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Cache & Pub/Sub Redis Integration

This document provides instructions for setting up Redis-based caching and pub/sub in the ConvoStack backend system. Redis is an optional component that can be used to enhance the performance and scalability of the system.

We strongly recommend using Redis for any production ConvoStack deployment. It is a must-have in any case where multiple instances of ConvoStack are being operated concurrently on the same database to ensure that messages are properly streamed to clients.

Prerequisites​

Before proceeding with the Redis integration, make sure you have the following prerequisites:

  • Redis server installed and running.
  • Redis URL or connection information.

Installation​

To use Redis-based caching and pub/sub in the ConvoStack backend, follow these steps:

  1. Install the required dependencies:
npm install redis ioredis graphql-redis-subscriptions
  1. Import the necessary modules in your code:
import Redis from 'ioredis';
import {RedisPubSub} from 'graphql-redis-subscriptions';
  1. Set up Redis caching and pub/sub using the provided Redis URL or connection information. Update your code snippet accordingly:
// Create Redis client
export const createRedisInstance = (url: string) => {
   // Create a new Redis instance
   const redis = new Redis(url);

   // Related to Upstash issue https://community.fly.io/t/upstash-redis-not-reachable-sometimes/9993
   // and https://community.fly.io/t/upstash-redis-and-could-not-send-http-request-to-instance-connection-error-timed-out-logs/10104
   // Send a PING command every minute
   setInterval(() => {
      redis.ping((error, result) => {
         if (error) {
            console.error('Error sending Redis PING command:', error);
         } else {
            console.log('Received Redis PONG:', result);
         }
      });
   }, 60 * 1000);

   return redis;
}

// Setup Redis-based caching and pub/sub if we set the REDIS_URL env var
const convEventsOpts = {} as IConversationEventServiceOptions;
if (process.env.REDIS_URL) {
   convEventsOpts.pubSubEngine = new RedisPubSub({
      subscriber: createRedisInstance(process.env.REDIS_URL),
      publisher: createRedisInstance(process.env.REDIS_URL),
      connectionListener: (err) => {
         console.error(`Redis pub/sub engine error: ${err}`);
      }
   });
   convEventsOpts.cache = createRedisInstance(process.env.REDIS_URL);
}

Make sure to set the REDIS_URL env var with your Redis URL.

  1. Initialize the ConvoStack backend with the configured Redis cache and pub/sub:
const backend = new ConvoStackBackendExpress({
    conversationEventServiceOptions: convEventsOpts,
    // ...
});