Support compression based on accept-encoding header

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.split(',').map(str => str.trim()))
+
+  // Handle Brotli compression
+  if (acceptableEncodings.has('br')) {
+    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 +469,16 @@ 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) {
+        this._isBase64 = true
+        this._response.body = data.toString('base64')
+        this._response.headers['content-encoding'] = [contentEncoding]
+      }
+    }
+
     // Trigger the callback function
     this.app._callback(null, this._response, this)