feat: use custom url for binary download

Author: n1ru4l

README.md

@@ -399,6 +399,9 @@ Youtube-dl looks for certain environment variables to aid its operations. If You
 
 - **YOUTUBE\_DL\_DOWNLOAD\_HOST** - overwrite URL prefix that is used to download the binary file of Youtube-dl. Note: this includes protocol and might even include path prefix. Defaults to `https://yt-dl.org/downloads/latest/youtube-dl`.
 
+- **YOUTUBE_DL_DIRECT_BINARY_DOWNLOAD_URL** - download the youtube-dl binary from the given download url, completely ignoring the `**YOUTUBE\_DL\_DOWNLOAD\_HOST**` option, while performing no lookup for retrieving the latest version of the binary. This is useful if you are hosting the youtube-dl binary on your own S3 bucket. The platform specific extension will be appended.
+E.g. the value `https://xxxxx.s3.xxxxxx.amazonaws.com/2020.11.12-youtube-dl` will result in downloading `https://xxxxx.s3.xxxxxx.amazonaws.com/2020.11.12-youtube-dl.exe` on windows.
+
 ### Tests
 
 Tests are written with [vows](http://vowsjs.org/)

lib/downloader.js

@@ -6,6 +6,9 @@ const path = require('path')
 const util = require('util')
 const fs = require('fs')
 
+const DIRECT_BINARY_DOWNLOAD_URL =
+  process.env.YOUTUBE_DL_DIRECT_BINARY_DOWNLOAD_URL
+
 const ENDPOINT =
   process.env.YOUTUBE_DL_DOWNLOAD_HOST ||
   'https://youtube-dl-binary.vercel.app/'
@@ -72,7 +75,7 @@ function downloader (binDir, callback) {
 
   createBase(binDir)
 
-  // handle overwritin
+  // handle overwriting
   if (fs.existsSync(filePath)) {
     if (!isOverwrite) {
       return callback('File exists')
@@ -85,6 +88,30 @@ function downloader (binDir, callback) {
     }
   }
 
+  if (DIRECT_BINARY_DOWNLOAD_URL !== undefined) {
+    const binaryUrl = DIRECT_BINARY_DOWNLOAD_URL + isWin ? '.exe' : ''
+
+    const downloadFile = request.get(binaryUrl)
+    const outputStream = fs.createWriteStream(filePath, { mode: 493 })
+    outputStream.on('close', function end () {
+      callback(null, 'Downloaded youtube-dl from custom mirror.')
+      fs.writeFileSync(
+        defaultPath,
+        JSON.stringify({
+          version: 'custom-mirror-version',
+          path: binDir ? filePath : binDir,
+          exec: exec('youtube-dl')
+        }),
+        'utf8'
+      )
+    })
+    downloadFile.pipe(outputStream)
+    downloadFile.on('error', function error (err) {
+      callback(err)
+    })
+    return
+  }
+
   download(
     `${ENDPOINT}?platform=${isWin ? 'windows' : 'linux'}`,
     function error (err, newVersion) {