wiki/reviews/20260111 doc_session_handling_analysis.md
2026-01-11 13:07:11 +01:00

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# Session Handling Analysis for Horizontal Scaling
## Executive Summary
**✅ YES, your application is STATELESS and ready for horizontal scaling with load balancers.**
The session handling architecture is designed to work across multiple gateway instances without requiring sticky sessions or shared in-memory storage. Users will **NOT** lose their sessions when API calls hit different gateway instances.
---
## Architecture Overview
### Backend Session Management (Gateway)
#### 1. **JWT Token-Based Authentication**
- **Location**: `gateway/modules/auth/authentication.py`
- **Token Storage**: JWT tokens are stored in **httpOnly cookies** (`auth_token` and `refresh_token`)
- **Token Format**: Self-contained JWT tokens with claims including:
- `sub` (username)
- `userId`
- `mandateId`
- `jti` (token ID)
- `sid` (session ID)
- `authenticationAuthority`
- `exp` (expiration)
#### 2. **Database-Backed Token Validation**
- **Location**: `gateway/modules/interfaces/interfaceDbAppObjects.py`
- **Token Table**: All tokens are stored in a `Token` database table with fields:
- `id` (jti - token ID)
- `userId`
- `authority`
- `sessionId`
- `mandateId`
- `status` (ACTIVE/REVOKED)
- `expiresAt`
- `revokedAt`, `revokedBy`, `reason`
- **Validation Process** (per request):
1. JWT token is extracted from httpOnly cookie or Authorization header
2. Token is decoded and validated (signature, expiration)
3. Token ID (`jti`) is extracted from the JWT payload
4. **Database query** is performed to verify:
- Token exists in database
- Token status is ACTIVE
- Token matches user, session, and mandate context
5. User is retrieved from database based on token claims
**Key Code Reference** (`gateway/modules/auth/authentication.py:141-191`):
```python
# For LOCAL gateway JWTs, enforce DB-backed token validity and revocation
if tokenId:
db_tokens = dbApp.getRecordset(Token, recordFilter={"id": tokenId})
if db_tokens:
db_token = db_tokens[0]
token_authority = str(db_token.get("authority", "")).lower()
if token_authority == str(AuthAuthority.LOCAL.value):
# Must be active and match user/session/mandate
active_token = appInterface.findActiveTokenById(
tokenId=tokenId,
userId=user.id,
authority=AuthAuthority.LOCAL,
sessionId=sessionId,
mandateId=str(mandateId) if mandateId else None,
)
if not active_token:
raise credentialsException
```
#### 3. **No In-Memory Session Storage**
-**No Redis** - No Redis or similar caching layer found
-**No Memcached** - No memcached usage found
-**No In-Memory Sessions** - All session state is in the database
-**Stateless Design** - Each request is independently validated
#### 4. **Session Management**
- **Session ID**: Generated on login (`uuid.uuid4()`) and stored in:
- JWT token claim (`sid`)
- Token database record (`sessionId`)
- **Logout**: Revokes all tokens for a session by updating database records (sets `status=REVOKED`)
- **Token Refresh**: Creates new tokens and stores them in database
**Key Code Reference** (`gateway/modules/routes/routeSecurityLocal.py:92-131`):
```python
# Create session id and include in token claims for session-scoped logout
session_id = str(uuid.uuid4())
token_data["sid"] = session_id
# Create access token + set cookie
access_token, _access_expires = createAccessToken(token_data)
setAccessTokenCookie(response, access_token)
# Save access token to database
token = Token(
id=jti,
userId=user.id,
authority=AuthAuthority.LOCAL,
tokenAccess=access_token,
tokenType="bearer",
expiresAt=expires_at.timestamp(),
sessionId=session_id,
mandateId=str(user.mandateId)
)
userInterface.saveAccessToken(token)
```
### Frontend Session Management
#### 1. **Cookie-Based Token Storage**
- **Location**: `frontend_agents/public/js/security/auth.js` and `frontend_agents/public/js/shared/apiCalls.js`
- **Storage Method**: Tokens are stored in **httpOnly cookies** (not localStorage or sessionStorage)
- **Automatic Transmission**: Cookies are automatically sent with requests using `credentials: 'include'`
**Key Code Reference** (`frontend_agents/public/js/shared/apiCalls.js:151-153`):
```javascript
// Note: With httpOnly cookies, we don't need to manually add Authorization header
// The browser automatically includes cookies with credentials: 'include'
```
#### 2. **CSRF Token Storage**
- **Location**: `sessionStorage` (client-side only)
- **Purpose**: CSRF protection, not session state
