Develop Reference

Google Calendar API for a simple script

I'm trying to get a simple script (python) to work against the google calendar API and don't seem to be able to get the authentication to work properly. Its for a basic raspberry pi based thing I'm trying to make at home, and I need to just grab all the events from my google calendar.
I started with the code examples on the website, but because my script is totally server side, There was no way I could get the auth challenge step to work properly (it tried with lynx, but didn't work)
I then found examples with a service account - which seemed like the right thing as it didn't need the challenge flow. Furthermore, getting the creds_with_subject, seemed like the right approach to actually get a token related to the google account that owns the calendar. I think I got it all strung together, but then I don't actually get anything listed (as a start, I was using the calendar.list() endpoint to list the calendars out). The authentication step seemed to work (no errors) - but the ensuing list was empty. I'm guessing because my service account token wasn't associated/allowed to access my google account calendar. I've enabled the calendar API in the project to which the service account belongs.
Many of the guides I found seem to mention GSuite, which its not clear if I need
So summary questions:
For this type of usage - is the service account the right approach?
If so, do I need to associate this service account with my google account (that actually owns the calendar)?
It looks like the simple API key work doesn't work any more, but thought I'd check in case there is a simpler way?
do I need GSuite?
from __future__ import print_function
import datetime
import os.path
from googleapiclient.discovery import build
from google_auth_oauthlib.flow import InstalledAppFlow
from google.auth.transport.requests import Request
from google.oauth2.credentials import Credentials
from google.oauth2 import service_account
SCOPES = ['https://www.googleapis.com/auth/calendar']
def main():
"""Shows basic usage of the Google Calendar API.
Prints the start and name of the next 10 events on the user's calendar.
"""
creds = service_account.Credentials.from_service_account_file("credentials.json", scopes=SCOPES);
creds_with_subjects = creds.with_subject("<my real account>#gmail.com");
print(creds);
print(creds_with_subjects);
service = build('calendar', 'v3', credentials=creds_with_subjects)
print(creds);
print("Getting Calendar list");
page_token = None
while True:
calendar_list = service.calendarList().list(pageToken=page_token).execute()
print(calendar_list);
page_token = calendar_list.get('nextPageToken')
if not page_token:
break
if __name__ == '__main__':
main()

Creating a service account is not enough. You also have to perform domain wide delegation and impersonate your user.
The main purpose of granting domain-wide authority to a service account is for these accounts to be able to access data on behalf of a user in your domain as otherwise the service account acts like just another account and it is trying to access its own data from Calendar, hence the empty response you are receiving.
To impersonate your user, you will have to follow the steps below:
Create a Credentials object from the service account's credentials and the scopes your application needs access to:
from google.oauth2 import service_account
SCOPES = ['SCOPE1', 'SCOPE2', ...]
SERVICE_ACCOUNT_FILE = '/path/to/service.json'
credentials = service_account.Credentials.from_service_account_file(
SERVICE_ACCOUNT_FILE, scopes=SCOPES)
Delegate domain-wide authority:
delegated_credentials = credentials.with_subject('YOURADDRESS#DOMAIN.COM')
However, in order to do this, you need to have a Google Workspace domain.
Reference
Using OAuth 2.0 for Server to Server Applications;
Authorizing Requests to the Google Calendar API.

How do I authorize with Google without staying signed in to Google in my browser

I'm making a desktop app in Python that sends mail from Gmail. The problem is that after receiving consent (OAuth 2) through the browser, the user for whom the software receives the consent, continues to be logged in to the browser in Gmail. Is there a way to go through the authorization process without staying logged in to Gmail in your browser?

