GDrive export using Service Account creds fails with 404

Question

I have a script to export text from a GDrive file using an OAuth client, which works perfectly well -

import googleapiclient.discovery as google

from apiclient.http import MediaIoBaseDownload

from google_auth_oauthlib.flow import InstalledAppFlow

from google.auth.transport.requests import Request

import datetime, io, os, pickle

Scopes=" ".join(['https://www.googleapis.com/auth/drive.file',
                 'https://www.googleapis.com/auth/drive.metadata',
                 'https://www.googleapis.com/auth/drive.readonly'])

TokenFile="token.pickle"

def init_creds(clientfile,
               scopes,
               tokenfile=TokenFile):            
    token=None
    if os.path.exists(tokenfile):
        with open(tokenfile, 'rb') as f:
            token=pickle.load(f)            
    if (not token or
        not token.valid or
        token.expiry < datetime.datetime.utcnow()):    
        if (token and
            token.expired and
            token.refresh_token):
            token.refresh(Request())
        else:
            flow=InstalledAppFlow.from_client_secrets_file(clientfile, scopes)
            token=flow.run_local_server(port=0)
        with open(tokenfile, 'wb') as f:
            pickle.dump(token, f)
    return token

def export_text(id,
                clientfile,
                scopes=Scopes):
    creds=init_creds(clientfile=clientfile,
                     scopes=scopes)
    service=google.build('drive', 'v3', credentials=creds)
    request=service.files().export_media(fileId=id,
                                         mimeType='text/plain')
    buf=io.BytesIO()
    downloader, done = MediaIoBaseDownload(buf, request), False
    while done is False:
        status, done = downloader.next_chunk()
        destfilename="tmp/%s.txt" % id
    return buf.getvalue().decode("utf-8")

if __name__=='__main__':
    print (export_text(id="#{redacted}"
                       clientfile="/path/to/oath/client.json"))

But it's a pain to have to go through the OAuth flow every time, and since it's only me using the script I want to simplify things and use a Service Account instead, following on from this post -

Google Drive API Python Service Account Example

My new Service Account script, doing exactly the same thing, is as follows -

import googleapiclient.discovery as google

from oauth2client.service_account import ServiceAccountCredentials

from apiclient.http import MediaIoBaseDownload

import io

Scopes=" ".join(['https://www.googleapis.com/auth/drive.file',
                 'https://www.googleapis.com/auth/drive.metadata',
                 'https://www.googleapis.com/auth/drive.readonly'])

def export_text(id,
                clientfile,
                scopes=Scopes):
    creds=ServiceAccountCredentials.from_json_keyfile_name(clientfile,
                                                           scopes)
    service=google.build('drive', 'v3', credentials=creds)
    request=service.files().export_media(fileId=id,
                                         mimeType='text/plain')
    buf=io.BytesIO()
    downloader, done = MediaIoBaseDownload(buf, request), False
    while done is False:
        status, done = downloader.next_chunk()
        destfilename="tmp/%s.txt" % id
    return buf.getvalue().decode("utf-8")

if __name__=='__main__':
    print (export_text(id="#{redacted}",
                       clientfile="path/to/service/account.json"))

but when I run it for the same id, I get the following -

googleapiclient.errors.HttpError: <HttpError 404 when requesting https://www.googleapis.com/drive/v3/files/#{redacted}/export?mimeType=text%2Fplain&alt=media returned "File not found: #{redacted}.">

It feels like the Service Account script is passing the authentication step (ie Service Account creds are okay) but then failing when trying to fetch the file - weird as I can fetch it fine using the OAuth version :/

Any thoughts on what might be causing this 404 error in the Service Account version, given the OAuth client version clearly works for the same id?

Answer 1

Answer:

You need to share your file with the service account.

More Information:

As you would with any file, you need to give a user explicit permissions to be able to see it. As a service account is a separate entitiy to you, this goes for them as well.

Using the file sharing settings (you can just do this in the Drive UI by right-clicking the file and hitting Share), give the email address of the service account the correct permission (read/write). The email address of the service account is in the form:

[email protected]