Why do variables.env and configuration.py us different DNS names for the same services?

[freemansoft]

What are the DNS names for the redis and milvus server? They are referred to as localhost in some places and as redis and mivlus in others. They are pingable from traefic as redis and milvus

Redis

1. README.md redis://localhost:6379/0
2. variables.env redis://redis:6379/0
3. chain_server/configuration.py redis://localhost:6379/0
4. container name redis

Milvus

1. README.md http://localhost:19530
2. variables.env http://milvus:19530
3. chain_server/configuration.py http://localhost:19530
4. container name milvus