fastcgi_cache_bypass and 502 Bad Gateway

[António P. P. Almeida]

On 11 Fev 2011 16h57 WET, nginx-forum at nginx.us wrote:

> The point I was trying to make is that in this case for instance,
> ...
>
> [code]
> set $donot_cache 0;
> if ($http_cookie ~*
> "comment_author_|wordpress_(?!test_cookie)|wp-postpass_" ) {
> set $donot_cache 1;
> }
> set $test $donot_cache;
> [/code]
>
> ... $test will always be equal to 0 as any variable set within the
> 'if' block is not exposed outside the block AFAIK.
>
> So when you run ...
>
> [code]
> set $donot_cache 0;
> if ($http_cookie ~*
> "comment_author_|wordpress_(?!test_cookie)|wp-postpass_" ) {
> set $donot_cache 1;
> }


This is because as Maxim, and agentzh have explained before: an if is
an *implicit location*. So what you're requesting above is for a
variable with a value changed at a lower level (implicit location) be
visible at an upper level (containing location).

My understanding of Nginx scoping is that it works in one direction,
i.e., you can only be sure that this works global -> http -> server ->
location -> if in location.

There's no reverse path for inheriting variables set at a lower level
on a higher level.

Can someone more knowledgeable than I concur and straighten me if I'm
incorrect?

Thanks,
--- appa

 

 ...
> fastcgi_no_cache   $donot_cache;
> [/code]
>
> ... '$donot_cache' will always resolve to null.
>
> Again, this is AFAIK based on stuff I have read here and there.
>
> See here for instance:
> http://forum.nginx.org/read.php?2,25197,25197#msg-25197
>
> Posted at Nginx Forum:
> http://forum.nginx.org/read.php?2,173795,174192#msg-174192
>
>
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