I am running Rails 3.2.3, Ruby 1.9 under Fedora 17. I get this warning, when I run rails s, and how do I fix?
SECURITY WARNING: No secret option provided to Rack::Session::Cookie. This poses a security threat. It is strongly recommended that you provide a secret to prevent exploits that may be possible from crafted cookies. This will not be supported in future versions of Rack, and future versions will even invalidate your existing user cookies.
This is a Rails bug, as the subclass is violating the superclass API contract.
The warning can be safely ignored by Rails users.
(https://github.com/rack/rack/issues/485#issuecomment-11956708, emphasis added)
Confirmation on the rails bug discussion: https://github.com/rails/rails/issues/7372#issuecomment-11981397
Reading the discussion based on tehgeekmeisters answer, this warning is popping up as Rails is using Rack cookies in a different way than intended. It should be ok to just ignore this warning for now until there is a final agreement on how to handle this issue and a fix in place.
This issue has been worked around in the just released Rails 3.2.11.
Log: https://github.com/rails/rails/commits/v3.2.11
Commit: https://github.com/rails/rails/commit/95fe9ef945a35f56fa1c3ef356aec4a3b868937c
rails 3.2.9 - ruby 1.9.3p125 (2012-02-16 revision 34643) [i686-linux]
Hello everyone, the following has worked for me, it may work for you.
/usr/local/lib/ruby/gems/1.9.1/gems/actionpack-3.2.9/lib/action_dispatch/middleware/session/abstract_store.rb
module Compatibility
def initialize(app, options = {})
options[:key] ||= '_session_id'
#fixed warning - SECURITY WARNING: No secret option provided to Rack::Session::Cookie.
options[:secret] ||= Rails.application.config.secret_token
super
end
end
Downgrading to rack 1.4.1 should be sufficient to solve this for now. There's an issue open for this and I just submitted a pull request that seems to fix it for me. In any case, watch the issue, and you should be able to upgrade to rack 1.4.2 after this is fixed.
Apparently, there's ongoing discussion about how to fix this on another issue. You'll have to either downgrade to 1.4.1, ignore it, or figure out your own fix until this is dealt with (and backported, if that even happens).
An issue has been opened in Github https://github.com/rails/rails/issues/8789. It appears that a bug involving Rails 3.2.10 with Rack 1.4.2 is causing this. IMO, it can be safely ignored till the issue is resolved.
EDIT: This issue has been resolved in Rails 3.2.11.
rails update to 3.2.13 ,can solve this question.
Rails users can ignore this message, as it is a Rails bug.
来源：https://stackoverflow.com/questions/10374871/no-secret-option-provided-to-racksessioncookie-warning