Add echo_request_headers to the test server filter ResponseOptions.

api/server/response_options.proto

@@ -6,7 +6,12 @@ import "google/protobuf/wrappers.proto";
 import "validate/validate.proto";
 import "envoy/api/v2/core/base.proto";
 
+// Options that control the test server response.
 message ResponseOptions {
+  // List of additional response headers.
   repeated envoy.api.v2.core.HeaderValueOption response_headers = 1;
+  // Number of 'a' characters in the the response body.
   uint32 response_body_size = 2 [(validate.rules).uint32 = {lte: 4194304}];
-}
+  // If true, then echo request headers in the response body.
+  bool echo_request_headers = 3;
+}

source/server/README.md

@@ -66,6 +66,62 @@ admin:
       port_value: 8081
 ```
 
+## Response Options config
+
+The ResponseOptions proto can be used in the test-server filter config or passed in `x-nighthawk-test-server-config``
+request header.
+
+The following parameters are available:
+
+* `response_body_size` - number of 'a' characters repeated in the response body.
+* `response_headers` - list of headers to add to response. If `append` is set to
+  `true`, then the header is appended.
+* `echo_request_headers` - if set to `true`, then append the dump of request headers to the response
+  body.
+
+The response options could be used to test and debug proxy or server configuration, for
+example, to verify request headers that are added by intermediate proxy:
+
+```
+$ curl -6 -v [::1]:8080/nighthawk
+
+*   Trying ::1:8080...
+* TCP_NODELAY set
+* Connected to ::1 (::1) port 8080 (#0)
+> GET /nighthawk
+> Host: [::1]:8080
+> User-Agent: curl/7.68.0
+> Accept: */*
+>
+* Mark bundle as not supporting multiuse
+< HTTP/1.1 200 OK
+< content-length: 254
+< content-type: text/plain
+< foo: bar
+< foo: bar2
+< x-nh: 1
+< date: Wed, 03 Jun 2020 13:34:41 GMT
+< server: envoy
+< x-service: nighthawk_cluster
+< via: 1.1 envoy
+<
+aaaaaaaaaa
+Request Headers:
+':authority', '[::1]:8080'
+':path', '/nighthawk'
+':method', 'GET'
+':scheme', 'https'
+'user-agent', 'curl/7.68.0'
+'accept', '*/*'
+'x-forwarded-proto', 'http'
+'via', '1.1 google'
+'x-forwarded-for', '::1,::1'
+* Connection #0 to host ::1 left intact
+```
+
+This example shows that intermediate proxy has added `x-forwarded-proto` and
+`x-forwarded-for` request headers.
+
 ## Running the test server
 
 

source/server/http_test_server_filter.cc

@@ -55,8 +55,12 @@ void HttpTestServerDecoderFilter::applyConfigToResponseHeaders(
 
 void HttpTestServerDecoderFilter::sendReply() {
   if (error_message_ == absl::nullopt) {
+    std::string response_body(base_config_.response_body_size(), 'a');
+    if (request_headers_dump_.has_value()) {
+      response_body += *request_headers_dump_;
+    }
     decoder_callbacks_->sendLocalReply(
-        static_cast<Envoy::Http::Code>(200), std::string(base_config_.response_body_size(), 'a'),
+        static_cast<Envoy::Http::Code>(200), response_body,
         [this](Envoy::Http::ResponseHeaderMap& direct_response_headers) {
           applyConfigToResponseHeaders(direct_response_headers, base_config_);
         },
@@ -78,6 +82,11 @@ HttpTestServerDecoderFilter::decodeHeaders(Envoy::Http::RequestHeaderMap& header
   if (request_config_header) {
     mergeJsonConfig(request_config_header->value().getStringView(), base_config_, error_message_);
   }
+  if (base_config_.echo_request_headers()) {
+    std::stringstream headers_dump;
+    headers_dump << "\nRequest Headers:\n" << headers;
+    request_headers_dump_ = headers_dump.str();
+  }
   if (end_stream) {
     sendReply();
   }

source/server/http_test_server_filter.h

@@ -73,6 +73,7 @@ class HttpTestServerDecoderFilter : public Envoy::Http::StreamDecoderFilter {
   Envoy::Http::StreamDecoderFilterCallbacks* decoder_callbacks_;
   nighthawk::server::ResponseOptions base_config_;
   absl::optional<std::string> error_message_;
+  absl::optional<std::string> request_headers_dump_;
 };
 
 } // namespace Server

test/server/http_test_server_filter_integration_test.cc

@@ -189,6 +189,29 @@ TEST_P(HttpTestServerIntegrationTest, TestHeaderConfig) {
   EXPECT_EQ(std::string(10, 'a'), response->body());
 }
 
+TEST_P(HttpTestServerIntegrationTest, TestEchoHeaders) {
+  for (auto unique_header : {"one", "two", "three"}) {
+    Envoy::BufferingStreamDecoderPtr response = makeSingleRequest(
+        lookupPort("http"), "GET", "/somepath", "", downstream_protocol_, version_, "foo.com", "",
+        [unique_header](Envoy::Http::RequestHeaderMapImpl& request_headers) {
+          request_headers.addCopy(Envoy::Http::LowerCaseString("gray"), "pidgeon");
+          request_headers.addCopy(Envoy::Http::LowerCaseString("red"), "fox");
+          request_headers.addCopy(Envoy::Http::LowerCaseString("unique_header"), unique_header);
+          request_headers.addCopy(
+              Nighthawk::Server::TestServer::HeaderNames::get().TestServerConfig,
+              "{echo_request_headers: true}");
+        });
+    ASSERT_TRUE(response->complete());
+    EXPECT_EQ("200", response->headers().Status()->value().getStringView());
+    EXPECT_THAT(response->body(), HasSubstr(R"(':authority', 'foo.com')"));
+    EXPECT_THAT(response->body(), HasSubstr(R"(':path', '/somepath')"));
+    EXPECT_THAT(response->body(), HasSubstr(R"(':method', 'GET')"));
+    EXPECT_THAT(response->body(), HasSubstr(R"('gray', 'pidgeon')"));
+    EXPECT_THAT(response->body(), HasSubstr(R"('red', 'fox')"));
+    EXPECT_THAT(response->body(), HasSubstr(unique_header));
+  }
+}
+
 class HttpTestServerIntegrationNoConfigTest : public HttpTestServerIntegrationTestBase {
 public:
   void SetUp() override { initialize(); }