data provider: update internal caches if the data provider is shared

docs/full-configuration.md

@@ -202,6 +202,7 @@ The configuration file contains the following sections:
   - `update_mode`, integer. Defines how the database will be initialized/updated. 0 means automatically. 1 means manually using the initprovider sub-command.
   - `skip_natural_keys_validation`, boolean. If `true` you can use any UTF-8 character for natural keys as username, admin name, folder name. These keys are used in URIs for REST API and Web admin. If `false` only unreserved URI characters are allowed: ALPHA / DIGIT / "-" / "." / "_" / "~". Default: `false`.
   - `create_default_admin`, boolean. If enabled, a default admin user with username `admin` and password `password` will be created on first start. The default values can be overridden using the environment variables `SFTPGO_DEFAULT_ADMIN_USERNAME` and `SFTPGO_DEFAULT_ADMIN_PASSWORD`. You can also create the first admin user by using the web interface or by loading initial data. Default `false`.
+  - `is_shared`, integer. If the data provider is shared across multiple SFTPGo instances, set this parameter to `1`. `MySQL`, `PostgreSQL` and `CockroachDB` can be shared, this setting is ignored for other data providers. For shared data providers, SFTPGo periodically reloads the latest updated users, based on the `updated_at` field, and updates its internal caches if users are updated from a different instance. This check, if enabled, is executed every 10 minutes. Default: `0`.
 - **"httpd"**, the configuration for the HTTP server used to serve REST API and to expose the built-in web interface
   - `bindings`, list of structs. Each struct has the following fields:
     - `port`, integer. The port used for serving HTTP requests. Default: 8080.