Автоматично повідомляй команду про наявність звʼязку за допомогою Firebase

monitor_online_status.ts

// 1. Set up Firebase app
// 2. Set up Slack webhook
// 3. Configure slack.webhook_url in the app
// 4. Deploy functions
// 5. Note the `canary` function URL
// 6. Make sure to GET the `canary` endpoint once an hour.
// 7. That's all!

import * as admin from "firebase-admin";
import * as functions from "firebase-functions";
import fetch from "node-fetch";

admin.initializeApp();

function notifySlack(text: string) {
  const slackWebhookURL = functions.config().slack.webhook_url;

  const request = {
    text,
  };

  return fetch(slackWebhookURL, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify(request),
  });
}

export const monitor = functions.pubsub
  .schedule("1 9-19 * * 1-5")
  .timeZone("Europe/Kiev")
  .onRun(async () => {
    const docRef = admin.firestore().doc("online/status");
    const stats = await docRef.get();
    const data = stats.data() as {
      online: number;
      offline: number;
      backOnline: number;
    };

    if (!data.online) {
      return;
    }

    const now = Date.now();
    const isOnline = now - data.online < 3660 * 1000;

    if (isOnline) {
      if (!data.backOnline || data.backOnline < data.offline) {
        await docRef.update({ backOnline: now });
        return notifySlack(
          ":full_moon_with_face: network is back online"
        );
      }
    } else {
      if (!data.offline || data.offline < data.online) {
        await docRef.update({ offline: now });
        return notifySlack(
          ":dark_moon_with_face: network is offline"
        );
      }
    }
    return "all good";
  });

export const canary = functions.https.onRequest(
  async (_, response) => {
    const docRef = admin.firestore().doc("online/status");
    try {
      await docRef.update({ online: Date.now() });
    } catch {
      await docRef.create({ online: Date.now() });
    }
    response.send("acknowledged");
  }
);