apply patch add-xray-response maintained by other RICs

Author: bmoffatt

include/aws/lambda-runtime/runtime.h

@@ -85,6 +85,11 @@ class invocation_response {
      */
     bool m_success;
 
+    /**
+     * The serialized XRay response header.
+     */
+    std::string m_xray_response;
+
     /**
      * Instantiate an empty response. Used by the static functions 'success' and 'failure' to create a populated
      * invocation_response
@@ -97,10 +102,12 @@ class invocation_response {
     // To support clients that need to control the entire error response body (e.g. adding a stack trace), this
     // constructor should be used instead.
     // Note: adding an overload to invocation_response::failure is not feasible since the parameter types are the same.
-    invocation_response(std::string const& payload, std::string const& content_type, bool success)
-        : m_payload(payload), m_content_type(content_type), m_success(success)
-    {
-    }
+    invocation_response(std::string const& payload, std::string const& content_type, bool success, std::string const& xray_response = ""):
+        m_payload(payload),
+        m_content_type(content_type),
+        m_success(success),
+        m_xray_response(xray_response)
+        {}
 
     /**
      * Create a successful invocation response with the given payload and content-type.
@@ -111,7 +118,7 @@ class invocation_response {
      * Create a failure response with the given error message and error type.
      * The content-type is always set to application/json in this case.
      */
-    static invocation_response failure(std::string const& error_message, std::string const& error_type);
+    static invocation_response failure(std::string const& error_message, std::string const& error_type, std::string const& xray_response = "");
 
     /**
      * Get the MIME type of the payload.
@@ -127,6 +134,11 @@ class invocation_response {
      * Returns true if the payload and content-type are set. Returns false if the error message and error types are set.
      */
     bool is_success() const { return m_success; }
+
+    /**
+    * Get the XRay response string. The string isassumed to be UTF-8 encoded.
+    */
+    std::string const& get_xray_response() const { return m_xray_response; }
 };
 
 struct no_result {};

src/runtime.cpp

@@ -347,6 +347,9 @@ runtime::post_outcome runtime::do_post(
         headers = curl_slist_append(headers, ("content-type: " + handler_response.get_content_type()).c_str());
     }
 
+    if (!handler_response.get_xray_response().empty()) {
+        headers = curl_slist_append(headers, ("lambda-runtime-function-xray-error-cause: " + handler_response.get_xray_response()).c_str());
+    }
     headers = curl_slist_append(headers, "Expect:");
     headers = curl_slist_append(headers, "transfer-encoding:");
     headers = curl_slist_append(headers, m_user_agent_header.c_str());
@@ -521,13 +524,14 @@ invocation_response invocation_response::success(std::string payload, std::strin
 }
 
 AWS_LAMBDA_RUNTIME_API
-invocation_response invocation_response::failure(std::string const& error_message, std::string const& error_type)
+invocation_response invocation_response::failure(std::string const& error_message, std::string const& error_type, std::string const& xray_response)
 {
     invocation_response r;
     r.m_success = false;
     r.m_content_type = "application/json";
     r.m_payload = R"({"errorMessage":")" + json_escape(error_message) + R"(","errorType":")" + json_escape(error_type) +
                   R"(","stackTrace":[]})";
+    r.m_xray_response = xray_response;
     return r;
 }