Nginx gzip Vary header together with existing Vary headers

gzipnginx

I'm trying to active gzip compression and I have set the option gzip_vary on; to include the Vary: Accept-Encoding header.

The problem is, my application is already seting a Vary: header.
So the response is now having two Vary: headers, one from my application and one from nginx.

HTTP/1.1 200 OK
Server: nginx
Date: Sat, 17 Dec 2016 13:28:38 GMT
Content-Type: text/html; charset=UTF-8
Connection: keep-alive
Vary: Accept-Encoding
Last-Modified: Sat, 17 Dec 2016 13:28:38 GMT
Cache-Control: no-cache, no-store, must-revalidate, max-age=0
Pragma: no-cache
Expires: Thu, 01 Jan 1970 00:00:00 GMT
Vary: User-Agent
Content-Encoding: gzip

But I guess instead it should be rather like this:

Vary: Accept-Encoding, User Agent

How can I achieve this?

Best Answer

RFC2616 states duplicate headers are acceptable and should be treated the same as a single header with a comma-separated list of values:

Multiple message-header fields with the same field-name MAY be present in a message if and only if the entire field-value for that header field is defined as a comma-separated list [i.e., #(values)]. It MUST be possible to combine the multiple header fields into one "field-name: field-value" pair, without changing the semantics of the message, by appending each subsequent field-value to the first, each separated by a comma. The order in which header fields with the same field-name are received is therefore significant to the interpretation of the combined field value, and thus a proxy MUST NOT change the order of these field values when a message is forwarded.

So, you don't need to do anything to get the proper behavior.

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