10 Most Followed Pugs on Instagram and what they are up to

Introducing Policies

14 min ago 16 comments
By Pugsy Malone

This page demonstrates the how a page structure is made up of standard sized images. Having IO parameters embedded into page markup is a high-risk approach and is subject to inconsistencies across pages.

By using policies, we can simplify the markup by embedding IO rules into VCL.


  table io_policies {
    "article-main": "crop=660:438&width=660",
    "article-large": "crop=318:212&width=318",
    "article-medium": "crop=250:166&width=250",
    "thumb": "crop=80:53&width=80",
    "avatar": "crop=1:1&width=150",
  }


  sub vcl_recv {
  #FASTLY recv

    // Return non-image
    if (req.url.path !~ "(?i)\.(?:jpg|png)$" 
      || req.url.path !~ "/images/") {
      return(lookup);
    }

    // Signal to send to IO
    set req.http.X-Fastly-Imageopto-Api = "fastly";

    // Don't alter the request if we're running at 
    // the shield, it has already been rewritten
    if (req.http.Fastly-FF) {
        return (lookup);
    }
    
    // Policies only
    if (req.url.qs ~ "(?:^|&)policy=([^&]+)") {
      set req.url = req.url.path "?" table.lookup(io_policies, re.group.1, "");
    } else {
      set req.url = req.url.path;
    }

  }
      

                

  //facepug.io/images/a5/pug-instagram.jpg?policy=article-main

  //facepug.io/images/a5/pug-instagram.jpg?policy=article-medium

  //facepug.io/images/a5/pug-instagram.jpg?policy=thumb
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