Updated the ConfigReader+Properties extension in the Website service target to fail to the boot in case of unknown database tokens.

Services/Website/Sources/App/Extensions/ConfigReader+Properties.swift

@@ -108,48 +108,53 @@ package extension ConfigReader {
     ///
     /// When `database.driver` selects PostgreSQL, the connection parameters are assembled from the `database.host`, `database.port`,
     /// `database.name`, `database.username`, `database.password` (empty when unset), `database.tls`,
-    /// `database.pool.maxPerEventLoop`, and `database.pool.timeout` keys. Any other driver value falls back to the in-memory database.
+    /// `database.pool.maxPerEventLoop`, and `database.pool.timeout` keys. Any token but `inMemory` and `postgres` throws a
+    /// ``ConfigError``: a mistyped driver fails the boot rather than running on the in-memory database and discarding every write on restart.
     var driver: Driver {
-        switch string(
-            forKey: .Database.driver,
-            default: .Database.driver
-        ) {
-        case .Database.driverPostgres:
-            return .postgres(
-                .init(
-                    host: string(
-                        forKey: .Database.host,
-                        default: .Database.host
-                    ),
-                    port: int(
-                        forKey: .Database.port,
-                        default: .Database.port
-                    ),
-                    name: string(
-                        forKey: .Database.name,
-                        default: .Database.name
-                    ),
-                    username: string(
-                        forKey: .Database.username,
-                        default: .Database.username
-                    ),
-                    password: string(
-                        forKey: .Database.password,
-                        default: ""
-                    ),
-                    tls: tls,
-                    maxConnectionsPerEventLoop: int(
-                        forKey: .Database.poolMaxPerEventLoop,
-                        default: .Database.poolMaxPerEventLoop
-                    ),
-                    poolTimeout: .seconds(int(
-                        forKey: .Database.poolTimeout,
-                        default: .Database.poolTimeout
-                    ))
+        get throws {
+            switch string(
+                forKey: .Database.driver,
+                default: .Database.driver
+            ) {
+            case .Database.driverInMemory:
+                return .inMemory
+            case .Database.driverPostgres:
+                return .postgres(
+                    .init(
+                        host: string(
+                            forKey: .Database.host,
+                            default: .Database.host
+                        ),
+                        port: int(
+                            forKey: .Database.port,
+                            default: .Database.port
+                        ),
+                        name: string(
+                            forKey: .Database.name,
+                            default: .Database.name
+                        ),
+                        username: string(
+                            forKey: .Database.username,
+                            default: .Database.username
+                        ),
+                        password: string(
+                            forKey: .Database.password,
+                            default: ""
+                        ),
+                        tls: try tls,
+                        maxConnectionsPerEventLoop: int(
+                            forKey: .Database.poolMaxPerEventLoop,
+                            default: .Database.poolMaxPerEventLoop
+                        ),
+                        poolTimeout: .seconds(int(
+                            forKey: .Database.poolTimeout,
+                            default: .Database.poolTimeout
+                        ))
+                    )
                 )
-            )
-        default:
-            return .inMemory
+            case let token:
+                throw ConfigError.unknownDatabaseDriver(token)
+            }
         }
     }
 
@@ -275,16 +280,45 @@ private extension ConfigReader {
 
     // MARK: Properties
 
-    /// The TLS posture for the PostgreSQL connection, mapped from the `database.tls` key: `off` and `require` map to their postures, and any
-    /// other value falls back to `prefer`.
+    /// The TLS posture for the PostgreSQL connection, mapped from the `database.tls` key.
+    ///
+    /// Any token but `off`, `prefer`, and `require` throws a ``ConfigError``: a mistyped posture (`required`, say) fails the boot rather than
+    /// falling back to `prefer`, which hands the password over in plaintext when the upgrade is stripped.
     var tls: TLS {
-        switch string(
-            forKey: .Database.tls,
-            default: .Database.tls
-        ) {
-        case .Database.tlsOff: .off
-        case .Database.tlsRequire: .require
-        default: .prefer
+        get throws {
+            switch string(
+                forKey: .Database.tls,
+                default: .Database.tls
+            ) {
+            case .Database.tlsOff: .off
+            case .Database.tlsPrefer: .prefer
+            case .Database.tlsRequire: .require
+            case let token: throw ConfigError.unknownDatabaseTLS(token)
+            }
+        }
+    }
+
+}
+
+// MARK: - ConfigError
+
+/// A configuration value the executable refuses to boot with; ``description`` names the tokens the key accepts.
+package enum ConfigError: Error, Equatable, CustomStringConvertible {
+
+    /// The `database.driver` key holds an unrecognized token.
+    case unknownDatabaseDriver(String)
+
+    /// The `database.tls` key holds an unrecognized token.
+    case unknownDatabaseTLS(String)
+
+    // MARK: Computed
+
+    package var description: String {
+        switch self {
+        case .unknownDatabaseDriver(let token):
+            "Unknown 'database.driver' value '\(token)': use '\(String.Database.driverInMemory)' or '\(String.Database.driverPostgres)'."
+        case .unknownDatabaseTLS(let token):
+            "Unknown 'database.tls' value '\(token)': use '\(String.Database.tlsOff)', '\(String.Database.tlsPrefer)', or '\(String.Database.tlsRequire)'."
         }
     }