nginx upstream $http variable (exists) checking

Roland

11/15/23, 8:44 AM

Want to use proxy cache on selected pages, for these I've added a header variable ngx_cachekey. Other pages that is not for caching are don't have this header variable.

mysite.com/cacheable-page (has the ngx_cachekey in the header) mysite.com/dynamic-content (has no the ngx_cachekey in the header)

I can debug this with add_header X-NGX-CacheKey $upstream_http_ngx_cachekey; , so setting the variable and giving to the nginx is working.

But i'm unable to check if the $upstream_http_ngx_cachekey exists in IF statement.

    location / {
      set $cacheByPass 1;
      if ($upstream_http_ngx_cachekey) {
        set $cacheByPass 0;
      }

the $cacheByPass always returns 1 even if the $upstream_http_ngx_cachekey has value. I'm looking for a solution similar to PHP isset() if there's any.

Thank you in advance!

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