What you are referring to is Oauth2. Oauth2 gives users the ability to grant applications like yours consent to access their private data. Private data is data that is owned by someone. My gmail data is mine your application can not use it unless I grant you access.
Is there a way to go through the authorization process without staying logged in to Gmail in your browser?
Lets clear up some confusion in this statement you mention authorization which is correct a user is authorizing your application to access their data. Yet you also mention logged in which has nothing to do with authorization. Logging in a user is authentication and is not part of Oauth2. It is part of something else called openid connect.
As for how to request authorization of a user without using the browser. Once the user has consented to your application accessing my data once then your application should have what its called a refresh token, this refresh token can be used at a latter time for your application to request a new access token. Granting you access to may data without using the browser to access my data again. So you could store this refresh token in the backend some where and use that to continue to access the users data without needing to use the browser again.
storing user credentials in an installed application
It is hard to know exactly what you are doing since you did not include any code in your question, and your question is a little unclear.
In the following example please note how the users credentials are stored in gmail.dat using this code in an installed application will cause it to load the refresh token the next time the user runs the app meaning that the consent screen should not be shown, as the credentials are already stored for that user.
def initialize_gmail():
"""Initializes the gmail service object.
Returns:
analytics an authorized gmail service object.
"""
# Parse command-line arguments.
parser = argparse.ArgumentParser(
formatter_class=argparse.RawDescriptionHelpFormatter,
parents=[tools.argparser])
flags = parser.parse_args([])
# Set up a Flow object to be used if we need to authenticate.
flow = client.flow_from_clientsecrets(
CLIENT_SECRETS_PATH, scope=SCOPES,
message=tools.message_if_missing(CLIENT_SECRETS_PATH))
# Prepare credentials, and authorize HTTP object with them.
# If the credentials don't exist or are invalid run through the native client
# flow. The Storage object will ensure that if successful the good
# credentials will get written back to a file.
storage = file.Storage('gmail.dat')
credentials = storage.get()
if credentials is None or credentials.invalid:
credentials = tools.run_flow(flow, storage, flags)
http = credentials.authorize(http=httplib2.Http())
# Build the service object.
service = build('gmail ', 'v1', http=http)
return service

How to get a GCP Bearer token programmatically with python

gcloud auth print-access-token gives me a Bearer token that I can use later on; however, this is a shell command. How would I obtain one programmatically via the Google Cloud Python API?
I see a prior example using oauth2client, but oauth2client is now deprecated. How would I do this with google.auth and oauthlib?

While the above answer is quite informative, it misses one important point - credentials object obtained from google.auth.default() or compute_engine.Credentials() will not have token in it. So back to the original question of what is the programmatic alternative to gcloud auth print-access-token, my answer would be:
import google.auth
import google.auth.transport.requests
creds, project = google.auth.default()
# creds.valid is False, and creds.token is None
# Need to refresh credentials to populate those
auth_req = google.auth.transport.requests.Request()
creds.refresh(auth_req)
# Now you can use creds.token
I'm using the official google-auth package and default credentials, which will get you going both in local dev and on remote GCE/GKE app.
Too bad this is not properly documented and I had to read google-auth code to figure our how to obtain the token.

