Database setup for the Website service (#13)

This PR contains the work done to introduce a _Fluent_-based persistence layer for the Website service, selectable at runtime alongside the existing in-memory default, plus the local dev tooling and docs to support it.

To provide further details about the work:

* Persistence package
  * The `Driver` and `TLS` enumerations
  * The `Configuration` type
  * The `Service` factory that builds the  service
  * `PrepareDB` for migrations registration
  * The `Probe` for readiness checks.

* App integration
  *  Builds the driver, registers migrations, and attaches `Fluent` to the service lifecycle so it starts/stops with the HTTP server.
  * Migrate-on-boot is gated to the in-memory backend; MySQL/MariaDB is migrated out of band via --database-migrate so shared databases never race on startup.
  * The `ConfigReader+Properties` extension maps database.* config keys onto the driver.

* Library
  * Added database configuration constants.
  * The `HealthController` controller gains a readiness probe: `GET /health/ready` checks whether the database is reachable, separate from the existing liveness check.

* Others
  * Updated the `docker-compose` files to support a database service behind a database profile, and hardened for local development
  * New database targets on the `Makefile` file and overall documentation updated
  * Updated the `.env.local`, `Dockerfile`, and `README` files to document the persistence workflow, config keys, and local DB commands

Reviewed-on: rock-n-code/loud-amsterdam#13
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Services/Website/Sources/Library/Public/Extensions/AbsoluteConfigKey+Constants.swift

@@ -15,6 +15,27 @@ extension AbsoluteConfigKey {
         /// The absolute configuration key for the minimum response body size, in bytes, before compression is applied.
         public static let minResponseSize: AbsoluteConfigKey = .init(.Compression.minResponseSize)
     }
+    /// A namespace for the persistence configuration keys, as absolute keys.
+    public enum Database {
+        /// The absolute configuration key selecting migrate-and-exit mode.
+        public static let migrate: AbsoluteConfigKey = .init(.Database.migrate)
+        /// The absolute configuration key for the persistence driver.
+        public static let driver: AbsoluteConfigKey = .init(.Database.driver)
+        /// The absolute configuration key for the MySQL/MariaDB host.
+        public static let host: AbsoluteConfigKey = .init(.Database.host)
+        /// The absolute configuration key for the MySQL/MariaDB port.
+        public static let port: AbsoluteConfigKey = .init(.Database.port)
+        /// The absolute configuration key for the database name.
+        public static let name: AbsoluteConfigKey = .init(.Database.name)
+        /// The absolute configuration key for the database username.
+        public static let username: AbsoluteConfigKey = .init(.Database.username)
+        /// The absolute configuration key for the database password.
+        public static let password: AbsoluteConfigKey = .init(.Database.password)
+        /// The absolute configuration key for the TLS posture used when connecting.
+        public static let tls: AbsoluteConfigKey = .init(.Database.tls)
+        /// The absolute configuration key for the maximum pooled connections per event loop.
+        public static let poolMaxPerEventLoop: AbsoluteConfigKey = .init(.Database.poolMaxPerEventLoop)
+    }
     /// A namespace for the HTTP server configuration keys, as absolute keys.
     public enum HTTP {
         /// The absolute configuration key for the host the server binds to.

Services/Website/Sources/Library/Public/Extensions/ConfigKey+Constants.swift

@@ -15,6 +15,27 @@ extension ConfigKey {
         /// The configuration key for the minimum response body size, in bytes, before compression is applied.
         public static let minResponseSize: ConfigKey = "compression.minimumResponseSize"
     }
+    /// A namespace for the persistence configuration keys.
+    public enum Database {
+        /// The configuration key selecting migrate-and-exit mode (run migrations, then exit) instead of serving.
+        public static let migrate: ConfigKey = "database.migrate"
+        /// The configuration key for the persistence driver (`inMemory` or `mysql`).
+        public static let driver: ConfigKey = "database.driver"
+        /// The configuration key for the MySQL/MariaDB host.
+        public static let host: ConfigKey = "database.host"
+        /// The configuration key for the MySQL/MariaDB port.
+        public static let port: ConfigKey = "database.port"
+        /// The configuration key for the database name.
+        public static let name: ConfigKey = "database.name"
+        /// The configuration key for the database username.
+        public static let username: ConfigKey = "database.username"
+        /// The configuration key for the database password.
+        public static let password: ConfigKey = "database.password"
+        /// The configuration key for the TLS posture used when connecting (`off`, `prefer`, or `require`).
+        public static let tls: ConfigKey = "database.tls"
+        /// The configuration key for the maximum pooled connections per event loop.
+        public static let poolMaxPerEventLoop: ConfigKey = "database.pool.maxPerEventLoop"
+    }
     /// A namespace for the HTTP server configuration keys.
     public enum HTTP {
         /// The configuration key for the host the server binds to.

Services/Website/Sources/Library/Public/Extensions/Int+Constants.swift

@@ -13,4 +13,11 @@ extension Int {
         /// The default minimum response body size, in bytes, before compression is applied (1 KB).
         public static let minResponseSize = 1_024
     }
+    /// A namespace for the persistence's default configuration values.
+    public enum Database {
+        /// The default MySQL/MariaDB port.
+        public static let port = 3_306
+        /// The default maximum pooled connections per event loop.
+        public static let poolMaxPerEventLoop = 4
+    }
 }

Services/Website/Sources/Library/Public/Extensions/String+Constants.swift

@@ -1,4 +1,23 @@
 extension String {
+    /// A namespace for the persistence's default configuration values and recognized tokens.
+    public enum Database {
+        /// The default persistence driver: in-memory SQLite, which needs no external infrastructure.
+        public static let driver = "inMemory"
+        /// The driver token selecting the MySQL/MariaDB backend.
+        public static let driverMySQL = "mysql"
+        /// The default MySQL/MariaDB host.
+        public static let host = "localhost"
+        /// The default database name.
+        public static let name = "loud"
+        /// The default database username.
+        public static let username = "loud"
+        /// The default TLS posture token.
+        public static let tls = "prefer"
+        /// The TLS token disabling TLS.
+        public static let tlsOff = "off"
+        /// The TLS token requiring TLS.
+        public static let tlsRequire = "require"
+    }
     /// A namespace for well-known path string constants.
     public enum Path {
         /// The directory, relative to the working directory, that the website's static files are served from.