Make it possible to change the master database name

src/dbup-postgresql/PostgresqlConnectionOptions.cs

@@ -14,9 +14,14 @@ public class PostgresqlConnectionOptions
         public X509Certificate2 ClientCertificate { get; set; }
 
         /// <summary>
-        //  Custom handler to verify the remote SSL certificate.
-        //  Ignored if Npgsql.NpgsqlConnectionStringBuilder.TrustServerCertificate is set.
+        ///  Custom handler to verify the remote SSL certificate.
+        ///  Ignored if Npgsql.NpgsqlConnectionStringBuilder.TrustServerCertificate is set.
         /// </summary>
         public RemoteCertificateValidationCallback UserCertificateValidationCallback { get; set; }
+
+        /// <summary>
+        /// The database to connect to initially. Default is 'postgres'.
+        /// </summary>
+        public string MasterDatabaseName { get; set; } = "postgres";
     }
 }

src/dbup-postgresql/PostgresqlExtensions.cs

@@ -159,7 +159,12 @@ private static void PostgresqlDatabase(this SupportedDatabasesForEnsureDatabase
         PostgresqlDatabase(supported, connectionString, logger, options);
     }
 
-    private static void PostgresqlDatabase(this SupportedDatabasesForEnsureDatabase supported, string connectionString, IUpgradeLog logger, PostgresqlConnectionOptions connectionOptions)
+    private static void PostgresqlDatabase(
+        this SupportedDatabasesForEnsureDatabase supported, 
+        string connectionString, 
+        IUpgradeLog logger, 
+        PostgresqlConnectionOptions connectionOptions
+    )
     {
         if (supported == null) throw new ArgumentNullException("supported");
 
@@ -179,7 +184,7 @@ private static void PostgresqlDatabase(this SupportedDatabasesForEnsureDatabase
             throw new InvalidOperationException("The connection string does not specify a database name.");
         }
 
-        masterConnectionStringBuilder.Database = "postgres";
+        masterConnectionStringBuilder.Database = connectionOptions.MasterDatabaseName;
 
         var logMasterConnectionStringBuilder = new NpgsqlConnectionStringBuilder(masterConnectionStringBuilder.ConnectionString);
         if (!string.IsNullOrEmpty(logMasterConnectionStringBuilder.Password))