The answer depends on your environment and how you want to create / obtain credentials.
What are Google Cloud Credentials?
Google Cloud credentials are an OAuth 2.0 token. This token has at a minimum an Access Token and optionally a Refresh Token, Client ID Token, and supporting parameters such as expiration, Service Account Email or Client Email, etc.
The important item in Google Cloud APIs is the Access Token. This token is what authorizes access to the cloud. This token can be used in programs such as curl, software such as python, etc and does not require an SDK. The Access Token is used in the HTTP Authorization header.
What is an Access Token?
An access token is an opaque value generated by Google that is derived from a Signed JWT, more correctly called JWS. A JWT consists of a header and claims (the payload) Json structures. These two Json structures are signed with the Service Account's Private Key. These values are base64 encoded and concatenated to create the Access Key.
The format of an Access Token is: base64(header) + '.' + base64(payload) + '.' + base64(signature).
Here is an example JWT:
Header:
{
"alg": "RS256",
"typ": "JWT",
"kid": "42ba1e234ac91ffca687a5b5b3d0ca2d7ce0fc0a"
}
Payload:
{
"iss": "myservice#myproject.iam.gserviceaccount.com",
"iat": 1493833746,
"aud": "myservice.appspot.com",
"exp": 1493837346,
"sub": "myservice#myproject.iam.gserviceaccount.com"
}
Using an Access Token:
Example that will start a VM instance. Replace PROJECT_ID, ZONE and INSTANCE_NAME. This example is for Windows.
curl -v -X GET -H "Authorization: Bearer <access_token_here>" ^
https://www.googleapis.com/compute/v1/projects/%PROJECT_ID%/zones/%ZONE%/instances/%INSTANCE_NAME%/start
Compute Engine Service Account:
Dustin's answer is correct for this case, but I will include for completeness with some additional information.
These credentials are automatically created for you by GCP and are obtained from the VM Instance metadata. Permissions are controlled by Cloud API access scopes in the Google Console.
However, these credentials have some limitations. To modify the credentials you must stop the VM Instance first. Additionally, not all permissions (roles) are supported.
from google.auth import compute_engine
cred = compute_engine.Credentials()
Service Account Credentials:
Until you understand all of the types of credentials and their use cases, these are the credentials that you will use for everything except for gcloud and gsutil. Understanding these credentials will make working with Google Cloud much simpler when writing programs. Obtaining credentials from a Google Service Account Json file is easy. The only item to make note of is that credentials expire (typically 60 minutes) and either need to be refreshed or recreated.
gcloud auth print-access-token is NOT recommended. Service Account Credentials are the recommended method by Google.
These credentials are created by the Console, gcloud or via programs / APIs. Permissions are assigned to the creditials by IAM and function inside Compute Engine, App Engine, Firestore, Kubernetes, etc. as well as other environments outside of Google Cloud. These credentials are downloaded from Google Cloud and stored in a Json file. Notice the scopes parameter. This defines permissions that are granted to the resulting credentials object.
SCOPES = ['https://www.googleapis.com/auth/sqlservice.admin']
SERVICE_ACCOUNT_FILE = 'service-account-credentials.json'
from google.oauth2 import service_account
cred = service_account.Credentials.from_service_account_file(
SERVICE_ACCOUNT_FILE, scopes=SCOPES)
Google OAuth 2.0 Credentials:
These credentials are derived from a full OAuth 2.0 flow. These credentials are generated when your browser is launched to access Google Accounts for authorizing access. This process is much more complicated and requires a fair amount of code to implement and requires a built-in web server for the callback for authorization.
This method provides additional features such as being able to run everything in a browser, example you can create a Cloud Storage File Browser, but be careful that you understand the security implications. This method is the technique used to support Google Sign-In, etc. I like to use this method to authenticate users before allowing posting on websites, etc. The possibilities are endless with correctly authorized OAuth 2.0 identities and scopes.
Example code using google_auth_oauthlib:
from google_auth_oauthlib.flow import InstalledAppFlow
flow = InstalledAppFlow.from_client_secrets_file(
'client_secrets.json',
scopes=scope)
cred = flow.run_local_server(
host='localhost',
port=8088,
authorization_prompt_message='Please visit this URL: {url}',
success_message='The auth flow is complete; you may close this window.',
open_browser=True)
Example code using the requests_oauthlib library:
from requests_oauthlib import OAuth2Session
gcp = OAuth2Session(
app.config['gcp_client_id'],
scope=scope,
redirect_uri=redirect_uri)
# print('Requesting authorization url:', authorization_base_url)
authorization_url, state = gcp.authorization_url(
authorization_base_url,
access_type="offline",
prompt="consent",
include_granted_scopes='true')
session['oauth_state'] = state
return redirect(authorization_url)
# Next section of code after the browser approves the request
token = gcp.fetch_token(
token_url,
client_secret=app.config['gcp_client_secret'],
authorization_response=request.url)

In some cases, it's not possible to set environment variables on the server or container while needing a Bearer access token to call Google cloud APIs. I present the following to solve such problem:
# pip3 install google-auth
# pip3 install requests
import google.auth
import google.auth.transport.requests
from google.oauth2 import service_account
credentials = service_account.Credentials.from_service_account_file('/home/user/secrets/hil-test.json', scopes=['https://www.googleapis.com/auth/cloud-platform'])
auth_req = google.auth.transport.requests.Request()
credentials.refresh(auth_req)
credentials.token
The last line would print the access token for calling Google cloud APIs. Replace ya29<REDACTED> in the following curl command with the printed token from python as a test:
curl https://example.googleapis.com/v1alpha1/projects/PROJECT_ID/locations -H "Authorization: Bearer ya29<REDACTED>"
It may not make sense to execute python to get the token then curl in BASH to call an API. The purpose is to demonstrate getting the token to call Google cloud Alpha API which may not have any Python client library but REST API. Developers can then use Python requests HTTP library to call the APIs.

import google.auth
import google.auth.transport.requests
# getting the credentials and project details for gcp project
credentials, your_project_id = google.auth.default(scopes=["https://www.googleapis.com/auth/cloud-platform"])
#getting request object
auth_req = google.auth.transport.requests.Request()
print(credentials.valid) # prints False
credentials.refresh(auth_req) #refresh token
#cehck for valid credentials
print(credentials.valid) # prints True
print(credentials.token) # prints token

