I have a Google Cloud Function. I also have a web application. I want to authenticate requests to the cloud function by using a service account.
I have the json key file.
I know that I have to follow https://cloud.google.com/functions/docs/securing/authenticating#service-to-function. But that is leading me to an IAP page that does not apply to google cloud functions.
Another similar instructions are found in https://developers.google.com/identity/protocols/oauth2/service-account
But if I am following the python library code, I end up with the sample code there :
import googleapiclient.discovery
sqladmin = googleapiclient.discovery.build('sqladmin', 'v1beta3', credentials=credentials)
response = sqladmin.instances().list(project='exciting-example-123').execute()
This does not directly relate to invoking a cloud function.
This question's answer somewhat deals with my requirement but is using a Call API which is only suitable for testing.
Also, I want to expose this API to multiple applications using another tech like .net. So I believe the best option for me will be to use the HTTP method (given on the same page):
https://developers.google.com/identity/protocols/oauth2/service-account#httprest
But whatever I do I am unable to get the signature right.
Any help to get this sorted will be highly appreciated as I am stuck on this for the past few days.
You can use the Google auth library like this
from google.oauth2.id_token import fetch_id_token
from google.auth.transport import requests
audience="my_audience"
r = requests.Request()
token=fetch_id_token(r,audience)
print(token)
The fetch_id_token method will use the default credentials
The service account key file defined in the environment variable GOOGLE_APPLICATION_CREDENTIALS
The service account loaded in the Google Cloud environment
For now, I followed this answer in PHP
In the claims section, I removed the scope. Instead added a claim of target_audience.
"target_audience" => "google-function-http-trigger"
the cloud function http trigger will look like https://us-central1-test-project-name.cloudfunctions.net/function-name",
This will give the required assertion key.
Then I follow https://developers.google.com/identity/protocols/oauth2/service-account#httprest to get the id_token
Then with the id_token as the bearer token we can call the cloud function.
please note that the token expires depending on the time set in the "exp" claim. Once expired you have to redo the steps to generate the new id_token
I want to authenticate requests to the cloud function by using a service account.
I am not sure I understand the context correctly, but I would try to assign a roles/cloudfunctions.invoker IAM role to that service account (which is used to run your code in the web application) - see Cloud Functions IAM Roles .
In that case a code under that service account "Can invoke an HTTP function using its public URL"
I reckon no json keys are required in this case.
Related
I have a Firebase (node.js) cloud function that pulls in some data from my app's Firestore database and builds some static content for the web. I'd like that same cloud function to deploy the static content to Firebase hosting via the Firebase Hosting API, creating a static portion of my site with user generated content.
I understand the general flow thanks to the somewhat clear walkthrough, but am stuck on the first step: getting an access token to call the API. Obviously I'm not going to insecurely put my service account key in the cloud function itself, so the example in the walkthrough doesn't apply. And as I understand it, Firebase cloud functions are already associated with a service account, so presumably there's some way to get an access token to call other Google Cloud services from a cloud function.
So how do I get an access token to call the hosting API from a Cloud Function?
There are some red flags that make me think this isn't possible. For example, all of the uses cases in the walkthrough allude to other server environments, as opposed to Google Cloud environments. And yet, this use case is the third bullet in the use case list in the walkthrough.
I've searched extensively here and elsewhere for some guidance, but aren't finding anything. There are some older questions about accessing hosted files from a cloud function that aren't relevant. This promising question from 5 years ago about this exact use case only has dead ends.
You can use the google-auth-library package in Cloud Functions to a get a token as shown below:
import { GoogleAuth } from "google-auth-library";
const token = await new GoogleAuth({
scopes: ["https://www.googleapis.com/auth/cloud-platform"],
}).getAccessToken();
If you use Firebase Admin SDK in the Cloud Functions, then you can get an access token of the default service account as shown below (do ensure the service account has required permissions):
import { initializeApp } from "firebase-admin/app";
const admin = initializeApp();
const token = await admin.options.credential?.getAccessToken();
// ^ Google OAuth2 access token object used to authenticate with Firebase services.
I have a google cloud function in Java.
Client will invoke the function using HTTP trigger URL.
But that is not secure. I have gone through some docs saying that you should pass a token or client ID and then verify it in server side.
Can anyone explain that in detail and please provide a code example if any.
