title: How to inject custom content via Nginx?
body: <p>Is there a way to inject a few lines of script etc. for each served php/html/etc. page?
  For example some custom javascript after  -tag?</p>
  
  <p>I know, you should be able to use lua in nginx but is there a better solution?</p>
  
  <p>I am running multiple different web application behind the nginx, so it feels proper way to do this. I don't have access source code for each application and maintaining those would be cumbersome.</p>