- **Note**: CSRF tokens can be regenerated if lost, so this doesn't affect session persistence
---
## Horizontal Scaling Compatibility
### ✅ **Fully Compatible - No Issues**
#### Why It Works:
1. **Stateless Backend**
- Each gateway instance validates tokens independently
- No shared in-memory state between instances
- All state is in the shared database
2. **Database as Single Source of Truth**
- Token validation queries the database on every request
- Token revocation updates the database
- All instances see the same token state
3. **Cookie-Based Tokens**
- Cookies are sent by the browser to whichever instance handles the request
- No server-side session storage needed
- Load balancer doesn't need sticky sessions
4. **JWT Self-Contained Claims**
- Token contains all necessary user context
- Database validation ensures token hasn't been revoked
- No need to look up session state from another instance
### Load Balancer Configuration
**Recommended Settings:**
-**Session Affinity**: **NOT REQUIRED** (can use round-robin or least-connections)
-**Health Checks**: Standard HTTP health checks
-**Cookie Handling**: No special configuration needed (browser handles cookies automatically)
### Potential Considerations
#### 1. **Database Connection Pooling**
- Ensure each gateway instance has proper database connection pooling
- Database should handle concurrent connections from multiple instances
- **Status**: ✅ Should work fine if database is configured for multiple connections
#### 2. **CSRF Token Regeneration**
- CSRF tokens stored in `sessionStorage` may be lost if user switches instances
- **Impact**: Minimal - CSRF tokens are regenerated automatically
- **Code Reference**: `frontend_agents/public/js/shared/apiCalls.js:186-203` handles CSRF token generation
#### 3. **Token Refresh Race Conditions**
- If multiple requests refresh tokens simultaneously, ensure database handles concurrent updates
- **Status**: ✅ Current implementation uses database transactions (via `saveAccessToken`)
#### 4. **Cookie Domain and Path**
- Ensure cookies are set with correct domain/path for load balancer
- **Current Settings** (`gateway/modules/auth/jwtService.py:58-66`):
- `path="/"`
- `samesite="strict"`
- `httponly=True`
- `secure` (based on HTTPS) ✅
---
## Testing Recommendations
### 1. **Multi-Instance Test**
- Deploy 2+ gateway instances behind a load balancer
- Login on one instance
- Make requests that hit different instances
- Verify session persists across instances
### 2. **Token Revocation Test**
- Login on instance A
- Logout on instance B
- Verify token is revoked (cannot make requests on instance A)
### 3. **Concurrent Request Test**
- Make multiple simultaneous requests
- Verify all requests succeed regardless of which instance handles them
### 4. **Database Connection Test**
- Monitor database connections from multiple instances
- Verify connection pooling works correctly
- Check for connection leaks
---
## Summary
| Aspect | Status | Notes |
|--------|--------|-------|
| **Stateless Backend** | ✅ YES | No in-memory session storage |
| **Database-Backed** | ✅ YES | All token state in database |
| **Cookie-Based** | ✅ YES | httpOnly cookies, auto-sent by browser |
| **Load Balancer Ready** | ✅ YES | No sticky sessions needed |
| **Horizontal Scaling** | ✅ READY | Can scale to multiple instances |
### Conclusion
**Your application is fully ready for horizontal scaling.** The session handling architecture is stateless and database-backed, which means:
1. ✅ Users will **NOT** lose sessions when requests hit different instances
2. ✅ Load balancer can use **round-robin** or **least-connections** (no sticky sessions needed)
3. ✅ Token validation works independently on each instance
4. ✅ Token revocation works across all instances (via database)
The only shared state is in the database, which you've confirmed will be a single logical instance. This is the correct architecture for horizontal scaling.
---
## Files Analyzed
### Backend
- `gateway/modules/auth/authentication.py` - Token validation
- `gateway/modules/auth/jwtService.py` - JWT creation and cookie management
- `gateway/modules/routes/routeSecurityLocal.py` - Login/logout endpoints
- `gateway/modules/interfaces/interfaceDbAppObjects.py` - Token database operations
- `gateway/modules/datamodels/datamodelSecurity.py` - Token data model
### Frontend
- `frontend_agents/public/js/security/auth.js` - Authentication logic
- `frontend_agents/public/js/shared/apiCalls.js` - API calls with cookie handling
---
*Analysis Date: 2025-01-27*
*Analyzed by: AI Assistant*