Do i need to specify all callback URLs in credential page? - google-app-engine

What URLs I need to enter in Google API credential page?
I created an Oauth2 credential for my Google App engine web app.
I entered callback as https://myapp.appspot.com/oauth2callback and it works fine.
Now I am developing V2 and am deploying the app to 2-dot-myapp, Oauth2 stopped working. Do you have to specify callbacks for all versions I am going to deploy?

Yep! Google (or any OAuth provider) will not allow people to log in unless the callback URL provided during authorization exactly matches one that configure on the credentials page.

Related

Methods of Authentication in Go for App Engine

I am building a reservation system in Google App Engine using Go. I need 2 forms of authentication in my program.
Public Form -- form built in Angular that is on our public website. I want my front-end to have some sort of credentials.json file to use when requesting the book and getOpenDates endpoints in my RESTful API running in Go on Google App Engine.
Private Companion App -- protected by username and password that the user supplies in my app built in Flutter. The app is requesting many endpoints in App Engine. I would like to use JWT to authenticate this portion, but I'm not 100% sure JWT is what I need.
I'm not sure if this tutorial on Identity Platform is what I want. I'm very new to App Engine and authentication in general, so I am a bit lost.
Please describe how I could implement these authentication methods in my RESTful API in Go running on Google's App Engine. I think I may be able to implement the username/password method using a tutorial like this but I'm very lost on the 1st form of authentication with just a credentials file as authentication. If I'm going in the complete wrong direction to accomplish what I want please tell me, but what I'm looking for is code or a tutorial describing how to authenticate using these 2 methods. Thanks for any help.
From what I understand, you want to have a golang backend API in App Engine that serves both your web frontend (1.) and your users app (2.).
I am going to suppose that any user with username/password can use both your frontends: the web app and the mobile app with these credentials.
The credentials.jsons are not designed to authenticate users of your services, but rather server to server communication.
With that in mind, I have found the guide Session based authentication in golang, that could help you to set up your backend to accept only authenticated requests over HTTPS. The web browser will automatically save the cookie, however you need to store the cookie in your mobile app.
For much more complicated scenarios for authenticating from different webpages, it is required to use OAuth2 as you can see in this thread. If you don't find any of your requirements listed in here it is probably overkill to use Auth0 nor OAuth2.

Access Google IAP protected API from Angular

My application has 2 modules
Spring boot back-end API
Angular front-end (SPA application)
Both were deployed in Google app engine (GAE).
I used Google IAP for authentication. After enabling the IAP is there any way to generate the IAP JWT token for the different users within the organization to authenticate the APIs from the web client.
I tried token generating mechanism using the Service account. But for my scenario, I just want to authenticate and authorize users not service account. I found this reference to enable the web resource access for users, but it is using cookie based authorization. And it is not the recommended way for the application such as angular.
If you're using IAP to protect your backend api, it means your users have a Google Account or an account managed in Cloud Identity.
In your Angular front-end app, you can retrieve JWT token of your user, with Google Sign-In for Websites.
To easily integrate Google Sign-in with Angular, I recommend you to use ng-gapi from Ruben.
Main lines of the workflow :
Angular uses ng-gapi with Google Sign-in behind the scene
Users are authenticated with their Google Account
You're able to retrieve GoogleUser idToken which is a JWT token.
Each HttpRequest could be executed with Authorization: Bearer JWT
IAP will accept request.
To better understand how to use ng-gapi, check this stackblitz Demo made by creator of lib.
I also suggest you theses resources :
My answer on Stackoverflow about Angular stateless authentication workflow. Just skip the Spring Boot JWT part if you're using IAP.
Google Sign-In for Websites official docs.
Note that you need to use the OAuth 2.0 Client ID configured by Identity-Aware Proxy for your app, and add the correct Authorized JavaScript origins.
Yes, You can generate a JWT token using angular-oauth2-oidc.
Get the default IAP Web App client ID and client secret. Use AuthConfig and redirect to your link after credentials are entered; you can capture the token after they are redirected.
This link has all the details:
https://medium.com/#ishmeetsingh/google-auth-integration-with-angular-5-and-angular-oauth2-oidc-ed01b997e1df
You have told that you tried authenticating from service account. Were you able to generate JWT for service account? I am able to capture the JWT token for individual accounts and use it.
Please give more information on how you authenticated from service account.
Thanks,
Bharath

How to allow mobile apps to login with Facebook and Google to access web service on GAE?

