[keyserver] Introduce cronjob for product metrics

Summary: This cronjob will generate some product metrics daily and send them to me in a Comm chat.

Test Plan: Ran it via script on the auxiliary production keyserver instance running on my personal server and confirmed that it works

Reviewers: will, varun

Reviewed By: will

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D13751

keyserver/src/cron/cron.js

@@ -6,6 +6,7 @@ import schedule from 'node-schedule';
 
 import { backupDB } from './backups.js';
 import { createDailyUpdatesThread } from './daily-updates.js';
+import { postMetrics } from './metrics.js';
 import { postLeaderboard } from './phab-leaderboard.js';
 import { updateAndReloadGeoipDB } from './update-geoip-db.js';
 import { updateIdentityReservedUsernames } from './update-identity-reserved-usernames.js';
@@ -164,5 +165,18 @@ if (cluster.isMaster) {
         }
       },
     );
+    schedule.scheduleJob(
+      '0 6 * * *', // every day at 6:00 AM in the keyserver's timezone
+      async () => {
+        try {
+          await postMetrics();
+        } catch (e) {
+          console.warn(
+            'encountered error while trying to post product metrics',
+            e,
+          );
+        }
+      },
+    );
   }
 }

keyserver/src/cron/metrics.js

@@ -0,0 +1,127 @@
+// @flow
+
+import bots from 'lib/facts/bots.js';
+import { messageTypes } from 'lib/types/message-types-enum.js';
+
+import createMessages from '../creators/message-creator.js';
+import { dbQuery, SQL } from '../database/database.js';
+import { createScriptViewer } from '../session/scripts.js';
+
+const metricsChannel = '80820870';
+const millisecondsPerDay = 24 * 60 * 60 * 1000;
+
+async function postMetrics() {
+  if (!process.env.RUN_COMM_TEAM_DEV_SCRIPTS) {
+    // This is a job that the Comm internal team uses
+    return;
+  }
+
+  const oneDayAgo = Date.now() - millisecondsPerDay;
+  const thirtyDaysAgo = Date.now() - millisecondsPerDay * 30;
+  const [
+    dailyActives,
+    monthlyActives,
+    oneWeekRetention,
+    twoWeekRetention,
+    retentionSinceLaunch,
+  ] = await Promise.all([
+    getActiveCountSince(oneDayAgo),
+    getActiveCountSince(thirtyDaysAgo),
+    getRetention(7),
+    getRetention(14),
+    getRetentionSinceLaunch(),
+  ]);
+
+  const metrics = {
+    'DAUs': dailyActives,
+    'MAUs': monthlyActives,
+    'D7': oneWeekRetention,
+    'D14': twoWeekRetention,
+    'retention since launch': retentionSinceLaunch,
+  };
+  const today = new Date().toLocaleString('default', {
+    day: 'numeric',
+    month: 'long',
+    year: 'numeric',
+  });
+  const metricText =
+    `### Metrics for ${today}\n` +
+    '```\n' +
+    `${JSON.stringify(metrics, undefined, 2)}\n` +
+    '```';
+
+  const viewer = createScriptViewer(bots.commbot.userID);
+  const messageDatas = [
+    {
+      type: messageTypes.TEXT,
+      threadID: metricsChannel,
+      creatorID: bots.commbot.userID,
+      time: Date.now(),
+      text: metricText,
+    },
+  ];
+  await createMessages(viewer, messageDatas);
+}
+
+async function getActiveCountSince(time: number): Promise<number> {
+  const [result] = await dbQuery(SQL`
+    SELECT COUNT(DISTINCT u.id) AS count
+    FROM users u
+    LEFT JOIN cookies c ON c.user = u.id
+    WHERE last_used IS NOT NULL AND last_used > ${time}
+  `);
+  const [row] = result;
+  return row.count;
+}
+
+// Of the users that created their account N days ago,
+// how many were active in the last day?
+type RetentionResult = { +retainedCount: number, +totalCount: number };
+async function getRetention(daysAgo: number): Promise<RetentionResult> {
+  const startOfNDaysAgo = Date.now() - millisecondsPerDay * daysAgo;
+  const endOfNDaysAgo = Date.now() - millisecondsPerDay * (daysAgo - 1);
+  const [result] = await dbQuery(SQL`
+    SELECT u.id, MAX(c.last_used) AS lastUsed
+    FROM users u
+    LEFT JOIN cookies c ON c.user = u.id
+    WHERE u.creation_time >= ${startOfNDaysAgo}
+      AND u.creation_time < ${endOfNDaysAgo}
+    GROUP BY u.id
+  `);
+
+  const totalCount = result.length;
+
+  const oneDayAgo = Date.now() - millisecondsPerDay;
+  const retainedCount = result.filter(
+    ({ lastUsed }) => lastUsed > oneDayAgo,
+  ).length;
+
+  return { retainedCount, totalCount };
+}
+
+// We're measuring users that signed up in the 7 days following launch.
+// They count as retained if they've used Comm in the last day.
+async function getRetentionSinceLaunch(): Promise<RetentionResult> {
+  const launchDate = new Date('2024-10-03');
+  const launchDaysAgo = Math.ceil(
+    (Date.now() - launchDate.getTime()) / millisecondsPerDay,
+  );
+
+  const retentionPromises: Array<Promise<RetentionResult>> = [];
+  for (let i = 0; i < 7; i++) {
+    retentionPromises.push(getRetention(launchDaysAgo - i));
+  }
+
+  const totalRetentionResults = {
+    retainedCount: 0,
+    totalCount: 0,
+  };
+  const retentionResults = await Promise.all(retentionPromises);
+  for (const retentionResult of retentionResults) {
+    totalRetentionResults.retainedCount += retentionResult.retainedCount;
+    totalRetentionResults.totalCount += retentionResult.totalCount;
+  }
+  return totalRetentionResults;
+}
+
+export { postMetrics };