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= Frequently Asked Questions about \Rainbows!

=== Why is \Rainbows! a separate project from unicorn?

\Rainbows! is for the odd, corner-case requests that unicorn is poorly
suited for.  More scalable concurrency models introduce additional
complexity that unicorn users and developers are uncomfortable with for
the common cases.


=== What complexity?  Threads/events/actors are easy to work with!

Good for you.  Some of us depend on libraries incompatible with those
models, or are just too lazy to deal with them for the majority of
requests we service.


=== Isn't "rainbows" a branch of unicorn?

That functionality is now in the Revactor model of \Rainbows!
However, \Revactor is not recommended since it is dormant
upstream and requires your application (and all its libraries)
to cooperate with \Revactor for concurrency.


=== What happened to the "gossamer" branch of unicorn?

It became the ThreadPool model of \Rainbows!


=== Which concurrency model should I use?

It depends on your application, libraries, Ruby stack and use cases.
That's why we support as many concurrency model as we can.  Each model
has their own strengths and weaknesses in terms of maturity,
ease-of-debugging, compatibility, performance, and memory usage.


=== Should I put \Rainbows! behind nginx to serve slow clients?

It is optional.  You can still use nginx to route certain requests to
unicorn and others to \Rainbows!  nginx will always outperform
\Rainbows! in both pure reverse proxy applications and for serving
static files,  but \Rainbows! is for hosting applications that are more
easily-implemented in Ruby than C.


=== Should I use \Rainbows! to serve static files?

It depends on the size and amount of static files you're serving.  If
you're serving a lot of static files (especially large ones), then by
all means use nginx.  If not, then \Rainbows! is likely a "good enough"
solution even if nginx will always outperform it in raw throughput.


=== How do I support SSL?

If you need streaming "rack.input" to do on-the-fly upload processing
within your Rack application, then using an SSL proxy such as
{Pound}[http://www.apsis.ch/pound/] or {Stunnel}[http://stunnel.org/] is
required.  Pound has built-in X-Forwarded-For support while Stunnel
requires a extra {patch}[http://haproxy.1wt.eu/download/patches/].

If you don't need streaming "rack.input", then nginx is a great HTTPS
reverse proxy.

Refer to the {unicorn FAQ}[https://bogomips.org/unicorn/FAQ.html] on how
to ensure redirects go to "https://" URLs.


=== Is there a "rainbows_rails" command like there is "unicorn_rails"?

No.

"unicorn_rails" was written primarily to support older versions of
Rails.  Since \Rainbows! is designed for newer applications based on
Rack, it can just use a "config.ru" file like other Rack frameworks and
applications.

For Rails 3.x, you should already have a config.ru file and
"rainbows(1)" will work out-of-the-box like "rackup(1)".  Rails 3
will support RACK_ENV as set by "rainbows(1)", so you won't need
to set RAILS_ENV.

For Rails 2.3.x, the following config.ru will work for you:

  ENV["RAILS_ENV"] ||= ENV["RACK_ENV"]
  require "#{::File.expand_path('config/environment')}"
  use Rails::Rack::Static
  run ActionController::Dispatcher.new

For older versions of Rails, the following config.ru will work:

  ENV["RAILS_ENV"] ||= ENV["RACK_ENV"]
  require "#{::File.expand_path('config/boot')}"
  require "#{::File.expand_path('config/environment')}"
  require 'unicorn/app/old_rails'
  require 'unicorn/app/old_rails/static' # not needed with Unicorn 0.95+
  use Unicorn::App::OldRails::Static
  run Unicorn::App::OldRails.new

One thing to watch out for is that RAILS_ENV will not be set in the
environment for you, thus we set it to match RACK_ENV.

=== I'm using threads and Rails is misbehaving!

If you use any of the threaded concurrency models, you will need to use
{config.threadsafe!}[http://m.onkey.org/thread-safety-for-your-rails]
in your config/environments/$RAILS_ENV.rb