Support default_middleware configuration option

This allows for the equivalent of the
-N/--no-default_middleware command line option to be
specified in the configuration file so it doesn't
need to be specified on the command line every time
unicorn is executed.

It explicitly excludes the use of -N/--no-default_middleware
as an embedded configuration option in the rackup file, by
ignoring the options after ARGV is parsed.

In order to allow the configuration method to work, have
the lambda that Unicorn.builder returns accept two arguments.
Technically, only one argument is needed for the HttpServer
instance, but I'm guessing if the lambda accepts a single
argument, we expect that to be a rack application instead
of a lambda that returns a rack application.

The command line option option to disable default middleware
will take precedence over the unicorn configuration file option
if both are present.

For backwards compatibility, if the lambda passed to
HttpServer accepts 0 arguments, then call it without
arguments.

[ew: fix precedence for arity checking in build_app!
     configurator: ensure -N is respected when set in command-line]

Author: jeremyevans

bin/unicorn

@@ -6,6 +6,7 @@ require 'optparse'
 ENV["RACK_ENV"] ||= "development"
 rackup_opts = Unicorn::Configurator::RACKUP
 options = rackup_opts[:options]
+set_no_default_middleware = true
 
 op = OptionParser.new("", 24, '  ') do |opts|
   cmd = File.basename($0)
@@ -60,7 +61,7 @@ op = OptionParser.new("", 24, '  ') do |opts|
 
   opts.on("-N", "--no-default-middleware",
           "do not load middleware implied by RACK_ENV") do |e|
-    rackup_opts[:no_default_middleware] = true
+    rackup_opts[:no_default_middleware] = true if set_no_default_middleware
   end
 
   opts.on("-D", "--daemonize", "run daemonized in the background") do |d|
@@ -110,6 +111,7 @@ op = OptionParser.new("", 24, '  ') do |opts|
   opts.parse! ARGV
 end
 
+set_no_default_middleware = false
 app = Unicorn.builder(ARGV[0] || 'config.ru', op)
 op = nil
 

lib/unicorn.rb

@@ -45,12 +45,8 @@ def self.builder(ru, op)
       abort "rack and Rack::Builder must be available for processing #{ru}"
     end
 
-    # Op is going to get cleared before the returned lambda is called, so
-    # save this value so that it's still there when we need it:
-    no_default_middleware = op[:no_default_middleware]
-
     # always called after config file parsing, may be called after forking
-    lambda do ||
+    lambda do |_, server|
       inner_app = case ru
       when /\.ru$/
         raw = File.read(ru)
@@ -66,7 +62,7 @@ def self.builder(ru, op)
         pp({ :inner_app => inner_app })
       end
 
-      return inner_app if no_default_middleware
+      return inner_app unless server.default_middleware
 
       middleware = { # order matters
         ContentLength: nil,

lib/unicorn/configurator.rb

@@ -88,6 +88,9 @@ def reload(merge_defaults = true) #:nodoc:
     RACKUP[:set_listener] and
       set[:listeners] << "#{RACKUP[:host]}:#{RACKUP[:port]}"
 
+    RACKUP[:no_default_middleware] and
+      set[:default_middleware] = false
+
     # unicorn_rails creates dirs here after working_directory is bound
     after_reload.call if after_reload
 
@@ -265,6 +268,14 @@ def worker_processes(nr)
     set_int(:worker_processes, nr, 1)
   end
 
+  # sets whether to add default middleware in the development and
+  # deployment RACK_ENVs.
+  #
+  # default_middleware is only available in unicorn 5.5.0+
+  def default_middleware(bool)
+    set_bool(:default_middleware, bool)
+  end
+
   # sets listeners to the given +addresses+, replacing or augmenting the
   # current set.  This is for the global listener pool shared by all
   # worker processes.  For per-worker listeners, see the after_fork example

lib/unicorn/http_server.rb

@@ -14,7 +14,8 @@ class Unicorn::HttpServer
   attr_accessor :app, :timeout, :worker_processes,
                 :before_fork, :after_fork, :before_exec,
                 :listener_opts, :preload_app,
-                :orig_app, :config, :ready_pipe, :user
+                :orig_app, :config, :ready_pipe, :user,
+                :default_middleware
   attr_writer   :after_worker_exit, :after_worker_ready, :worker_exec
 
   attr_reader :pid, :logger
@@ -70,6 +71,7 @@ def initialize(app, options = {})
     @app = app
     @request = Unicorn::HttpRequest.new
     @reexec_pid = 0
+    @default_middleware = true
     options = options.dup
     @ready_pipe = options.delete(:ready_pipe)
     @init_listeners = options[:listeners] ? options[:listeners].dup : []
@@ -784,12 +786,12 @@ def listener_names(listeners = LISTENERS)
   end
 
   def build_app!
-    if app.respond_to?(:arity) && app.arity == 0
+    if app.respond_to?(:arity) && (app.arity == 0 || app.arity == 2)
       if defined?(Gem) && Gem.respond_to?(:refresh)
         logger.info "Refreshing Gem list"
         Gem.refresh
       end
-      self.app = app.call
+      self.app = app.arity == 0 ? app.call : app.call(nil, self)
     end
   end