matrix-alertbot/matrix_alertbot/webhook.py

from __future__ import annotations

import logging

import prometheus_client
from aiohttp import ClientError, web, web_request
from aiohttp_prometheus_exporter.handler import metrics
from aiohttp_prometheus_exporter.middleware import prometheus_middleware_factory
from diskcache import Cache
from nio import AsyncClient, LocalProtocolError

from matrix_alertbot.alert import Alert, AlertRenderer
from matrix_alertbot.chat_functions import send_text_to_room
from matrix_alertbot.config import Config

logger = logging.getLogger(__name__)

routes = web.RouteTableDef()


@routes.get("/health")
async def get_health(request: web_request.Request) -> web.Response:
    return web.Response(status=200)


@routes.post("/alerts/{room_id}")
async def create_alerts(request: web_request.Request) -> web.Response:
    data = await request.json()
    room_id = request.match_info["room_id"]

    client: AsyncClient = request.app["client"]
    config: Config = request.app["config"]
    cache: Cache = request.app["cache"]
    alert_renderer: AlertRenderer = request.app["alert_renderer"]

    if room_id not in config.allowed_rooms:
        logger.error("Cannot send alerts to room ID {room_id}.")
        return web.Response(
            status=401, body=f"Cannot send alerts to room ID {room_id}."
        )

    if "alerts" not in data:
        logger.error("Received data without 'alerts' key")
        return web.Response(status=400, body="Data must contain 'alerts' key.")

    alerts = data["alerts"]

    if not isinstance(data["alerts"], list):
        alerts_type = type(alerts).__name__
        logger.error(f"Received data with invalid alerts type '{alerts_type}'.")
        return web.Response(
            status=400, body=f"Alerts must be a list, got '{alerts_type}'."
        )

    logger.info(f"Received {len(alerts)} alerts for room ID {room_id}: {data}")

    if len(data["alerts"]) == 0:
        return web.Response(status=400, body="Alerts cannot be empty.")

    for alert in alerts:
        try:
            alert = Alert.from_dict(alert)
        except KeyError as e:
            logger.error(f"Cannot parse alert dict: {e}")
            return web.Response(status=400, body=f"Invalid alert: {alert}.")

        plaintext = alert_renderer.render(alert, html=False)
        html = alert_renderer.render(alert, html=True)

        try:
            event = await send_text_to_room(
                client, room_id, plaintext, html, notice=False
            )
        except (LocalProtocolError, ClientError) as e:
            logger.error(
                f"Unable to send alert {alert.fingerprint} to Matrix room: {e}"
            )
            return web.Response(
                status=500,
                body=f"An error occured when sending alert with fingerprint '{alert.fingerprint}' to Matrix room.",
            )

        if alert.firing:
            cache.set(
                event.event_id, alert.fingerprint, expire=config.cache_expire_time
            )

    return web.Response(status=200)


class Webhook:
    def __init__(self, client: AsyncClient, cache: Cache, config: Config) -> None:
        self.app = web.Application(logger=logger)
        self.app["client"] = client
        self.app["config"] = config
        self.app["cache"] = cache
        self.app["alert_renderer"] = AlertRenderer(config.template_dir)
        self.app.add_routes(routes)

        prometheus_registry = prometheus_client.CollectorRegistry(auto_describe=True)
        self.app.middlewares.append(
            prometheus_middleware_factory(registry=prometheus_registry)
        )
        self.app.router.add_get("/metrics", metrics())

        self.runner = web.AppRunner(self.app)

        self.config = config
        self.address = config.address
        self.port = config.port
        self.socket = config.socket

    async def start(self) -> None:
        await self.runner.setup()

        site: web.BaseSite
        if self.address and self.port:
            site = web.TCPSite(self.runner, self.address, self.port)
            logger.info(f"Listening on {self.address}:{self.port}")
        elif self.socket:
            site = web.UnixSite(self.runner, self.socket)
            logger.info(f"Listening on unix://{self.socket}")

        await site.start()

    async def close(self) -> None:
        await self.runner.cleanup()