My doubt is to authenticate the client while they invoke the function using Http trigger
This page explains quite well all the capacity that you have to authenticate a requester on Cloud Functions.
If you have users, the best way is to use Firebase Auth (our Google Cloud Identity Platform which is simply a more advance solution than Firebase Auth with more features)
However, you need to grant all you user with cloudfunction.invoker role, to allow them to invoke the Cloud Functions. It could be difficult. You can also perform the check on your side, but in this case you remove the security (filter) layer of google and you have to check all the traffic by yourselves (not really safe, in term of billing and in case of attack).
The latest solution, API keys, is not recommended, especially for the users. But for machine to machine it's sometime the only solution. However, there isn't out of the box solution and for this I wrote an article, that explains how to create a Cloud Endpoint (or now a Cloud API Gateway which is the serverless solution of Cloud Endpoint with ESPv2) to accept API Keys.
With this latest solution, if you change your security definition, you can also accept OAuth2 tokens coming from Firebase Auth (or Cloud Identity Platform), but this time, you don't need to grant all the users on your Cloud Functions IAM role. The token only need to be valid and it's the Cloud Endpoint service account which is used to perform the call (and thus which needs to be authorized on the Cloud Functions).
In addition, because you can accept OAuth2 token, you can also accept non Google token, and thus have your users in any IDP OAuth2 compliant (KeyCloak, Okta,...)
You could use external OAuth server like keycloack (https://github.com/keycloak/keycloak), or use somethging like Json Web Tokens -- https://jwt.io/ -- available for various languages, siutable for microservices.
When sending SMS to Twilio, Twilio sends several requests to a specified URL to give a status of that SMS delivery through webhooks. I want to make this callback asynchronous, so I developed a Cloud Function that sends a representation of the request to a Cloud Task that itself reach a dedicated endpoint of my app that recreate and simulate the Twilio request internally.
Twilio signs his requests using:
my twilio account's secret key
the absolute URL that it reaches out
and the body of his request
So on my backend, I should know which endpoint Twilio reached out initially. I want to do it inside the Cloud Function, and I want to do it programmatically because this "asynchronous webhook" is also used when people answers to SMS.
The current URL of my webhook has the following format:
https://<location>-<project>.cloudfunctions.net/<cloud function name>/<some SMS uuid>
The current payload sent to my Cloud Task is the following:
absoluteUri: req.protocol + '://' + req.hostname + req.originalUrl,
relativeUri: req.originalUrl,
queryParams: req.query,
headers: req.headers,
body: req.body,
The problem is that req.originalUrl do not contain the full URI, my absoluteUri is currently:
https://<location>-<project>.cloudfunctions.net/<some SMS uuid>
So here is my question: inside a Cloud Function, is there a way to get its name programmatically?
I'm using python 3.9 and get the Cloud Function name from the curiously named "K_SERVICE" environment variable.
import os
print("Current Cloud Function Name {}".format(os.environ.get('K_SERVICE')))
Enjoy them while you can, Google are removing more and more useful environment variables with every new language version.
https://cloud.google.com/functions/docs/configuring/env-var#python_37_and_go_111
As the Cloud Function name is the entry point and should be hardcoded, I ended up writing a deploy script that sed some placeholder.
Looks very ugly, if you have a better way it will be welcome.
This is my first post here. I am sorry if it's a repost, but I've been searching for more than one month for the answer to solve my problem in all websites and forums and until now... no answers!
My goal is to make a Gmail pub/sub watch() to make an action whenever I receive a new email.
To do so, according to the developer's website, I need to subscribe to Gmail watch() on a daily basis with the code:
request = {
'labelIds': ['INBOX'],
'topicName': 'projects/myproject/topics/mytopic'
}
gmail.users().watch(userId='me', body=request).execute()
Until now i have this a working scheduled task with a service account, with INVOKER Permissions. This part just works fine.
In my "initial autorization function" i have:
const {google} = require('googleapis');
// Retrieve OAuth2 config
const oauth2Client = new google.auth.OAuth2(
process.env.CLIENT_ID,
process.env.CLIENT_SECRET,
process.env.CALLBACK_URL
);
exports.oauth2init = (req, res) => {
// Define OAuth2 scopes
const scopes = [
'https://www.googleapis.com/auth/gmail.modify'
];
// Generate + redirect to OAuth2 consent form URL
const authUrl = oauth2Client.generateAuthUrl({
access_type: 'offline',
scope: scopes,
//prompt: 'none'// Required in order to receive a refresh token every time
});
return res.redirect(authUrl);
};
My issue now is that the access token is generated via (prompt) the first time and never updates to a new one ( the token expires after 1hour...) it means this code stops working after that period and a "manual" intervention is required. According with the documentation, i need to use "offline" method and on "prompt" i can omit (only requests permissions on the 1st time) or none (never asks), like is said here.
