Q:

issues deleting an image using Cloud Functions for Firebase and @google-cloud/storage

I'm trying to create a script in Cloud Functions for Firebase that will react to a db event and remove an image that has its path in one of the params ("fullPath").
this is the code i'm using:
'use strict';

const functions = require('firebase-functions');
const request = require('request-promise');
const admin = require('firebase-admin');
const gcs = require('@google-cloud/storage')({
    projectId: 'XXXXXXX',
    credentials: {
        // removed actual credentials from here
    }});

admin.initializeApp(functions.config().firebase);

// Deletes the user data in the Realtime Datastore when the accounts are deleted.
exports.removeImageOnNodeRemoval = functions.database
    .ref("images/{imageId}")
    .onWrite(function (event) {

        // exit if we are creating a new record (when no previous data exists)
        if (!event.data.previous.exists()) {
            console.log("a new image added");
            return;
        }

        // exit if we are just trying to update the image
        if (event.data.exists()) {
            console.log("image is been modified");
            return;
        }

        let previousData = event.data.previous.val();
        if(!previousData || !previousData.fullPath){
            console.log("no data in the previous");
            return;
        }

        let bucketName = 'XXXXXXX';
        console.log("default bucketName", gcs.bucket(bucketName));
        let file = gcs.bucket(bucketName).file(previousData.fullPath);
        console.log('the file /'+previousData.fullPath, file);

        file.exists().then(function(data) {
            let exists = data[0];
            console.info("file exists", exists);
        });

        file.delete().then(function() {
            // File deleted successfully
            console.log("image removed from project", previousData.fullPath);

        }).catch(function(error) {
            // Uh-oh, an error occurred!
            console.error("failed removing image from project", error, previousData);
        });

    });

the error i'm getting:
failed removing image from project { ApiError: Not Found
    at Object.parseHttpRespBody (/user_code/node_modules/@google-cloud/storage/node_modules/@google-cloud/common/src/util.js:192:30)
    at Object.handleResp (/user_code/node_modules/@google-cloud/storage/node_modules/@google-cloud/common/src/util.js:132:18)
    at /user_code/node_modules/@google-cloud/storage/node_modules/@google-cloud/common/src/util.js:465:12
    at Request.onResponse [as _callback] (/user_code/node_modules/@google-cloud/storage/node_modules/retry-request/index.js:120:7)
    at Request.self.callback (/user_code/node_modules/@google-cloud/storage/node_modules/request/request.js:188:22)
    at emitTwo (events.js:106:13)
    at Request.emit (events.js:191:7)
    at Request.<anonymous> (/user_code/node_modules/@google-cloud/storage/node_modules/request/request.js:1171:10)
    at emitOne (events.js:96:13)
    at Request.emit (events.js:188:7)
    at IncomingMessage.<anonymous> (/user_code/node_modules/@google-cloud/storage/node_modules/request/request.js:1091:12)
    at IncomingMessage.g (events.js:291:16)
    at emitNone (events.js:91:20)
    at IncomingMessage.emit (events.js:185:7)
    at endReadableNT (_stream_readable.js:974:12)
    at _combinedTickCallback (internal/process/next_tick.js:74:11)
    at process._tickDomainCallback (internal/process/next_tick.js:122:9)
  code: 404,
  errors: [ { domain: 'global', reason: 'notFound', message: 'Not Found' } ],
  response: undefined,
  message: 'Not Found' } { contentType: 'image/png',
  fullPath: 'images/1491162408464hznsjdt6oaqtqmukrzfr.png',
  name: '1491162408464hznsjdt6oaqtqmukrzfr.png',
  size: '44.0 KB',
  timeCreated: '2017-04-02T19:46:48.855Z',
  updated: '2017-04-02T19:46:48.855Z' }

i have tried with and without credentials to google-cloud/storage (thinking they might get auto filled while im in firebase.functions - do i need them?). i have tried adding a slash to the file's path. i have validated that the file actually exists in the bucket (even tho file.exists() returns false). the credentials i provided are for an iam i created with admin privileges for the storage service.
i have also enable the billing account on the free plan.
any ideas?

A:

ok, so i got this solved. here are my conclusions:

you need to add to your buckets name the ".appspot.com". Its not written anywhere in the docs and getting your bucket name in firebase is hard enough for someone that is not familiar in the google cloud. I hope they will add this little peace of information into their docs or make it clear what is your bucket's name in firebase.
use the environment variable process.env.GCLOUD_PROJECT, it should have your project id that is identical to your bucket id in firebase. again, remember to add the .appspot.com suffix to it.
regarding the credentials to GCS, you don't need to provide them when using cloud functions for firebase. you seem to be authenticated already.

A:

Make sure your bucket name doesn't include gs://
Eg. instead of gs://my-project-id.appspot.com use my-project-id.appspot.com 
let bucket = gcs.bucket('my-project-id.appspot.com')
This may happen to you (as it did to me) if you copy your bucket name from, for instance, Android code, where you can use full URL to connect with storage, ie. storage.getReferenceFromUrl('gs://my-proj...
.
Also, it seems the projectId variable you use to initialise gcs doesn't need the appspot.com suffix (but it shouldn't break if you have it included). Ie. projectId:'my-project-id' should be suffice.
Lastly, the GCS node package docs states you need to generate separate JSON to pass as keyFilename to test things locally. Good news is - you can use the Firebase Admin SDK key, as described in the Get Started Server/Admin docs instead.

