Disable Rack::Cache for rails < 4

[teamon]

In Rails prior to 4 when there is set

config.action_controller.perform_caching = true

Rails will automagicly add Rack::Cache middleware to the top of stack. This will cause request with cache headers to be cached which can break e.g. authentication when you want to send cache headers but also always require http basic auth. It is also much better to use nginx or varnish as cache in case auth is not an issue.

For Rails 4 - https://github.com/rails/rails/pull/7838

@jandudulski, @sheerun, @chytreg, @teamon, @szajbus, @Ostrzy, @jcieslar, @tallica

[jandudulski]

Never got this pain, but :+1:

[szajbus]

But you don't always send cache headers, do you?

Not sure if this should be off by default. A guideline for when to use it and when not would be better.

[teamon]

If you do not send cache headers Rack::Cache is noop.

On Friday, 9 August 2013, Michał Szajbe wrote:

But you don't always send cache headers, do you?

Not sure if this should be off by default. A guideline for when to use it and when not would be better.

— Reply to this email directly or view it on GitHubhttps://github.com/monterail/guidelines/issues/176#issuecomment-22361494 .

[szajbus]

I meant that for some request you want to send it and for others not.

[teamon]

1. Rack::Cache on + sending cache headers = pain
2. Rack::Cache on + not sending cache headers = doesn't matter (Rack::Cache is transparent)
3. Rack::Cache off + sending cache headers = profit
4. Rack::Cache off + not sending cache headers = doesn't matter (Rack::Cache is transparent)

[jandudulski]

So.. what is the purpose of this Rack::Cache?

[teamon]

1. Rack::Cache on + sending cache headers + auth = pain
2. Rack::Cache on + sending cache headers + no auth = ok
3. Rack::Cache on + not sending cache headers + auth = doesn't matter (Rack::Cache is transparent)
4. Rack::Cache on + not sending cache headers + no auth = doesn't matter (Rack::Cache is transparent)
5. Rack::Cache off + sending cache headers + auth = ok
6. Rack::Cache off + sending cache headers + no auth = ok
7. Rack::Cache off + not sending cache headers + auth = doesn't matter (Rack::Cache is transparent)
8. Rack::Cache off + not sending cache headers + no auth = doesn't matter (Rack::Cache is transparent)

[jandudulski]

Wait... so whether you use or not Rack::Cache you will cache when cache headers were sent?

[teamon]

Rack::Cache will only cache if it is enabled

[sheerun]

we have 3 ok and only one pain ;) why you send cache headers on auth?

On Fri, Aug 9, 2013 at 11:59 AM, Tymon Tobolski notifications@github.comwrote:

Rack::Cache will only cache in it is on

— Reply to this email directly or view it on GitHubhttps://github.com/monterail/guidelines/issues/176#issuecomment-22385581 .

[teamon]

I want to cache api secured with basic auth.

[chytreg]

@teamon What about this guideline https://github.com/monterail/guidelines/blob/master/rails.md#rack-cache should we modify it in prior of disable rack cache?

[sheerun]

@szajbus What's the decision?

[teamon]

@chytreg There are the correct settings if you do use rack cache, but the general guideline will be to disable it completely.

[szajbus]

I am still not convinced. If does cause pain in some situations why not disable cache only for them by sending appropriate headers. By default all non-GET requests should not be cached I guess.

I understand your use case. Requests with Basic Auth headers indeed will not play well here. But maybe a better solution would be to set appropriate headers for such requests.

http://stackoverflow.com/questions/49547/making-sure-a-web-page-is-not-cached-across-all-browsers/2068407#2068407

[teamon]

My use case is strictly http API. I do want to have internal server side cache, basic authentication and client side cache using ETag, Cache-Control and Last-Modified. Rack::Cache is just put in wrong place, before authentication. And it is disabled completely in rails 4 which I'd take as a suggestion not to use it at all.

Tymon Tobolski Monterail.com (http://Monterail.com) – Ruby on Rails development agency

On Wednesday, September 18, 2013 at 12:33 AM, Michał Szajbe wrote:

I am still not convinced. If does cause pain in some situations why not disable cache only for them by sending appropriate headers. By default all non-GET requests should not be cached I guess. I understand your use case. Requests with Basic Auth headers indeed will not play well here. But maybe a better solution would be to set appropriate headers for such requests. http://stackoverflow.com/questions/49547/making-sure-a-web-page-is-not-cached-across-all-browsers/2068407#2068407

— Reply to this email directly or view it on GitHub (https://github.com/monterail/guidelines/issues/176#issuecomment-24628047).

[szajbus]

Even when it is before authentication it would not cache its responses if the responses set appropriate headers from the start, right? Or I still don't see something.

Rails4 is a very good hint though! So I lean towards :+1:

[teamon]

If response have no headers rack::cache will not cache it, nor will client ;]

[charlesdeb]

Hi folks, this will also disable Rack::Cache in your app apparently:

config.action_dispatch.rack_cache =  nil

from the bottom of this page: http://blog.tonycode.com/archives/418