overleaf/services/real-time/app/js/RedisClientManager.js

const redis = require('redis-sharelatex')
const logger = require('logger-sharelatex')

module.exports = {
  createClientList(...configs) {
    // create a dynamic list of redis clients, excluding any configurations which are not defined
    return configs.filter(Boolean).map((x) => {
      const redisType = x.cluster
        ? 'cluster'
        : x.sentinels
        ? 'sentinel'
        : x.host
        ? 'single'
        : 'unknown'
      logger.log({ redis: redisType }, 'creating redis client')
      return redis.createClient(x)
    })
  }
}