title: How can I upload an FTP file to firebase storage using Cloud Functions for Firebase?
body: <p>Within the same firebase project and using a cloud function (written in node.js), I first download an FTP file (using npm ftp module) and then try to upload it into the firebase storage.</p>
  
  <p>Every attempts failed so far and documentation doesn't help...any expert advices/tips would be greatly appreciated?</p>
  
  <p>The following code uses two different approaches : fs.createWriteStream() and bucket.file().createWriteStream(). Both failed but for different reasons (see error messages in the code).</p>
  
  <pre><code>'use strict'
  
  // [START import]
  let admin = require('firebase-admin')
  let functions = require('firebase-functions')
  const gcpStorage = require('@google-cloud/storage')()
  admin.initializeApp(functions.config().firebase)    
  var FtpClient = require('ftp')
  var fs = require('fs')
  // [END import]
  
  // [START Configs]
  // Firebase Storage is configured with the following rules and grants read write access to everyone
  /*
  service firebase.storage {
    match /b/{bucket}/o {
      match /{allPaths=**} {
        allow read, write;
      }
    }
  }
  */
  // Replace this with your project id, will be use by: const bucket = gcpStorage.bucket(firebaseProjectID)
  const firebaseProjectID = 'your_project_id'
  // Public FTP server, uploaded files are removed after 48 hours ! Upload new ones when needed for testing
  const CONFIG = {
    test_ftp: {
      source_path: '/48_hour',
      ftp: {
        host: 'ftp.uconn.edu'
      }
    }
  }
  const SOURCE_FTP  = CONFIG.test_ftp
  // [END Configs]
  
  // [START saveFTPFileWithFSCreateWriteStream]
  function saveFTPFileWithFSCreateWriteStream(file_name) {
    const ftpSource = new FtpClient()
    ftpSource.on('ready', function() {
      ftpSource.get(SOURCE_FTP.source_path + '/' + file_name, function(err, stream) {
        if (err) throw err
        stream.once('close', function() { ftpSource.end() })
        stream.pipe(fs.createWriteStream(file_name))
        console.log('File downloaded: ', file_name)
      })
    })
    ftpSource.connect(SOURCE_FTP.ftp)
  }
  // This fails with the following error in firebase console:
  // Error: EROFS: read-only file system, open '20170601.tar.gz' at Error (native)
  // [END saveFTPFileWithFSCreateWriteStream]
  
  // [START saveFTPFileWithBucketUpload]    
  function saveFTPFileWithBucketUpload(file_name) {
    const bucket = gcpStorage.bucket(firebaseProjectID)
    const file = bucket.file(file_name)
    const ftpSource = new FtpClient()
    ftpSource.on('ready', function() {
      ftpSource.get(SOURCE_FTP.source_path + '/' + file_name, function(err, stream) {
        if (err) throw err
        stream.once('close', function() { ftpSource.end() })
        stream.pipe(file.createWriteStream())
        console.log('File downloaded: ', file_name)
      })
    })
    ftpSource.connect(SOURCE_FTP.ftp)
  }    
  // [END saveFTPFileWithBucketUpload]
  
  // [START database triggers]
  // Listens for new triggers added to /ftp_fs_triggers/:pushId and calls the saveFTPFileWithFSCreateWriteStream
  // function to save the file in the default project storage bucket
  exports.dbTriggersFSCreateWriteStream = functions.database
    .ref('/ftp_fs_triggers/{pushId}')
    .onWrite(event =&gt; {
      const trigger = event.data.val()
      const fileName = trigger.file_name // i.e. : trigger.file_name = '20170601.tar.gz'
      return saveFTPFileWithFSCreateWriteStream(trigger.file_name)
      // This fails with the following error in firebase console:
      // Error: EROFS: read-only file system, open '20170601.tar.gz' at Error (native)
    })
  // Listens for new triggers added to /ftp_bucket_triggers/:pushId and calls the saveFTPFileWithBucketUpload
  // function to save the file in the default project storage bucket
  exports.dbTriggersBucketUpload = functions.database
    .ref('/ftp_bucket_triggers/{pushId}')
    .onWrite(event =&gt; {
      const trigger = event.data.val()
      const fileName = trigger.file_name // i.e. : trigger.file_name = '20170601.tar.gz'
      return saveFTPFileWithBucketUpload(trigger.file_name)
      // This fails with the following error in firebase console:
      /*
      Error: Uncaught, unspecified "error" event. ([object Object])
      at Pumpify.emit (events.js:163:17)
      at Pumpify.onerror (_stream_readable.js:579:12)
      at emitOne (events.js:96:13)
      at Pumpify.emit (events.js:188:7)
      at Pumpify.Duplexify._destroy (/user_code/node_modules/@google-cloud/storage/node_modules/duplexify/index.js:184:15)
      at /user_code/node_modules/@google-cloud/storage/node_modules/duplexify/index.js:175:10
      at _combinedTickCallback (internal/process/next_tick.js:67:7)
      at process._tickDomainCallback (internal/process/next_tick.js:122:9)
      */
    })
  // [END database triggers]
  </code></pre>