Add env variable alias compatibility warnings (#2044)

crates/config/README.md

@@ -32,6 +32,24 @@
 
 For comprehensive documentation, examples, and usage guides, please visit the main [RustFS repository](https://github.com/rustfs/rustfs).
 
+## Environment Variable Naming Conventions
+
+RustFS uses a flat naming style for top-level configuration: environment variables are `RUSTFS_*` without nested module segments.
+
+Examples:
+- `RUSTFS_REGION`
+- `RUSTFS_ADDRESS`
+- `RUSTFS_VOLUMES`
+- `RUSTFS_LICENSE`
+
+Current guidance:
+- Prefer module-specific names only when they are not top-level product configuration.
+- Renamed variables must keep backward-compatible aliases until before beta.
+- Alias usage must emit deprecation warnings and be treated as transitional only.
+- Deprecated example:
+  - `RUSTFS_ENABLE_SCANNER` -> `RUSTFS_SCANNER_ENABLED`
+  - `RUSTFS_ENABLE_HEAL` -> `RUSTFS_HEAL_ENABLED`
+
 ## 📄 License
 
 This project is licensed under the Apache License 2.0 - see the [LICENSE](../../LICENSE) file for details.

crates/config/src/constants/app.rs

@@ -128,6 +128,9 @@ pub const RUSTFS_LICENSE_URL: &str = "https://www.apache.org/licenses/LICENSE-2.
 /// Example: RUSTFS_ADDRESS=":9000"
 pub const ENV_RUSTFS_ADDRESS: &str = "RUSTFS_ADDRESS";
 
+/// Environment variable for server volumes.
+pub const ENV_RUSTFS_VOLUMES: &str = "RUSTFS_VOLUMES";
+
 /// Default port for rustfs
 /// This is the default port for rustfs.
 /// This is used to bind the server to a specific port.
@@ -153,6 +156,12 @@ pub const DEFAULT_CONSOLE_ADDRESS: &str = concat!(":", DEFAULT_CONSOLE_PORT);
 /// Default value: us-east-1
 pub const RUSTFS_REGION: &str = "us-east-1";
 
+/// Environment variable for server region.
+pub const ENV_RUSTFS_REGION: &str = "RUSTFS_REGION";
+
+/// Environment variable for server license.
+pub const ENV_RUSTFS_LICENSE: &str = "RUSTFS_LICENSE";
+
 /// Default log filename for rustfs
 /// This is the default log filename for rustfs.
 /// It is used to store the logs of the application.