Nexus/server/api/health.py

"""Nexus — Health Check Endpoint
External monitoring endpoint for Shell health_monitor.sh and Supervisor.

Security: Only returns minimal status ("ok") for external probes.
Detailed health diagnostics require admin JWT auth via /health/detail.
"""

import logging

from fastapi import APIRouter, Depends
from fastapi.responses import PlainTextResponse
from sqlalchemy import text

from server.api.auth_jwt import require_current_admin
from server.domain.models import Admin
from server.infrastructure.database.session import AsyncSessionLocal
from server.infrastructure.redis.client import get_redis
from server.api.websocket import manager as ws_manager

logger = logging.getLogger("nexus.health")

router = APIRouter()


@router.get("/health", response_class=PlainTextResponse)
async def health_check():
    """Minimal health check — used by Shell health_monitor.sh (Layer 3 guardian).
    Returns plain-text "ok" — no JSON, no backend fingerprint.
    health_monitor.sh discards response body (curl -sf > /dev/null),
    so this is purely for HTTP status code.
    """
    return "ok"


@router.get("/health/detail")
async def health_detail(admin: Admin = Depends(require_current_admin)):
    """Detailed health diagnostics — requires admin JWT authentication.

    Returns Redis/MySQL/WebSocket status for admin dashboard use.
    """
    checks = {"python": "ok"}

    # Redis check
    try:
        redis = get_redis()
        await redis.ping()
        checks["redis"] = "ok"
    except Exception as e:
        logger.error(f"Redis health check failed: {e}")
        checks["redis"] = "unavailable"

    # MySQL check
    try:
        async with AsyncSessionLocal() as session:
            await session.execute(text("SELECT 1"))
        checks["mysql"] = "ok"
    except Exception as e:
        logger.error(f"MySQL health check failed: {e}")
        checks["mysql"] = "error"

    # WebSocket connections count
    try:
        checks["websocket_clients"] = await ws_manager.global_client_count()
    except Exception:
        checks["websocket_clients"] = ws_manager.client_count

    return {"status": "ok", "checks": checks}