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https://github.com/taylanbakircioglu/haproxy-openmanager.git
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Taylan Bakırcıoğlu
dbf5b8d688
CRITICAL FIX - No Agent Script Changes Required
PROBLEM IDENTIFIED:
- demo-agent1/agent3 sending malformed JSON
- Error: server_statuses: , (empty value before comma)
- Invalid JSON syntax causing HTTP 422 validation errors
- Agents stuck offline
ROOT CAUSE:
Agent daemon mode get_server_statuses() returns empty string when
HAProxy stats socket unavailable, resulting in: "server_statuses": ,
SOLUTION - BACKEND MIDDLEWARE (Production Safe):
Created JSONSanitizerMiddleware that automatically fixes common JSON
errors BEFORE FastAPI parses request body:
1. Empty values before comma/brace: field: , -> field: null,
2. Trailing commas: {field: value,} -> {field: value}
3. Only processes /api/agents/heartbeat endpoint
4. Logs what was fixed for auditing
BENEFITS:
- NO AGENT SCRIPT CHANGES (production safe)
- NO AGENT UPGRADE REQUIRED
- Backward compatible with all agent versions
- Zero impact on valid JSON
- Self-healing for future similar issues
- Detailed logging for monitoring
MIDDLEWARE ORDER:
PerformanceMonitoring -> RequestLogging -> JSONSanitizer -> ActivityLog -> CORS
HOW IT WORKS:
1. Intercepts POST /api/agents/heartbeat
2. Reads raw body before FastAPI
3. Applies regex fixes for known patterns
4. Replaces request body with sanitized version
5. FastAPI receives valid JSON
TESTING:
Before: {"server_statuses": ,"system_info": {...}}
After: {"server_statuses": null,"system_info": {...}}
Result: Pydantic validation passes, agent goes online
This middleware approach is MUCH safer than deploying agent script
changes to production servers.