fix(middleware-serde): add response metadata to deserialization errors (#1588)

* fix(middleware-serde): add response metadata to deserialization errors

* statusCode is number is implied by HttpResponse.isInstance

Author: kuhe

.changeset/tiny-otters-talk.md

@@ -0,0 +1,5 @@
+---
+"@smithy/middleware-serde": patch
+---
+
+add response metadata to deserializer errors

packages/middleware-serde/package.json

@@ -25,6 +25,7 @@
   },
   "license": "Apache-2.0",
   "dependencies": {
+    "@smithy/protocol-http": "workspace:^",
     "@smithy/types": "workspace:^",
     "tslib": "^2.6.2"
   },

packages/middleware-serde/src/deserializerMiddleware.spec.ts

@@ -1,3 +1,4 @@
+import { HttpResponse } from "@smithy/protocol-http";
 import { EndpointBearer, SerdeFunctions } from "@smithy/types";
 import { afterEach, beforeEach, describe, expect, test as it, vi } from "vitest";
 
@@ -39,6 +40,12 @@ describe("deserializerMiddleware", () => {
       statusCode: 200,
       headers: {},
     },
+    $metadata: {
+      httpStatusCode: 200,
+      requestId: undefined,
+      extendedRequestId: undefined,
+      cfId: undefined,
+    },
   };
 
   const mockResponse = {
@@ -139,4 +146,66 @@ describe("deserializerMiddleware", () => {
       expect(e.$response.body).toEqual("oh no");
     }
   });
+
+  describe("metadata", () => {
+    it("assigns metadata from the response in the event of a deserializer failure", async () => {
+      const midware = deserializerMiddleware(mockOptions, async () => {
+        JSON.parse(`this isn't JSON`);
+      });
+      const handler = midware(
+        async () => ({
+          response: new HttpResponse({
+            headers: {
+              "x-namespace-requestid": "requestid",
+              "x-namespace-id-2": "id2",
+              "x-namespace-cf-id": "cf",
+            },
+            statusCode: 503,
+          }),
+        }),
+        {}
+      );
+      try {
+        await handler(mockArgs);
+        fail("DeserializerMiddleware should throw");
+      } catch (e) {
+        expect(e.$metadata).toEqual({
+          httpStatusCode: 503,
+          requestId: "requestid",
+          extendedRequestId: "id2",
+          cfId: "cf",
+        });
+      }
+      expect.assertions(1);
+    });
+
+    it("assigns any available metadata from the response in the event of a deserializer failure", async () => {
+      const midware = deserializerMiddleware(mockOptions, async () => {
+        JSON.parse(`this isn't JSON`);
+      });
+      const handler = midware(
+        async () => ({
+          response: new HttpResponse({
+            statusCode: 301,
+            headers: {
+              "x-namespace-requestid": "requestid",
+            },
+          }),
+        }),
+        {}
+      );
+      try {
+        await handler(mockArgs);
+        fail("DeserializerMiddleware should throw");
+      } catch (e) {
+        expect(e.$metadata).toEqual({
+          httpStatusCode: 301,
+          requestId: "requestid",
+          extendedRequestId: undefined,
+          cfId: undefined,
+        });
+      }
+      expect.assertions(1);
+    });
+  });
 });

packages/middleware-serde/src/deserializerMiddleware.ts

@@ -1,9 +1,11 @@
+import { HttpResponse } from "@smithy/protocol-http";
 import {
   DeserializeHandler,
   DeserializeHandlerArguments,
   DeserializeHandlerOutput,
   DeserializeMiddleware,
   HandlerExecutionContext,
+  MetadataBearer,
   ResponseDeserializer,
   SerdeContext,
   SerdeFunctions,
@@ -60,8 +62,35 @@ export const deserializerMiddleware =
             error.$response.body = error.$responseBodyText;
           }
         }
+
+        try {
+          // if the deserializer failed, then $metadata may still be set
+          // by taking information from the response.
+          if (HttpResponse.isInstance(response)) {
+            const { headers = {} } = response;
+            const headerEntries = Object.entries(headers);
+            (error as MetadataBearer).$metadata = {
+              httpStatusCode: response.statusCode,
+              requestId: findHeader(/^x-[\w-]+-request-?id$/, headerEntries),
+              extendedRequestId: findHeader(/^x-[\w-]+-id-2$/, headerEntries),
+              cfId: findHeader(/^x-[\w-]+-cf-id$/, headerEntries),
+            };
+          }
+        } catch (e) {
+          // ignored, error object was not writable.
+        }
       }
 
       throw error;
     }
   };
+
+/**
+ * @internal
+ * @returns header value where key matches regex.
+ */
+const findHeader = (pattern: RegExp, headers: [string, string][]): string | undefined => {
+  return (headers.find(([k]) => {
+    return k.match(pattern);
+  }) || [void 0, void 1])[1];
+};

yarn.lock

@@ -2791,6 +2791,7 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "@smithy/middleware-serde@workspace:packages/middleware-serde"
   dependencies:
+    "@smithy/protocol-http": "workspace:^"
     "@smithy/types": "workspace:^"
     "@smithy/util-test": "workspace:^"
     concurrently: "npm:7.0.0"