Redis Connection Refused

running `yarn dev` getting error connection refused 

`Error: Redis connection to localhost:6379 failed - connect ECONNREFUSED 127.0.0.1:6379
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1056:14) {
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED',
  syscall: 'connect',
  address: '127.0.0.1',
  port: 6379`

What's it trying to connect to?