Change Blindness

My web configuration makes use of Varnish as a front-end, and I noticed a
bug recently where asking for “/study” was failing, while asking for
“/study/” would succeed.

But when I moved Varnish out of the way, Nginx handled this without issue.

So I set out to figure out a recipe for adding the trailing slash within
Varnish. The following solution works for me, but if you know a better way
do let me know.

# If the requested URL contains $directory and doesn’t contain index.php,
add a trailing slash to the end.

sub vcl_recv {
if ((req.url ~ "/directory" ) && (! (req.url ~ "index.php"))){
   set req.url = req.url "/";
}
}

::