An ensemble is a multi-service stack declared once and brought up together — web, database, cache, workers — with stable aliases instead of hunting IP addresses.
Why ensembles
- One unit of work — start, stop, and inspect the whole application stack.
- Service aliases — containers resolve each other by name inside the ensemble.
- Volume and port wiring — persistence and published ports live next to the services that need them.
A familiar pattern
Think of a WordPress blog with MariaDB and a cache: three services, shared network names, mounts for uploads and database files. That is an ensemble. Scale-out and HA demos reuse the same idea across nodes.