I need help, im confused with the documentation.

I have 2 redis server running. 1 for dev and 1 for production. Also I have 2 apis 1 for dev and 1 for production.

now, i want to

api dev - connect to redis dev env
api prod - connect to redis prod env

Based from docs[https://docs.railway.app/guides/variables#referencing-another-services-variable] I can use reference variable.

My question is that, how will i know that when i use Redis.REDISHOSTRedis.REDISPASSWORD etc… it will use the correct Redis service env

Redis ProjectID: ec7a6b3f-46c6-4337-a5f5-60c433fe477c/service/3579cf7f-6608-4ec1-aece-88cb82fc989d
Nodejs/NestJs ProjectID: d85df9df-e8f2-42e7-81ea-4e1929823be4