Get Download URL from file uploaded with Cloud Functions for Firebase

Question

After uploading a file in Firebase Storage with Functions for Firebase, I'd like to get the download url of the file.

I have this :

...

return bucket
    .upload(fromFilePath, {destination: toFilePath})
    .then((err, file) => {

        // Get the download url of file

    });

The object file has a lot of parameters. Even one named mediaLink. However, if I try to access this link, I get this error :

Anonymous users does not have storage.objects.get access to object ...

Can somebody tell me how to get the public download Url?

Thank you

Answer 1

You'll need to generate a signed URL using getSignedURL via the @google-cloud/storage NPM module.

Example:

const gcs = require('@google-cloud/storage')({keyFilename: 'service-account.json'});
// ...
const bucket = gcs.bucket(bucket);
const file = bucket.file(fileName);
return file.getSignedUrl({
  action: 'read',
  expires: '03-09-2491'
}).then(signedUrls => {
  // signedUrls[0] contains the file's public URL
});

You'll need to initialize @google-cloud/storage with your service account credentials as the application default credentials will not be sufficient.

UPDATE: The Cloud Storage SDK can now be accessed via the Firebase Admin SDK, which acts as a wrapper around @google-cloud/storage. The only way it will is if you either:

1. Init the SDK with a special service account, typically through a second, non-default instance.
2. Or, without a service account, by giving the default App Engine service account the "signBlob" permission.