refactor: implement Redis singleton pattern for improved connection management; enhance graceful shutdown handling in bot

apps/bot/src/bot/features/download.ts

@@ -2,7 +2,7 @@
 import { type Context } from '../context';
 import { logHandle } from '../helpers/logging';
 import { TTL } from '@/config/redis';
-import { createRedisInstance } from '@/utils/redis';
+import { getRedisInstance } from '@/utils/redis';
 import { validateTikTokUrl } from '@/utils/urls';
 import { Downloader } from '@tobyg74/tiktok-api-dl';
 import { Composer, InputFile } from 'grammy';
@@ -11,7 +11,7 @@ const composer = new Composer<Context>();
 
 const feature = composer.chatType('private');
 
-const redis = createRedisInstance();
+const redis = getRedisInstance();
 
 feature.on('message:text', logHandle('download-message'), async (context) => {
   try {

apps/bot/src/index.ts

@@ -1,16 +1,37 @@
 import { createBot } from './bot';
 import { env as environment } from './config/env';
 import { logger } from './utils/logger';
+import { getRedisInstance } from './utils/redis';
 
 const bot = createBot({
   apiRoot: environment.TELEGRAM_API_ROOT,
   token: environment.BOT_TOKEN,
 });
 
+const redis = getRedisInstance();
+
+// Graceful shutdown function
+async function gracefulShutdown(signal: string) {
+  logger.info(`Received ${signal}, starting graceful shutdown...`);
+
+  try {
+    // Stop the bot
+    await bot.stop();
+    logger.info('Bot stopped');
+
+    // Disconnect Redis
+    redis.disconnect();
+    logger.info('Redis disconnected');
+  } catch (error) {
+    const err_ = error as Error;
+    logger.error('Error during graceful shutdown:' + err_.message || '');
+  }
+}
+
 // Stopping the bot when the Node.js process
 // is about to be terminated
-process.once('SIGINT', () => bot.stop());
+process.once('SIGINT', () => gracefulShutdown('SIGINT'));
-process.once('SIGTERM', () => bot.stop());
+process.once('SIGTERM', () => gracefulShutdown('SIGTERM'));
 
 bot.start({
   onStart: ({ username }) => logger.info(`Bot ${username} started`),

apps/bot/src/utils/redis.ts

@@ -2,7 +2,15 @@ import { env } from '@/config/env';
 import { logger } from '@/utils/logger';
 import Redis from 'ioredis';
 
-export function createRedisInstance() {
+const instance: Redis = createRedisInstance();
+
+export function getRedisInstance() {
+  if (!instance) return createRedisInstance();
+
+  return instance;
+}
+
+function createRedisInstance() {
   const redis = new Redis({
     host: env.REDIS_HOST,
     password: env.REDIS_PASSWORD,