I managed how to make it work! tomorow i will continue with the process.
Should i post here my working code for reference?
Thanks!
I will rephrase the process you illustrated so that there is no ambiguity.
According the documentation you pushed:
You do not suscribed to watch(), you call watch()
watch() is an API call to the Gmail API that will enable automatic events publication on a pub/sub topic you define given conditions you specified. Who are you watching? On what events?
You suscribe to a Pub/Sub topic that is targeted by your previous watch() call
A process (e.g: Google cloud function) suscribes to the topic and will consume messages sent by the Gmail API
The call is to be renewed at least every seven days
Because Google needs to be sure you still need to monitor the targeted inbox, it needs a renewal from you. Another watch() call will act so.
Cloud scheduler will enable this periodic renewal
this service will trigger your renewal script you put in your question. To do so it needs to be authenticated to the platform that host the script. It is easier if your script is hosted in a google service (cloud function, cloud run,...) and the authent type depends on the target URL form. In all cases YOU DO NEED an authent token in your request header. The token is generated from a service account you created with the right permission to call your script (e.g: cloud run invoker). By default the scheduler has the right to generate a token from it
So far so good. Now comes the tricky part and you don't mention it in your question. How is authenticated your gmail api client? You cannot monitor someone inbox, unless this person gave you the permission to i.e you call the API with the right Oauth2 token. Indeed in the video you point they authenticat the user using this principe which is implemented in their code with Express-oauth2-handler.
So you will have a cloud function to init end user authent and watch to his/her inbox. The renewal should do so but problem is user will not be there for accepting the end user consent. Here comes the offline access but it is beyond the scope of your question. Finally a second functions will suscribe to the pubsub topic and consume the message as you need. See their implementation code which populate a spreadsheet.
The documentation you shared in the comments does not say that you can remove the token from the headers of the service account, also the gmail API documentation you also shared says that you only:
need to grant publish privileges to gmail-api-push#system.gserviceaccount.com. You can do this using the Cloud Pub/Sub Developer Console permissions interface following the resource-level access control instructions.
In order to achieve this basically what you will need is a setup of two cloud functions, the first scheduled function is responsible for setting up the watch(), and you can check this documentation for how to deploy a scheduled function, and the second function being triggered by the pubsub of gmail notifications, you can check this documentation for how to build an event triggered function. Both processes are similar.
NOTE: I have never user the Gmail API, so I am not sure if any extra steps are necessary but then again, the documentation implies that setting up the permissions of that service account is enough to make it work.
EDIT:
As per the information you have shared. The issue is likely that you are not properly setting the Service Account to authenticate with the Cloud Function. As per described in the documentation, you have to grant to the Service Account the role Cloud Functions Invoker in IAM.
Let me know if this fixed the issue.
I'm attempting the verification process for an Apps Script web app that uses the URL Fetch service via class URLFetchApp. Per URLFetchApp documentation, this requires the scope https://www.googleapis.com/auth/script.external_request. I can't find any Google documentation for this scope, and it doesn't appear on this list of OAuth2 scopes. I'm having a hard time demonstrating how my app uses the data provided by the scope when I don't actually know what user data the scope provides. I mean, I don't think I'm using any user data... I'm just calling API executable functions from another Google Apps Script project.
What user data is this scope giving me access to? Or do I just need to explain why/how I'm using URLFetchApp?
If you head over the editor dashboard of your script, you will see further information about this scope stating :
Connect to an external service under project OAuth scopes.
Moreover, when you run your script for the first time, the permissions it is asking for are:
Create a network connection to any external service (e.g., to read or write data)
Therefore, despite not having much more description in the documentation (just in UrlFetchApp), I don't think you are using any user data apart from getting the user to use your script and connect to an external service.
I hope this has helped you. Let me know if you need anything else or if you did not understood something. :)
According the documentation if you wish to use UrlFetchApp Service then external_request is the scope you'll have to add to you manifest. Like it or not.
UrlFetch Service