Add prefix header (#62)

* Add prefix header

* rubocop

README.md

@@ -18,3 +18,21 @@ gem 'api_valve'
 
 See the [examples](https://github.com/mkon/api_valve/tree/master/examples) section on how to
 create & configure your own proxy using this gem.
+
+### Headers
+
+By default the following headers are forwarded:
+
+* `Accept`
+* `Content-Type`
+* `User-Agent`
+* `X-Real-IP`
+* `X-Request-Id`
+
+Additionally these headers are generated:
+
+* `X-Forwarded-For`: The ApiGateway is added to the list
+* `X-Forwarded-Host`: Filled with original request host
+* `X-Forwarded-Port`: Filled with original request port
+* `X-Forwarded-Prefix`: Filled with the path prefix of the forwarder within the Api Gateway (eg `SCRIPT_NAME` env)
+* `X-Forwarded-Proto`: Filled with original request scheme

api_valve.gemspec

@@ -3,7 +3,7 @@ $LOAD_PATH.push File.expand_path('lib', __dir__)
 # Describe your gem and declare its dependencies:
 Gem::Specification.new do |s|
   s.name        = 'api_valve'
-  s.version     = ENV.fetch 'VERSION', '0.7.4'
+  s.version     = ENV.fetch 'VERSION', '0.8.0'
   s.authors     = ['mkon']
   s.email       = ['[email protected]']
   s.homepage    = 'https://github.com/mkon/api_valve'

lib/api_valve/forwarder/request.rb

@@ -76,11 +76,12 @@ def permission_handler
 
     def forwarded_headers
       {
-        'X-Forwarded-For'   => x_forwarded_for,
-        'X-Forwarded-Host'  => original_request.host,
-        'X-Forwarded-Port'  => original_request.port.to_s,
-        'X-Forwarded-Proto' => original_request.scheme
-      }
+        'X-Forwarded-For'    => x_forwarded_for,
+        'X-Forwarded-Host'   => original_request.host,
+        'X-Forwarded-Port'   => original_request.port.to_s,
+        'X-Forwarded-Prefix' => original_request.env['SCRIPT_NAME'].presence,
+        'X-Forwarded-Proto'  => original_request.scheme
+      }.compact
     end
 
     def override_path(options)

spec/api_valve/forwarder/request_spec.rb

@@ -16,7 +16,8 @@
       'HTTP_X_FORWARDED_PROTO' => 'https',
       'HTTP_X_REQUEST_ID'      => 'http-x-request-id-123',
       'HTTP_USER_AGENT'        => 'Faraday',
-      'HTTP_OTHER_HEADER'      => 'Ignored'
+      'HTTP_OTHER_HEADER'      => 'Ignored',
+      'SCRIPT_NAME'            => '/some-prefix'
     }
   end
 
@@ -31,12 +32,13 @@
 
     it 'exposes the headers correctly' do # rubocop:disable RSpec/ExampleLength
       expect(headers).to eq(
-        'User-Agent'        => 'Faraday',
-        'X-Forwarded-For'   => '212.122.121.211, 10.0.0.21',
-        'X-Forwarded-Host'  => 'api.example.com',
-        'X-Forwarded-Port'  => '443',
-        'X-Forwarded-Proto' => 'https',
-        'X-Request-Id'      => 'http-x-request-id-123'
+        'User-Agent'         => 'Faraday',
+        'X-Forwarded-For'    => '212.122.121.211, 10.0.0.21',
+        'X-Forwarded-Host'   => 'api.example.com',
+        'X-Forwarded-Port'   => '443',
+        'X-Forwarded-Prefix' => '/some-prefix',
+        'X-Forwarded-Proto'  => 'https',
+        'X-Request-Id'       => 'http-x-request-id-123'
       )
     end
   end