 2;
}

Answer 3

LuaSocket implicitly set http.TIMEOUT to the socket object.
Also you have to remember that socket timeout is not the same as request timeout.
Socket timeout means timeout for each operation independently. For simple case you can wait connection up to timeout seconds and then each read operation can take up to timeout seconds. And because of HTTP client read response line by line you get timeout seconds for each header plus for each body chunk. Also, there may be redirecions where each redirection is a separate HTTP request/response. If you use TLS there also will be hendshake after connection which also took several send/receive operation.
I did not use lua-http module and do not know how timeout implemented there.
But I prefer use modules like cURL if I really need to restrict request timeout.