This may not be the recommended way but for Rest API in my application this was an easy way to get the token.
from subprocess import PIPE, Popen
def cmdline(command):
process = Popen(
args=command,
stdout=PIPE,
shell=True
)
return process.communicate()[0]
token = cmdline("gcloud auth application-default print-access-token")
print("Token:"+token)

I found myself here when looking for a way to use the python SDK without creating a service account. I wanted a way to locally develop a script that would run in the cloud. I was able to achieve this by using an artifact of the gcloud command:
export GOOGLE_APPLICATION_CREDENTIALS=~/.config/gcloud/legacy_credentials/<me>/adc.json

Merging suggestions from this post and the google cloud documentation, I wrote an auxiliary function that returns a token. It generates a token if possible, and if not takes it from the environment, then checks that it's valid.
import google
import os
import requests
GOOGLE_APPLICATION_CREDENTIALS = "GOOGLE_APPLICATION_CREDENTIALS"
GCS_OAUTH_TOKEN = "GCS_OAUTH_TOKEN"
SCOPE = "https://www.googleapis.com/auth/cloud-platform"
URL = "https://www.googleapis.com/oauth2/v1/tokeninfo"
PAYLOAD = "access_token={}"
HEADERS = {"content-type": "application/x-www-form-urlencoded"}
OK = "OK"
def get_gcs_token():
"""
Returns gcs access token.
Ideally, this function generates a new token, requries that GOOGLE_APPLICATION_CREDENTIALS be set in the environment
(os.environ).
Alternatively, environment variable GCS_OAUTH_TOKEN could be set if a token already exists
"""
if GOOGLE_APPLICATION_CREDENTIALS in os.environ:
# getting the credentials and project details for gcp project
credentials, your_project_id = google.auth.default(scopes=[SCOPE])
# getting request object
auth_req = google.auth.transport.requests.Request()
credentials.refresh(auth_req) # refresh token
token = credentials.token
elif GCS_OAUTH_TOKEN in os.environ:
token = os.environ[GCS_OAUTH_TOKEN]
else:
raise ValueError(
f"""Could not generate gcs token because {GOOGLE_APPLICATION_CREDENTIALS} is not set in the environment.
Alternatively, environment variable {GCS_OAUTH_TOKEN} could be set if a token already exists, but it was not"""
)
r = requests.post(URL, data=PAYLOAD.format(token), headers=HEADERS)
if not r.reason == OK:
raise ValueError(
f"Could not verify token {token}\n\nResponse from server:\n{r.text}"
)
if not r.json()["expires_in"] > 0:
raise ValueError(f"token {token} expired")
return token

Official documentation code example
I followed this official documentation for Cloud Functions, which works for any GCP API:
auth_req = google.auth.transport.requests.Request()
id_token = google.oauth2.id_token.fetch_id_token(
auth_req,
# This is an OAuth authorisation scope that you must pass
# depending on the API.
# You can see an example of the need for this scope here: https://cloud.google.com/bigquery/docs/reference/rest/v2/jobs/insert#authorization-scopes
"https://www.googleapis.com/auth/bigquery"
)
Now, you can use id_token in the Authorisation header:
headers = {'Authorization': f'Bearer {id_token}'}

Service Accounts, web OAuth and the Directory API

I'm having issues with the Directory API + Service Accounts (Google APIs). This is my current setup:
A web page has an OAuth2 login link like this: https://accounts.google.com/o/oauth2/auth?access_type=offline&state=%2Fprofile&redirect_uri=##REDIR##&response_type=code&client_id=##CLIENTID##&scope=https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fuserinfo.email+https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fadmin.directory.user.readonly
Users log in there, authorizing the app to access the Directory API in read-only mode on their behalf.
I then try to retrieve the users of the domain of a given user (by knowing its email address), using the Directory API.
Python code:
from apiclient.discovery import build
from oauth2client.client import SignedJwtAssertionCredentials
import httplib2
CLIENT_ID = "xzxzxzxzxzxz.apps.googleusercontent.com"
APP_EMAIL = "xzxzxzxzxzxz#developer.gserviceaccount.com"
SCOPES = ('https://www.googleapis.com/auth/admin.directory.user.readonly')
f = file('key.p12', 'rb')
key = f.read()
f.close()
credentials = SignedJwtAssertionCredentials(APP_EMAIL, key, SCOPES, sub="user#example.com")
http = httplib2.Http()
http = credentials.authorize(http)
directory_service = build('admin', 'directory_v1', http=http)
users = directory_service.users().list(domain="example.com").execute()
print users
I have also tried setting sub="user#example.com" to the app owner like this sub="appowner#company.com", to no avail.
Another thing I have tried is not using impersonation at all (ie. removing the sub=xx part), which leads me to this error:
apiclient.errors.HttpError: https://www.googleapis.com/admin/directory/v1/users?domain=example.com&alt=json returned "Not Authorized to access this resource/api">
Using impersonation always yields me this. I have verified it has to do with the scopes and the api which I try to call:
oauth2client.client.AccessTokenRefreshError: access_denied
Now, the actual questions:
Should I be using service accounts? For me, it is the most convenient way as I don't have to be storing tokens which can be outdated altogether.
If service accounts are the way to go, what am I doing wrong in the way I use them? Impersonation with either the Google Apps administrator account (which logs in via OAuth web) or the app owner account does not seem to work.

