Introduce mounting cascade apps

[ujifgc]

More info at #796

Router will traverse through apps in mount order.
If app mount path matches the request and the app returns 404, router will call next app with matching mount path.
If no apps with matching path return non-404 response, router will return the 404 of the last app.

Update: configure cascade codes: #1471 (comment)

[namusyaka]

Perhaps, rack-protection is the cause of problem.
if change padrino-core.gemspec (>= 1.5.0 to = 1.5.0), it works.

[ujifgc]

Thanks for the tip! I updated the bundle on my machine and got this failure.

So, rack-protection >= 1.5.1 breaks this feature: f1e989f #1391

The last successful Travis build was with rack-protection 1.5.0 https://travis-ci.org/padrino/padrino-framework/jobs/12674078#L274

[namusyaka]

Looks great!

[Ortuna]

Would this cascade to the next app if the first explicitly returns 404? That may not be desired(maybe an edge case). e.g. route is matched in app #1 but 404 is returned.

[ujifgc]

Well, that's how cascading is defined in Rack http://rack.rubyforge.org/doc/classes/Rack/Cascade.html

[Ortuna]

got it, just wondering.

[ujifgc]

I guess, it won't hurt to add configurable status code. On it.

[ujifgc]

You can configure HTTP codes for cascade apps like this:

config/apps.rb:

Padrino.mount("API").to('/foo')
Padrino.mount("Blocker", :cascade => [403]).to('/foo')
Padrino.mount("Application", :cascade => false).to('/foo')
Padrino.mount("LastResort").to('/foo')

In this case the request will pass API on it's 404 and 405 (default pass codes), will pass Blocker on it's 403, won't get to LastResort, it will end on Application.

[dariocravero]

This looks very good @ujifgc 👍! :)

[Ortuna]

👍

[nesquena]

Awesome, nice work @ujifgc. Padrino 0.12.0 is coming along fast with all your guys great contributions. Only 22 open issues. Great work @padrino/core-members!