Add a package for extracting metadata from responses

Author: jeskew

packages/response-metadata-extractor/.gitignore

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+*.js
+*.js.map
+*.d.ts

packages/response-metadata-extractor/__tests__/index.ts

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+import {extractMetadata} from "../index";
+import {HttpResponse} from "@aws/types";
+
+describe('extractMetadata', () => {
+    const response: HttpResponse<string> = {
+        statusCode: 200,
+        headers: {
+            Foo: 'bar',
+            Fizz: 'buzz',
+            Snap: 'crackle, pop',
+        }
+    };
+
+    it('should extract the status code from responses', () => {
+        expect(extractMetadata(response).statusCode).toBe(response.statusCode);
+    });
+
+    it('should extract and downcase headers', () => {
+        expect(extractMetadata(response).responseHeaders).toEqual({
+            foo: response.headers.Foo,
+            fizz: response.headers.Fizz,
+            snap: response.headers.Snap,
+        });
+    });
+
+    it('should extract the request ID from the standard header', () => {
+        expect(extractMetadata({
+            ...response,
+            headers: {
+                'X-Amz-Request-ID': 'id',
+            }
+        }).requestId).toBe('id');
+    });
+
+    it('should extract the request ID from the alternate header', () => {
+        expect(extractMetadata({
+            ...response,
+            headers: {
+                'X-Amz-RequestId': 'id',
+            }
+        }).requestId).toBe('id');
+    });
+
+    it('should prefer the request ID from the standard header', () => {
+        expect(extractMetadata({
+            ...response,
+            headers: {
+                'X-Amz-Request-ID': 'id',
+                'X-Amz-RequestId': 'alt_id',
+            }
+        }).requestId).toBe('id');
+    });
+
+    it('should extract the extended request ID from the standard header', () => {
+        expect(extractMetadata({
+            ...response,
+            headers: {
+                'X-Amz-ID-2': 'extendedId',
+            }
+        }).extendedRequestId).toBe('extendedId');
+    });
+
+    it('should extract the CloudFront ID from the standard header', () => {
+        expect(extractMetadata({
+            ...response,
+            headers: {
+                'X-Amz-CF-ID': 'cfId',
+            }
+        }).cfId).toBe('cfId');
+    });
+});

packages/response-metadata-extractor/index.ts

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+import {
+    HeaderBag,
+    HttpResponse,
+    ResponseMetadata,
+} from "@aws/types";
+
+const REQUEST_ID_HEADER = 'x-amz-request-id';
+const REQUEST_ID_ALT_HEADER = 'x-amz-requestid';
+const EXTENDED_REQUEST_ID_HEADER = 'x-amz-id-2';
+const CF_ID_HEADER = 'x-amz-cf-id';
+
+export function extractMetadata(
+    {headers, statusCode}: HttpResponse<any>
+): ResponseMetadata {
+    const responseHeaders: HeaderBag = Object.keys(headers)
+        .reduce((lowercase: HeaderBag, headerName: string) => {
+            lowercase[headerName.toLowerCase()] = headers[headerName];
+            return lowercase;
+        }, {});
+
+    return {
+        statusCode,
+        responseHeaders,
+        requestId: responseHeaders[REQUEST_ID_HEADER]
+                    || responseHeaders[REQUEST_ID_ALT_HEADER],
+        extendedRequestId: responseHeaders[EXTENDED_REQUEST_ID_HEADER],
+        cfId: responseHeaders[CF_ID_HEADER],
+    };
+}

packages/response-metadata-extractor/package.json

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+{
+  "name": "@aws/response-metadata-extractor",
+  "private": true,
+  "version": "0.0.1",
+  "description": "Provides a function for extracting metadata from responses",
+  "scripts": {
+    "pretest": "tsc",
+    "test": "jest"
+  },
+  "author": "[email protected]",
+  "license": "UNLICENSED",
+  "main": "index.js",
+  "dependencies": {
+    "@aws/types": "^0.0.1"
+  },
+  "devDependencies": {
+    "@types/jest": "^20.0.2",
+    "jest": "^20.0.4",
+    "typescript": "^2.3"
+  }
+}

packages/response-metadata-extractor/tsconfig.json

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+{
+  "compilerOptions": {
+    "target": "es5",
+    "module": "commonjs",
+    "declaration": true,
+    "strict": true,
+    "sourceMap": true
+  }
+}

packages/types/response.ts

@@ -1,11 +1,9 @@
-export interface ResponseHeaders {
-    readonly [index: string]: Array<string>;
-}
+import {HeaderBag} from './http';
 
 export interface ResponseMetadata {
     statusCode: number;
     requestId?: string;
     extendedRequestId?: string;
     cfId?: string;
-    responseHeaders: ResponseHeaders;
+    responseHeaders: HeaderBag;
 }