Openresty log_by_lua_block non blocking http-request

Question

In one of nginx locations I have log_by_lua_block, where I need to send several ngx.var variables to remote server over http. If I use something like Lua-cURL it block nginx worker until the request is completed. What is the correct way to send non blocking http-request from log_by_lua_block?

Something like:

location / {
   proxy_pass http://host;

   log_by_lua_block {  
          someAsyncCurlRequest(ngx.var)
   }    
}

Answer 1

I did so:

location /proxy/ { 
    rewrite /proxy/(.*) /$1  break; 
    allow 127.0.0.1; 
    deny all; 
    proxy_pass $1; 
}

log_by_lua_block {  
    local cjson = require "cjson.safe"
    local postData = {}
    postData["userIP"] = $remote_addr
    res = ngx.location.capture_multi{{"/proxy/http://urlPath",{ method = ngx.HTTP_POST, body = cjson.encode(postData)}},}
}