I've implemented Google oauth login based on this tutorial: https://www.callicoder.com/spring-boot-security-oauth2-social-login-part-1/
It is working correctly when app is run locally. However, after deploying it on GKE, I'm unable to log in - flow fails with the following error:
error: [invalid_token_response] An error occurred while attempting to retrieve the OAuth 2.0 Access Token Response: I/O error on POST request for "https://www.googleapis.com/oauth2/v4/token": www.googleapis.com; nested exception is java.net.UnknownHostException: www.googleapis.comWhich comes from OAuth2AccessTokenResponseClient
As I said before, it's working fine when run on localhost and I'm unable to debug it. The app is deployed with Ingress using a static IP. I've assigned that IP to my domain very recently. Domain is registered in Google APIs Authorised redirect URIs
The problem was that kube-dns pods dind't get up. I set up a preemptible cluster and added a taint to it's only node pool. That prevented kube-dns from starting:
Normal NotTriggerScaleUp 61s (x22798 over 2d18h) cluster-autoscaler pod didn't trigger scale-up (it wouldn't fit if a new node is added): 1 node(s) had taints that the pod didn't tolerate
Warning FailedScheduling 44s (x141 over 26h) default-scheduler 0/1 nodes are available: 1 node(s) had taints that the pod didn't tolerate.After removing the taint hostname got resolved
Google APIs use the OAuth 2.0 protocol for authentication and authorization. Google supports common OAuth 2.0 scenarios such as those for web server, installed, and client-side applications. Please have a look at this link.
We can follow the below steps for obtaining OAuth 2.0 access tokens. Step 1: Generate a code verifier and challenge Step 2: Send a request to Google's OAuth 2.0 server Step 3: Google prompts user for consent Step 4: Handle the OAuth 2.0 server response Step 5: Exchange authorization code for refresh and access tokens