Added ability to pass root level Serilog logger to Topshelf so both T…

…opshelf code and app code can share the same logger. Topshelf#234

src/Topshelf.Serilog/Logging/SerilogLogWriterFactory.cs

@@ -19,14 +19,9 @@ public class SerilogLogWriterFactory : LogWriterFactory
     {
         readonly Func<string, ILogger> _loggerFactory;
 
-        SerilogLogWriterFactory(LoggerConfiguration loggerConfiguration)
+        SerilogLogWriterFactory(ILogger logger)
         {
-            _loggerFactory = name => loggerConfiguration.CreateLogger().ForContext("SourceContext", name);
-        }
-
-        SerilogLogWriterFactory()
-        {
-            _loggerFactory = name => Log.ForContext("SourceContext", name);
+            _loggerFactory = name => logger.ForContext("SourceContext", name);
         }
 
         public LogWriter Get(string name)
@@ -38,35 +33,24 @@ public void Shutdown()
         {
         }
 
-        public static void Use()
+        public static void Use(ILogger logger)
         {
-            HostLogger.UseLogger(new SerilogHostLoggerConfigurator());
-        }
-
-        public static void Use(LoggerConfiguration loggerConfiguration)
-        {
-            HostLogger.UseLogger(new SerilogHostLoggerConfigurator(loggerConfiguration));
+            HostLogger.UseLogger(new SerilogHostLoggerConfigurator(logger));
         }
 
         [Serializable]
         public class SerilogHostLoggerConfigurator : HostLoggerConfigurator
         {
-            readonly LoggerConfiguration _factory;
-
-            public SerilogHostLoggerConfigurator(LoggerConfiguration factory)
-            {
-                _factory = factory;
-            }
+            readonly ILogger _logger;
 
-            public SerilogHostLoggerConfigurator()
+            public SerilogHostLoggerConfigurator(ILogger logger)
             {
+                _logger = logger;
             }
 
             public LogWriterFactory CreateLogWriterFactory()
             {
-                return _factory == null 
-                    ? new SerilogLogWriterFactory() 
-                    : new SerilogLogWriterFactory(_factory);
+                return new SerilogLogWriterFactory(_logger);
             }
         }
     }

src/Topshelf.Serilog/SerilogConfigurationExtensions.cs

@@ -23,15 +23,23 @@ public static class SerilogConfigurationExtensions
         /// </summary>
         public static void UseSerilog(this HostConfigurator configurator)
         {
-            SerilogLogWriterFactory.Use();
+            SerilogLogWriterFactory.Use(Log.Logger);
         }
 
         /// <summary>
         /// Configures Topshelf to use Serilog for logging, using the given <see cref="LoggerConfiguration"/> to create loggers.
         /// </summary>
         public static void UseSerilog(this HostConfigurator configurator, LoggerConfiguration loggerConfiguration)
         {
-            SerilogLogWriterFactory.Use(loggerConfiguration);
+            SerilogLogWriterFactory.Use(loggerConfiguration.CreateLogger());
+        }
+
+        /// <summary>
+        /// Configures Topshelf to use Serilog for logging, using the given root logger <see cref="ILogger"/> to create loggers.
+        /// </summary>
+        public static void UseSerilog(this HostConfigurator configurator, ILogger rootLogger)
+        {
+            SerilogLogWriterFactory.Use(rootLogger);
         }
     }
 }