Files
DECNET/decnet/web/router/health/api_get_health.py
anti 931f33fb06 perf: cache Docker daemon ping in /health (5s TTL)
Creating a new docker.from_env() client per /health request opened a
fresh unix-socket connection each time. Under load that's wasteful and
hammers dockerd.

Keep a module-level client + last-check timestamp; actually ping every
5 seconds, return cached state in between. Reset helper provided for
tests.
2026-04-17 15:01:53 -04:00

113 lines
3.7 KiB
Python

import time
from typing import Any, Optional
from fastapi import APIRouter, Depends
from fastapi.responses import JSONResponse
from decnet.telemetry import traced as _traced
from decnet.web.dependencies import require_viewer, repo
from decnet.web.db.models import HealthResponse, ComponentHealth
router = APIRouter()
_OPTIONAL_SERVICES = {"sniffer_worker"}
# Cache Docker client and health result to avoid hammering the Docker socket
_docker_client: Optional[Any] = None
_docker_healthy: bool = False
_docker_detail: str = ""
_docker_last_check: float = 0.0
_DOCKER_CHECK_INTERVAL = 5.0 # seconds between actual Docker pings
def _reset_docker_cache() -> None:
"""Reset cached Docker state — used by tests."""
global _docker_client, _docker_healthy, _docker_detail, _docker_last_check
_docker_client = None
_docker_healthy = False
_docker_detail = ""
_docker_last_check = 0.0
@router.get(
"/health",
response_model=HealthResponse,
tags=["Observability"],
responses={
401: {"description": "Could not validate credentials"},
403: {"description": "Insufficient permissions"},
503: {"model": HealthResponse, "description": "System unhealthy"},
},
)
@_traced("api.get_health")
async def get_health(user: dict = Depends(require_viewer)) -> Any:
components: dict[str, ComponentHealth] = {}
# 1. Database
try:
await repo.get_total_logs()
components["database"] = ComponentHealth(status="ok")
except Exception as exc:
components["database"] = ComponentHealth(status="failing", detail=str(exc))
# 2. Background workers
from decnet.web.api import get_background_tasks
for name, task in get_background_tasks().items():
if task is None:
components[name] = ComponentHealth(status="failing", detail="not started")
elif task.done():
if task.cancelled():
detail = "cancelled"
else:
exc = task.exception()
detail = f"exited: {exc}" if exc else "exited unexpectedly"
components[name] = ComponentHealth(status="failing", detail=detail)
else:
components[name] = ComponentHealth(status="ok")
# 3. Docker daemon (cached — avoids creating a new client per request)
global _docker_client, _docker_healthy, _docker_detail, _docker_last_check
now = time.monotonic()
if now - _docker_last_check > _DOCKER_CHECK_INTERVAL:
try:
import docker
if _docker_client is None:
_docker_client = docker.from_env()
_docker_client.ping()
_docker_healthy = True
_docker_detail = ""
except Exception as exc:
_docker_client = None
_docker_healthy = False
_docker_detail = str(exc)
_docker_last_check = now
if _docker_healthy:
components["docker"] = ComponentHealth(status="ok")
else:
components["docker"] = ComponentHealth(status="failing", detail=_docker_detail)
# Compute overall status
required_failing = any(
c.status == "failing"
for name, c in components.items()
if name not in _OPTIONAL_SERVICES
)
optional_failing = any(
c.status == "failing"
for name, c in components.items()
if name in _OPTIONAL_SERVICES
)
if required_failing:
overall = "unhealthy"
elif optional_failing:
overall = "degraded"
else:
overall = "healthy"
result = HealthResponse(status=overall, components=components)
status_code = 503 if overall == "unhealthy" else 200
return JSONResponse(content=result.model_dump(), status_code=status_code)