Load balancing with "content_by_lua block"

[Fatahir]

I have a content_by_lua block which execute when below location run.

location / {
      content_by_lua '
          local client = require "readuser"
          client.ReadUser();
      ';
    }

I want to do load balancing between multiple servers so that all servers run same lua block. I thought i did this by

http
{
 upstream read
 {
  server one;
  server two;
  server three;
 }
}

server {
 location / {
  proxy_pass http://read
  content_by_lua '
          local client = require "readuser"
          client.ReadUser();
      ';
 }
}

but it did not work. How can I achieved this with lua block?