72 lines
2.5 KiB
Python
72 lines
2.5 KiB
Python
from __future__ import annotations
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import asyncio
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import logging
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import socket
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from sqlalchemy import select
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from sqlalchemy.ext.asyncio import AsyncSession
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from roundtable.core.alerts import record_metric
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from roundtable.models.hosts import Host
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from roundtable.models.monitors import DnsResult, DnsStatus
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logger = logging.getLogger(__name__)
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async def dns_check(host: Host, session: AsyncSession) -> None:
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"""Resolve host and write dns_result + metrics."""
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result = await _resolve(host.address)
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if result["resolved"]:
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resolved_ip = result["ip"] # first A/AAAA record (stored in DB)
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all_ips = result["all_ips"]
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# Check against expected IP: pass only if at least one returned record matches
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if host.dns_expected_ip and host.dns_expected_ip not in all_ips:
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status = DnsStatus.failed
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dns_resolved_metric = 0.0
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else:
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status = DnsStatus.resolved
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dns_resolved_metric = 1.0
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# Detect IP change vs most recent successful resolution
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prev_result = await session.execute(
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select(DnsResult)
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.where(DnsResult.host_id == host.id, DnsResult.status == DnsStatus.resolved)
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.order_by(DnsResult.resolved_at.desc())
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.limit(1)
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)
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prev = prev_result.scalar_one_or_none()
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ip_changed = 1.0 if (prev and prev.resolved_ip != resolved_ip) else 0.0
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else:
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resolved_ip = None
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status = DnsStatus.failed
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dns_resolved_metric = 0.0
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ip_changed = 0.0
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session.add(DnsResult(
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host_id=host.id,
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status=status,
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resolved_ip=resolved_ip,
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))
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await session.flush()
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await record_metric(session, "dns", host.name, "resolved", dns_resolved_metric)
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await record_metric(session, "dns", host.name, "ip_changed", ip_changed)
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async def _resolve(address: str) -> dict:
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"""Resolve hostname. Returns all A/AAAA records; stores first as resolved_ip."""
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try:
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loop = asyncio.get_running_loop()
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infos = await loop.run_in_executor(
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None, socket.getaddrinfo, address, None, socket.AF_UNSPEC, socket.SOCK_STREAM
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)
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if infos:
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all_ips = [info[4][0] for info in infos]
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return {"resolved": True, "ip": all_ips[0], "all_ips": all_ips}
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return {"resolved": False, "ip": None, "all_ips": []}
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except Exception as exc:
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logger.debug(f"DNS resolution failed for {address}: {exc}")
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return {"resolved": False, "ip": None, "all_ips": []}
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