OpenResty - No response when making a http call with lua

Question

when making a request to an url from within my nginx the response of this request is always not present. It seems that the request is not sended.

This is my nginx.conf

worker_processes  1;
error_log logs/error.log;
events {
    worker_connections 1024;
}

http {
    include       mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for" "$http_clientid"';

    access_log  logs/access.log  main;

    server {
        listen 8080;

        location /token-test {
          access_log logs/token.log main;

          content_by_lua_block {
            local cjson = require "cjson"
            local http = require "resty.http"
            local httpc = http.new()
            local ngx = ngx
            
            local res, err = httpc:request_uri("http://www.google.de", {method="GET"})

            if not res then
               ngx.say(cjson.encode({message = "Error getting response",status = ngx.HTTP_INTERNAL_SERVER_ERROR }))
               return ngx.HTTP_INTERNAL_SERVER_ERROR
            end

            return ngx.HTTP_OK
          }
        }
  }
}

Im getting a 200 response status with this response body:

{
  "status": 500,
  "message": "Error getting response"
}

There are not error in the logs.

Why do I get a 200 response instead of 500 and and why does the response body contain the message from not present condition block?

UPDATE I logged the err: no resolver defined to resolve \"www.google.de\"

Thanks Danny

Answer 1

no resolver defined to resolve "www.google.de"

You need to configure the resolver:

https://github.com/openresty/lua-nginx-module#tcpsockconnect

In case of domain names, this method will use Nginx core's dynamic resolver to parse the domain name without blocking and it is required to configure the resolver directive in the nginx.conf file like this:

resolver 8.8.8.8;  # use Google's public DNS nameserver

---

Why do I get a 200 response instead of 500

You should call ngx.exit to interrupt execution of the request and return the status code.

Replace

return ngx.HTTP_INTERNAL_SERVER_ERROR

with

ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)