Deprecate and Remove Redundant Monitoring REST Endpoints #87

Parent Issue

Part of #80 - Epic: Consolidate All Monitoring Systems into Prometheus + Grafana

Current State

Multiple overlapping REST endpoints:

• GET /api/metrics/dashboard - Dashboard data
• GET /api/metrics/performance/summary - Performance summary
• GET /api/metrics/system/current - Current system metrics
• GET /api/monitoring/services/health - Service health
• GET /api/system/metrics - System metrics
• Plus WebSocket endpoints for real-time streaming

These endpoints duplicate data now available via Prometheus.

Goal

Gradually deprecate and remove redundant endpoints to eliminate duplicate metric collection.

Implementation

Phase 1: Mark as Deprecated (2 weeks)

Add deprecation warnings to responses:

@router.get("/dashboard", deprecated=True)
async def get_dashboard():
    return {
        "deprecated": True,
        "message": "Use Prometheus + Grafana for metrics. See /docs/monitoring/",
        "sunset_date": "2025-01-15",
        "data": ...
    }

Phase 2: Add Redirect Headers

response.headers["Deprecation"] = "true"
response.headers["Sunset"] = "Wed, 15 Jan 2025 00:00:00 GMT"
response.headers["Link"] = '</api/prometheus/metrics>; rel="successor-version"'

Phase 3: Remove Endpoints

After Grafana dashboards are complete and team is using them:

• Remove deprecated endpoints
• Update frontend to use Grafana embedded panels
• Delete in-memory metric stores

Endpoints to Deprecate

Keep These Endpoints

• /api/health - Quick liveness check (no metrics)
• /metrics - Prometheus scrape endpoint (canonical)
• /api/prometheus/metrics - Prometheus text format

Acceptance Criteria

• All redundant endpoints marked deprecated
• Deprecation warnings in API responses
• Sunset dates communicated to users
• Frontend updated to use Grafana
• Endpoints removed after sunset period
• No data loss during transition
• Documentation updated

Files to Modify

• backend/api/metrics.py - Add deprecation warnings
• backend/api/monitoring.py - Mark WebSocket deprecated
• backend/api/service_monitor.py - Redirect to Prometheus
• backend/api/system.py - Deprecate system metrics
• Frontend components to embed Grafana panels
• API documentation

Labels: deprecation, monitoring, cleanup