I have tested proxy_cache_key with a single $scheme

 proxy_cache_key $scheme;

Then I request one to cache.


Then I requested again to confirm the cache


No problem

Then I request other url


And hope that it hits cache because the key is $scheme

but it gave me the content of b.html

Why proxy_cache_key $scheme; does not work?

1 Answer 1


The headers from the proxied server response can change the "final" cache key.

From https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_ignore_headers :

If not disabled, processing of these header fields has the following effect:

  • “X-Accel-Expires”, “Expires”, “Cache-Control”, “Set-Cookie”, and “Vary” set the parameters of response caching;

You can check if those headers are included in the response and/or try ignoring them.

  • 1
    I was messing with cookies, and I had a hard time understanding why nginx was still taking into account request "Cookie" (even after ''proxy_set_header Cookie "''). "proxy_ignore_headers Vary" fixed it! Sep 21, 2020 at 11:02

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