Redis Scan Stream Node.js

scanStream.js

// Redis Client file

// const redis = require("redis");
// const { REDIS_HOST } = process.env;

// module.exports = () => {
// 	if (REDIS_HOST)
// 		return redis.createClient({
// 			url: `redis://${REDIS_HOST}:6379`
// 		});

// 	return redis.createClient();
// };

// scan stream tool
const { promisifyAll } = require("bluebird");
const redisClient = require("../lib/redisClient")();
const { promisify } = require("util");
const scanStream = promisify(redisClient.scan).bind(redisClient);
promisifyAll(redisClient);

// Recursive function to keep scanning
// pattern = commonKeyElement*.
// eg. - ltp_*
exports.scanAllKeys = async (pattern) => {
	const found = [];
	let cursor = "0";
	try {
		do {
			const reply = await scanStream(cursor, "MATCH", pattern, "COUNT", "10"); // scan 10 keys at once
			cursor = reply[0];
			// console.log("Cursor at: ", cursor);
			found.push(...reply[1]); // reply[1] is an array of matched keys.
		} while (cursor !== "0"); // cursor will be at 0 when scan completes
	} catch (error) {
		console.log("Redis scan error: ", error);
	}
	return found;
};