⭐ Environment Variable Strategy

Each StartAction injects a required set of engine-specific environment variables automatically, plus any user-provided runtime variables it doesn't already see a matching key for. Naming follows each engine's own real prefix — MARIADB_* is genuinely distinct from MYSQL_*, not an alias.

The real per-engine required variables, confirmed directly against source, are on the env-vars-and-volumes.html, alongside Persistent Volumes.