This is in relation to my other question about the need to create a Facebook app.
I've been reading a lot about how to best approach login for mobile apps users (iOS and Android) that access my web service running on Google App Engine. I'm still not clear how to best do it as I would like to offer login with both Google and Facebook. The app and the web service does nothing with Facebook or Google other than I would like to piggyback on their login.
Having only login with Google for GAE is very easy and the same goes for using OpenIDConnect. Facebook unfortunately does not support this.
Reading an old question here on SO where someone wanted to do the same as I it looks like the app should do Facebook Login and then get a token that it passes to my backend which needs to be validated by contacting Facebook. Is this how to do it today?
I also found Google Identity Toolkit, which seem to be what I need. However, I do not have a website or just apps. I would need to have the apps do the Facebook login and somehow provide my web service with something so it can validate the login info.
Later on an app user should be able to log in using randomly Facebook, Google and my custom username/password. The app and the web service should know the user is logged in and authorize it to access the REST API.
How do I accomplish this? BTW, I'm using Go on GAE.
I would really appreciate if someone could explain if there are several options how to do this, pros and cons, and provide an overview of the best approach and what needs to be done.
Many thanks for any help with this!
UPDATE
OK, thanks a lot everyone for the help and pointers. I have successfully run the quickstart sample app for iOS for my GAE backend. Basically, created a Facebook app and permissions credentials on my web service on GAE so that the sample iOS app can log in.
A bit of a gap still before I have an authenticated user in the datastore and can authorize successive API calls.
Main open questions at this point:
how to get the gtoken in the iOS app after successful Facebook or Google login?
should I explicitly call an API on my web service to pass in the gtoken or is this somehow automatic with Gitkit API enabled?
Thanks for any help!
UPDATE
To answer #1 and #2 myself, there's a "successful sign-in url" that can be given in the app engine config so the app knows where to call with the gtoken. Then after that it's like explained in the answers.
Looks like you have an app and a backend on GAE.
If you are using google identity toolkit, it will allow you to signin with Facebook, Google, and email/password.
When user successfully signs in to your app using identity toolkit, your server should receive a gtoken. You have two options here:
Pass the gtoken to your app and save it there. When your app makes API calls to your backend, you app should attach the gtoken to every request. Your backend should verify the gtoken(https://developers.google.com/identity/toolkit/web/required-endpoints) for every API that needs authorization.
Verify the gtoken, generate a token that your backend can recognize/identify the user. Then pass the token to your app and everything else is the same as option 1.
If you do not want to use identity toolkit, you can implement facebook login on your app/backend and use facebook token to communicate between your app and backend.
Whatever your decision is, apps that use your API should pass you something that your backend can recognize/authorize the user.
The answer is about using Google Identity Toolkit (GIT). GIT itself is an identity provider, which would be integrated with your apps and backend. The flow works along these lines:
your app requests login via its GIT API
GIT will perform the federated login with Facebook or other 3rd party provider (transparent to your app) and returns a GIT token to the app (representing a unique user from your end-to-end system perspective, i.e. apps plus backend)
the app makes a request to the backend in which it passes the GIT token
the backend verifies the GIT token validity (using this go GIT client API, for example) and from it can extract the identity of the user and thus validate the request
You can find more detailed info about the backend token validation in the backent endpoint doc, look for these sections in particular:
Understanding the Identity Toolkit cookie/token
Getting information for users
Now the actual token validation on the backend may take a few seconds, so it might not be practical to do it for each and every REST request from the app. If so you'd need to somehow:
save the info that the user of that specific app instance is
authenticated in something like a "session" managed between your app and the backend
map a specific REST request received by the backend to a specific such authenticated "session"
But I'm not sure how exactly is this "session" functionality done in the apps+backend context, I didn't write any apps yet.

How to implement oauth in a chrome app to access a service on an appengine app

I am working on a chrome app which is using an appengine app as a backend. Usually it is possible to use the Google OAuth or the deprecated Google ClientLogin to obtain the ACSID token. The chrome app API provides identity to support oauth2 in chrome apps.
I am able to get an auth token, but am failing in converting it into a valid ACSID token. I have done successfully something similar on android. The key was that when asking for the auth token, I had to specify the specific service ("ah" for the appengine). Could anyone point me out what should be the scope and how to configure the outh2 params in the manifest file?!
Thanks in advance for any help.

How is the user authentication with Google accounts working inside the GAE technically

Applications that run inside the Google App Engine can use Google Accounts for user authentication. I already used this feature and it works great. I just want to know how this is working. Is there a HTTP cookie created? How can an application inside the GAE see that a user is logged in?
The AppEngine SDK takes care of the details for you, but essentially it generates the equivalent of an OAuth request to the Google Account service. All interactions with the login process go through the Google Account service (and thus the cookies it uses for session tracking are not available to the individual app).

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