BE-11: Google OAuth Research (Authentication Flow)

[tecnodeveloper]

Description:
Research Google OAuth. Understand flow. Understand tokens. Understand how to connect frontend + backend. Also explore alternatives like Clerk and Better Auth. Goal → choose best auth system.

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User Story

Given authentication system not finalized
When I research OAuth and alternatives
Then I should be able to choose best auth approach

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Tasks

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Google OAuth Basics

1. Understand OAuth Concept

   • What is OAuth 2.0
   • Why use Google login
   • Benefits (no password handling)

2. Study OAuth Flow

   • User clicks "Login with Google"
   • Redirect to Google
   • User grants permission
   • Google returns token
   • Backend verifies token

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Google OAuth Implementation Research

3. Frontend Flow

   • Use Google login button
   • Get ID token
   • Send token to backend

4. Backend Flow (Flask/FastAPI)

   • Verify Google token
   • Extract user info (email, name)
   • Create user in MongoDB if not exists

5. Session Handling

   • Generate JWT after Google login
   • Maintain session

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Token Understanding

6. Learn Token Types

   • ID Token
   • Access Token
   • Refresh Token

7. Security Considerations

   • Token validation
   • Expiry handling
   • HTTPS requirement

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MongoDB Integration

8. User Storage

   • Store Google user in users collection
   • Save email + provider (google)
   • Avoid duplicate users

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**Postman Testing **

9. Test Backend Endpoint

   • Create /auth/google endpoint
   • Send token manually
   • Verify response

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Clerk Auth Research (Alternative)

10. Research Clerk

• What is Clerk
• Features (pre-built auth UI, OAuth support)
• Ease of integration with frontend

11. Evaluate Clerk Pros/Cons

• Easy setup
• Built-in UI
• Vendor lock-in

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Better Auth Research (Alternative)

12. Research Better Auth (Modern Auth Approach)

• What is Better Auth
• Self-hosted vs managed
• Flexibility

13. Compare with OAuth

• Control vs simplicity
• Customization level

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Other Alternatives

14. Research Other Auth Options

• Firebase Authentication
• Auth0
• Compare features

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Comparison & Decision

15. Compare All Options

• Google OAuth
• Clerk
• Better Auth
• Firebase/Auth0

16. Evaluate Based On

• Ease of use
• Security
• Scalability
• Integration with Flask/FastAPI
• Cost

17. Select Final Approach

• Choose best auth method
• Document reason

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Acceptance Criteria

• Google OAuth flow clearly understood
• Backend + frontend flow defined
• Clerk researched
• Better Auth researched
• Alternatives compared
• Final auth approach selected

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Testing Steps

1. Draw OAuth flow diagram
2. Test token verification logic
3. Try sample Google login (optional)
4. Compare with Clerk demo
5. Document findings

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Definition of Done

• Authentication approach finalized
• Clear implementation plan ready