Vary: * incorrectly added to http header response (asp.net mvc3)

Question

I am using the following output cache profile:

<add name="MyFunkyProfile" duration="180" varyByParam="*" location="ServerAndClient" />

In dev, I have a response header with one Vary entry:

HTTP/1.1 200 OK
Server: Microsoft-IIS/7.5
...
Vary: Accept-Encoding
Cache-Control: private, max-age=180, s-maxage=0
...

When I deploy my app, I have an extra Vary entry inserted in the response:

HTTP/1.1 200 OK
Server: nginx
...
Vary: Accept-Encoding
Cache-Control: private, max-age=180, s-maxage=0
...
Vary: *
...

Why this extra Vary entry? This is preventing the cache from working correctly.

Any ideas how to fix this?

Jeopardous

Answer 1

Have you tried setting varyByParam to None in your profile/config file? See http://msdn.microsoft.com/en-us/library/hdxfb6cy.aspx.

Also, just guessing here - does the config file differ between dev and 'live', e.g. varyByParam may be set differently?

Note: I've just joined SO so can't add comments just yet (which I would have done instead of posting this as a reply).

Cosette

Can't set varyByParam to None this will yield wrong results. No the varyByParam is set in the same way in dev and prod. The server is different though; dev server vs IIS. – Jeopardous

Answer 2

The Vary: Accept-Encoding header is inserted by the AppHarbor routing layer. The header is necessary to get downstream proxies (typically a CDN like AWS CloudFront or similar) to correctly cache both gzip'ed and non-gzip'ed versions of your content. This question has additional details.

Can you detail how this is causing problems for your application?

Dinger

Vary star is inserted by the framework by default unless varyByParam="" is specified (notice that varyByParam="*" still generates vary star) see Atwood's answer here https://mcmap.net/q/583571/-expire-output-cache-asp-net-mvc . Worked around the problem. Will post the workaround here as answer. – Jeopardous