Automatic Compression

README.md

@@ -1342,7 +1342,17 @@ You can also use the `cors()` ([see here](#corsoptions)) convenience method to a
 Conditional route support could be added via middleware or with conditional logic within the `OPTIONS` route.
 
 ## Compression
-Currently, API Gateway HTTP APIs do not support automatic compression out of the box, but that doesn't mean the Lambda can't return a compressed response. In order to create a compressed response instantiate the API with `isBase64` set to true, and a custom serializer that returns a compressed response as a base64 encoded string. Also, don't forget to set the correct `content-encoding` header:
+Currently, API Gateway HTTP APIs do not support automatic compression, but that doesn't mean the Lambda can't return a compressed response. Lambda API supports compression out of the box:
+
+```javascript
+const api = require('lambda-api')({
+  compression: true
+})
+```
+
+The response will automatically be compressed based on the `Accept-Encoding` header in the request. Supported compressions are Brotli, Gzip and Deflate - in that priority order.
+
+For full control over the response compression, instantiate the API with `isBase64` set to true, and a custom serializer that returns a compressed response as a base64 encoded string. Also, don't forget to set the correct `content-encoding` header:
 
 ```javascript
 const zlib = require('zlib')

index.d.ts

@@ -103,6 +103,7 @@ export declare interface Options {
   version?: string;
   errorHeaderWhitelist?: string[];
   isBase64?: boolean;
+  compression?: boolean;
   headers?: object;
 }
 

index.js

@@ -29,6 +29,7 @@ class API {
     this._errorHeaderWhitelist = props && Array.isArray(props.errorHeaderWhitelist) ? props.errorHeaderWhitelist.map(header => header.toLowerCase()) : []
     this._isBase64 = props && typeof props.isBase64 === 'boolean' ? props.isBase64 : false
     this._headers = props && props.headers && typeof props.headers === 'object' ? props.headers : {}
+    this._compression = props && typeof props.compression === 'boolean' ? props.compression : false
 
     // Set sampling info
     this._sampleCounts = {}

lib/compression.js

@@ -0,0 +1,43 @@
+'use strict'
+
+/**
+ * Lightweight web framework for your serverless applications
+ * @author Jeremy Daly <jeremy@jeremydaly.com>
+ * @license MIT
+*/
+
+const zlib = require('zlib')
+
+exports.compress = (input,headers) => {
+  const acceptEncodingHeader = headers['accept-encoding'] || ''
+  const acceptableEncodings = new Set(acceptEncodingHeader.toLowerCase().split(',').map(str => str.trim()))
+
+  // Handle Brotli compression (Only supported in Node v10 and later)
+  if (acceptableEncodings.has('br') && typeof zlib.brotliCompressSync === 'function') {
+    return {
+      data: zlib.brotliCompressSync(input),
+      contentEncoding: 'br'
+    }
+  }
+
+  // Handle Gzip compression
+  if (acceptableEncodings.has('gzip')) {
+    return {
+      data: zlib.gzipSync(input),
+      contentEncoding: 'gzip'
+    }
+  }
+
+  // Handle deflate compression
+  if (acceptableEncodings.has('deflate')) {
+    return {
+      data: zlib.deflateSync(input),
+      contentEncoding: 'deflate'
+    }
+  }
+
+  return {
+    data: input,
+    contentEncoding: null
+  }
+}

lib/response.js

@@ -10,6 +10,7 @@ const UTILS = require('./utils.js')
 
 const fs = require('fs') // Require Node.js file system
 const path = require('path') // Require Node.js path
+const compression = require('./compression') // Require compression lib
 const { ResponseError, FileError } = require('./errors') // Require custom errors
 
 // Require AWS S3 service
@@ -47,6 +48,9 @@ class RESPONSE {
     // base64 encoding flag
     this._isBase64 = app._isBase64
 
+    // compression flag
+    this._compression = app._compression
+
     // Default callback function
     this._callback = 'callback'
 
@@ -465,6 +469,19 @@ class RESPONSE {
       this._request.interface === 'alb' ? { statusDescription:  `${this._statusCode} ${UTILS.statusLookup(this._statusCode)}` } : {}
     )
 
+    // Compress the body
+    if (this._compression && this._response.body) {
+      const { data, contentEncoding } = compression.compress(this._response.body, this._request.headers)
+      if (contentEncoding) {
+        Object.assign(this._response, { body: data.toString('base64'), isBase64Encoded: true })
+        if (this._response.multiValueHeaders) {
+          this._response.multiValueHeaders['content-encoding'] = [contentEncoding]
+        } else {
+          this._response.headers['content-encoding'] = contentEncoding
+        }
+      }
+    }
+
     // Trigger the callback function
     this.app._callback(null, this._response, this)
 

test/responses.js

@@ -27,12 +27,18 @@ const api4 = require('../index')({
     return gzipSync(json).toString('base64')
   }
 })
+// Init API with compression
+const api5 = require('../index')({
+  version: 'v1.0',
+  compression: true
+})
 
 let event = {
   httpMethod: 'get',
   path: '/test',
   body: {},
   multiValueHeaders: {
+    'Accept-Encoding': ['deflate, gzip'],
     'Content-Type': ['application/json']
   }
 }
@@ -123,6 +129,10 @@ api4.get('/testGZIP', function(req,res) {
   res.json({ object: true })
 })
 
+api5.get('/testGZIP', function(req,res) {
+  res.json({ object: true })
+})
+
 /******************************************************************************/
 /***  BEGIN TESTS                                                           ***/
 /******************************************************************************/
@@ -278,6 +288,12 @@ describe('Response Tests:', function() {
     expect(result).to.deep.equal({ multiValueHeaders: { 'content-encoding': ['gzip'], 'content-type': ['application/json'] }, statusCode: 200, body: 'H4sIAAAAAAAAE6tWyk/KSk0uUbIqKSpN1VGKTy4tLsnPhXOTEotTzUwg3FoAan86iy0AAAA=', isBase64Encoded: true })
   }) // end it
 
+  it('Compression (GZIP)', async function() {
+    let _event = Object.assign({},event,{ path: '/testGZIP'})
+    let result = await new Promise(r => api5.run(_event,{},(e,res) => { r(res) }))
+    expect(result).to.deep.equal({ multiValueHeaders: { 'content-encoding': ['gzip'], 'content-type': ['application/json'] }, statusCode: 200, body: 'H4sIAAAAAAAAE6tWyk/KSk0uUbIqKSpNrQUAAQd5Ug8AAAA=', isBase64Encoded: true })
+  }) // end it
+
   after(function() {
     stub.restore()
   })