X-Cascade header Rack 3 issue

[schinery]

The X-Cascade header in Rack 3 applications appears to need to be lower case, and so it currently doesn't work as expected in Grape apps using Rack 3 using cascade: true.

The following spec, which passes in Rack 2, fails as the default response is returned from Grape instead.

it "raises ActionController::RoutingError" do
  expect { get "/api/foo" }.to raise_error(ActionController::RoutingError)
end

Manually updating my local Grape gem to use x-cascade results in the spec passing again.

[schinery]

Related to #2254

[schinery]

This is what they are doing for Sidekiq Web:

    if Gem::Version.new(Rack::RELEASE) < Gem::Version.new("3")
      CONTENT_LANGUAGE = "Content-Language"
      CONTENT_SECURITY_POLICY = "Content-Security-Policy"
      LOCATION = "Location"
      X_CASCADE = "X-Cascade"
    else
      CONTENT_LANGUAGE = "content-language"
      CONTENT_SECURITY_POLICY = "content-security-policy"
      LOCATION = "location"
      X_CASCADE = "x-cascade"
    end

Would something similar in Grape Headers work?

[dblock]

It would probably work. Start by writing a Rails 6 and 7 spec?

[schinery]

Another option could be to make the X-Cascade and Content-Type (assuming this should also be changed) headers lowercase, as these should work fine in Rack < 3 apps.

Since HTTP/2 requires it and HTTP/1 works fine with it

rack/rack#1592 (comment)

[schinery]

@dblock I've thrown something together for both approaches, please let me know your thoughts and whether either of these is going in the right direction:

• Set response headers based on Rack version #2355
• Lowercase content-type and x-cascade headers #2356

[dblock]

Thanks. Let's dig up why that was changed in Rack before deciding which way to go?

From rack/rack#1592

"I suggest with Rack 3.0 we take the opportunity to enforce the HTTP/2 semantics. It also simplifies the requirements around headers being a hash, to the point where I think it would be acceptable for Rack 3.0."

It feels like we should major-version increment grape if we're going to make a change like this, and lowercase all header names everywhere?

[dblock]

Closed via #2355.