Add content-lenght to responses and skip when optimization create bigger resource

Author: Szpadel

__tests__/lib/gzip/__snapshots__/middleware.test.js.snap

@@ -10,5 +10,11 @@ Object {
       "value": "gzip",
     },
   ],
+  "content-length": Array [
+    Object {
+      "key": "Content-Length",
+      "value": "0",
+    },
+  ],
 }
 `;

__tests__/lib/gzip/middleware.test.js

@@ -52,6 +52,7 @@ describe('gzip middleware', () => {
         });
 
         expect(response.headers).toEqual({
+            'content-length': [{ key: 'Content-Length', value: '0' }],
             'content-encoding': [{ key: 'Content-Encoding', value: 'gzip' }],
         });
     });

__tests__/lib/imagemin/__snapshots__/middleware.test.js.snap

@@ -4,6 +4,12 @@ exports[`imagemin middleware response body matches snapshot when supported 1`] =
 
 exports[`imagemin middleware response headers match snapshot when supported 1`] = `
 Object {
+  "content-length": Array [
+    Object {
+      "key": "Content-Length",
+      "value": "295787",
+    },
+  ],
   "content-type": Array [
     Object {
       "key": "Content-Type",

__tests__/lib/webp/__snapshots__/middleware.test.js.snap

@@ -4,6 +4,12 @@ exports[`webp middleware response body matches snapshot when supported 1`] = `"/
 
 exports[`webp middleware response headers match snapshot when supported 1`] = `
 Object {
+  "content-length": Array [
+    Object {
+      "key": "Content-Length",
+      "value": "154016",
+    },
+  ],
   "content-type": Array [
     Object {
       "key": "Content-Type",

__tests__/lib/webp/middleware.test.js

@@ -84,6 +84,7 @@ describe('webp middleware', () => {
         });
 
         expect(response.headers).toEqual({
+            'content-length': [{ key: 'Content-Length', value: '154016' }],
             'content-type': [{ key: 'Content-Type', value: 'image/webp' }],
         });
     });

__tests__/origin-request.test.js

@@ -41,23 +41,26 @@ describe('origin-request handler', () => {
         };
         nock('http://example.com')
             .get('/gzip-supported.js')
-            .reply(200, '', { 'content-type': 'text/javascript', 'content-length': '0' });
+            .reply(200, 'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA', { 'content-type': 'text/javascript', 'content-length': '30' });
 
         const callback = jest.fn();
 
         await originRequest.handler(event, null, callback);
 
         expect(callback).toHaveBeenCalledWith(null, {
-            body: 'H4sIAAAAAAACAwMAAAAAAAAAAAA=',
+            body: 'H4sIAAAAAAACA3N0xAcAG2p/MR4AAAA=',
             bodyEncoding: 'base64',
             headers: {
+                'content-length': [
+                    { key: 'Content-Length', value: '23' },
+                ],
                 'content-encoding': [
                     { key: 'Content-Encoding', value: 'gzip' },
                 ],
                 'content-type': [
                     { key: 'Content-Type', value: 'text/javascript' },
                 ],
-                'x-orig-size': [{ key: 'X-Orig-Size', value: '0' }],
+                'x-orig-size': [{ key: 'X-Orig-Size', value: '30' }],
             },
             status: 200,
             statusDescription: 'OK',

lib/gzip/middleware.js

@@ -13,7 +13,9 @@ module.exports = async ({ request, response }) => {
     if (isSupported(request)) {
         const gzipCompress = require('./compress');
 
-        const base64Body = (await gzipCompress(response.body)).toString(
+        const buffer = await gzipCompress(response.body);
+        const contentLength = buffer.byteLength;
+        const base64Body = buffer.toString(
             'base64'
         );
 
@@ -26,6 +28,9 @@ module.exports = async ({ request, response }) => {
                     'content-encoding': [
                         { key: 'Content-Encoding', value: 'gzip' },
                     ],
+                    'content-length': [
+                        { key: 'Content-Length', value: `${contentLength}` },
+                    ],
                 },
             },
             bodyEncoding: 'base64',

lib/imagemin/middleware.js

@@ -9,14 +9,24 @@ module.exports = async ({ request, response }) => {
     if (isSupported(request)) {
         const imageminCompress = require('./compress');
 
-        const base64Body = (await imageminCompress(response.body)).toString(
+        const buffer = await imageminCompress(response.body);
+        const contentLength = buffer.byteLength;
+        const base64Body = buffer.toString(
             'base64'
         );
 
         response = {
             ...response,
             body: base64Body,
             bodyEncoding: 'base64',
+            headers: {
+                ...response.headers,
+                ...{
+                    'content-length': [
+                        { key: 'Content-Length', value: `${contentLength}` },
+                    ],
+                }
+            }
         };
     }
 

lib/limitSize/middleware.js

@@ -1,6 +1,7 @@
 // @ts-check
 
 const logger = require('../logger');
+const { readHeader } = require('../responseHelper');
 
 /**
  * Prevents lambda from throwing 5xx errors because the response it generated exceeds the limit.
@@ -15,6 +16,15 @@ module.exports = async ({ request, response }) => {
             );
             response = request;
         }
+
+        const newContentLength = readHeader(response, 'content-length');
+        const originalContentLength = readHeader(response, 'x-orig-size');
+        if (originalContentLength && newContentLength && newContentLength >= originalContentLength) {
+            logger.log(
+                `Compressed response body size (${newContentLength}B) is not smaller than original size (${originalContentLength}B), skipping.`
+            );
+            response = request;
+        }
     }
 
     return { request, response };

lib/responseHelper.js

@@ -69,8 +69,16 @@ const requestToHeaders = request => {
     return convertedHeaders;
 };
 
+const readHeader = (request, headerName) => {
+    if (request.headers && request.headers[headerName] && request.headers[headerName][0]) {
+        return request.headers[headerName][0].value;
+    }
+    return undefined;
+};
+
 module.exports = {
     isError,
     headersToLambda,
     requestToHeaders,
+    readHeader,
 };