Google Contact API - Auth2.0

I'm looking for a good way to retrieve every emails address of my contacts from a google account for a "desktop" application in Python.
In a first time, I created an app via Google Code. I toggled Google Plus API, retrieving most of my user data, but not any of my contacts.
I started investigate, and I found a lot of stuff, but most of them was outdated.
I found a good way to retrieve my contacts, using gdata library but granting me a full read/write access on it, via https://www.google.com/m8/feeds with no feedback.
self.gd_client = gdata.contacts.client.ContactsClient(source='MyAppliName')
self.gd_client.ClientLogin(email, password, self.gd_client.source)
According to the official 'google contact api' google group, which migrated to stackoverflow, read only access is broken.
By the way, I'm not a huge fan of 'Trust my application, I use read only access, I swear."
I found the google api playground at https://developers.google.com/oauthplayground in which they use OAuth2.0 token with most of apis, including contact, toggling a webpage:
Google OAuth 2.0 Playground is requesting permission to:
Manage your contacts
According to this playground, it's possible to use OAuth2.0 with google contact api, but I have no idea how to add https:// www.google.com/m8/feeds to my scope, which doesn't appear on the list.
Is there an other way to do that ?

If this question is still open for you, here is some sample code how to use oauth2 and Google Contact API v3:
import gdata.contacts.client
from gdata.gauth import AuthSubToken
from oauth2client import tools
from oauth2client.client import flow_from_clientsecrets
from oauth2client.file import Storage
def oauth2_authorize_application(client_secret_file, scope, credential_cache_file='credentials_cache.json'):
"""
authorize an application to the requested scope by asking the user in a browser.
:param client_secret_file: json file containing the client secret for an offline application
:param scope: scope(s) to authorize the application for
:param credential_cache_file: if provided or not None, the credenials will be cached in a file.
The user does not need to be reauthenticated
:return OAuth2Credentials object
"""
FLOW = flow_from_clientsecrets(client_secret_file,
scope=scope)
storage = Storage(credential_cache_file)
credentials = storage.get()
if credentials is None or credentials.invalid:
# Run oauth2 flow with default arguments.
credentials = tools.run_flow(FLOW, storage, tools.argparser.parse_args([]))
return credentials
SCOPES = ['https://www.google.com/m8/feeds/', 'https://www.googleapis.com/auth/userinfo.email']
credentials = oauth2_authorize_application('client-secret.json', scope=SCOPES)
token_string = credentials.get_access_token().access_token
# deprecated!
# auth_token = AuthSubToken(token_string, SCOPES)
with open('client-secret.json') as f:
oauth2_client_secret = json.load(f)
auth_token = gdata.gauth.OAuth2Token(
client_id=oauth2_client_secret['web']['client_id'],
client_secret=oauth2_client_secret['web']['client_secret'],
scope=SCOPES,
user_agent='MyUserAgent/1.0',
access_token=credentials.get_access_token().access_token,
refresh_token=credentials.refresh_token)
client = gdata.contacts.client.ContactsClient(auth_token=auth_token)
query = gdata.contacts.client.ContactsQuery()

The request should look like:
https://accounts.google.com/o/oauth2/auth?
scope=https%3A%2F%2Fwww.google.com%2Fm8%2Ffeeds&
state=<myState>&
redirect_uri=<Redirect URI>&
response_type=code&
client_id=<my Client ID>&approval_prompt=force
This will obtain read/write access to the user's contacts.