add https proxy agent

add lib/fetch.js and lib/env.js
replace use of node-fetch in download, scripts and src files

Author: naxmefy

download/src/index.js

@@ -8,10 +8,10 @@ import zlib from 'zlib'
 
 // Packages
 import onDeath from 'death'
-import fetch from 'node-fetch'
 import retry from 'async-retry'
 
 // Utilities
+import fetch from '../../lib/fetch'
 import plusxSync from './chmod'
 import {
   disableProgress,
@@ -21,7 +21,7 @@ import {
   warn
 } from './log'
 
-fetch.Promise = Promise
+fetch.originalFetch.Promise = Promise
 global.Promise = Promise
 let { platform } = process
 if (detectAlpine()) platform = 'alpine'

lib/env.js

@@ -0,0 +1,3 @@
+module.exports = (envString, defaultValue) => {
+    return process.env[envString] || defaultValue
+}

lib/fetch.js

@@ -0,0 +1,16 @@
+const fetch = require('node-fetch')
+const ProxyAgent = require('https-proxy-agent')
+
+const env = require('./env')
+
+const proxy = env('https_proxy') 
+    || env('HTTPS_PROXY')
+    || env('http_proxy')
+    || env('HTTP_PROXY')
+const agent = proxy ? new ProxyAgent(proxy) : undefined
+
+exports = module.exports = (url, options = {}) => {
+    return fetch(url, Object.assign(options, {agent}))
+}
+
+exports.originalFetch = fetch