Per proxy additional header functionality

README.rdoc

@@ -25,6 +25,12 @@ Below is an example for configuring the middleware:
     # Forward the path /test* to http://example.com/test*
     reverse_proxy '/test', 'http://example.com/'
 
+    # Forward the path /test* to http://example.com/test* with headers
+    reverse_proxy '/test', 'http://example.com/' do
+      add_header 'content-type', 'application/json'
+      add_header 'x-foo-bar', '12345'
+    end
+
     # Forward the path /foo/* to http://example.com/bar/*
     reverse_proxy /^\/foo(\/.*)$/, 'http://example.com/bar$1', :username => 'name', :password => 'basic_auth_secret'
   end

lib/rack/reverse_proxy.rb

@@ -7,9 +7,10 @@ def initialize(app = nil, &b)
       @app = app || lambda {|env| [404, [], []] }
       @matchers = []
       @global_options = {:preserve_host => true, :x_forwarded_host => true, :matching => :all, :verify_ssl => true}
+      @headers = {}
       instance_eval &b if block_given?
     end
-
+    
     def call(env)
       rackreq = Rack::Request.new(env)
       matcher = get_matcher rackreq.fullpath
@@ -18,11 +19,15 @@ def call(env)
       uri = matcher.get_uri(rackreq.fullpath,env)
       all_opts = @global_options.dup.merge(matcher.options)
       headers = Rack::Utils::HeaderHash.new
-      env.each { |key, value|
+
+      env.each do |key, value|
         if key =~ /HTTP_(.*)/
           headers[$1] = value
         end
-      }
+      end
+
+      @headers.each { |key,value| headers[key] = value }
+
       headers['HOST'] = uri.host if all_opts[:preserve_host]
       headers['X-Forwarded-Host'] = rackreq.host if all_opts[:x_forwarded_host]
 
@@ -102,10 +107,15 @@ def reverse_proxy_options(options)
       @global_options=options
     end
 
-    def reverse_proxy matcher, url, opts={}
+    def reverse_proxy matcher, url, opts={}, &block
+      block.yield if block_given?
       raise GenericProxyURI.new(url) if matcher.is_a?(String) && url.is_a?(String) && URI(url).class == URI::Generic
       @matchers << ReverseProxyMatcher.new(matcher,url,opts)
     end
+
+    def add_header name, value
+      @headers[name.to_s] = value.to_s
+    end
   end
 
   class GenericProxyURI < Exception