UseNLog supporting isolated LogFactory (#782)

Author: snakefoot

src/NLog.Extensions.Hosting/Extensions/ConfigureExtensions.cs

@@ -45,6 +45,32 @@ public static IHostBuilder UseNLog(this IHostBuilder builder, NLogProviderOption
             return builder;
         }
 
+        /// <summary>
+        /// Enable NLog as logging provider for Microsoft Extension Logging
+        /// </summary>
+        /// <param name="builder"></param>
+        /// <param name="options">NLogProviderOptions object to configure NLog behavior</param>
+        /// <param name="factoryBuilder">Initialize NLog LogFactory with NLog LoggingConfiguration.</param>
+        /// <returns>IHostBuilder for chaining</returns>
+        public static IHostBuilder UseNLog(this IHostBuilder builder, NLogProviderOptions options, Func<IServiceProvider, LogFactory> factoryBuilder)
+        {
+            Guard.ThrowIfNull(builder);
+#if NETSTANDARD2_0
+            builder.ConfigureServices((builderContext, services) => AddNLogLoggerProvider(services, builderContext.Configuration, null, options, (serviceProvider, config, hostEnv, opt) =>
+#else
+            builder.ConfigureServices((builderContext, services) => AddNLogLoggerProvider(services, builderContext.Configuration, builderContext.HostingEnvironment, options, (serviceProvider, config, hostEnv, opt) =>
+#endif
+            {
+                config = serviceProvider.SetupNLogConfigSettings(config, LogManager.LogFactory);
+
+                // Delay initialization of targets until we have loaded config-settings
+                var logFactory = factoryBuilder(serviceProvider);
+                var provider = CreateNLogLoggerProvider(serviceProvider, config, hostEnv, opt, logFactory);
+                return provider;
+            }));
+            return builder;
+        }
+
 #if NET8_0_OR_GREATER
         /// <summary>
         /// Enable NLog as logging provider for Microsoft Extension Logging
@@ -66,7 +92,29 @@ public static IHostApplicationBuilder UseNLog(this IHostApplicationBuilder build
         public static IHostApplicationBuilder UseNLog(this IHostApplicationBuilder builder, NLogProviderOptions options)
         {
             Guard.ThrowIfNull(builder);
-            builder.Services.TryAddNLogLoggingProvider((svc, addlogging) => svc.AddLogging(addlogging), builder.Configuration, options, (provider, cfg, opt) => CreateNLogLoggerProvider(provider, cfg, builder.Environment, opt));
+            builder.Services.TryAddNLogLoggingProvider((svc, addlogging) => svc.AddLogging(addlogging), builder.Configuration, options, (serviceProvider, config, opt) => CreateNLogLoggerProvider(serviceProvider, config, builder.Environment, opt));
+            return builder;
+        }
+
+        /// <summary>
+        /// Enable NLog as logging provider for Microsoft Extension Logging
+        /// </summary>
+        /// <param name="builder"></param>
+        /// <param name="options">NLogProviderOptions object to configure NLog behavior</param>
+        /// <param name="factoryBuilder">Initialize NLog LogFactory with NLog LoggingConfiguration.</param>
+        /// <returns>IHostApplicationBuilder for chaining</returns>
+        public static IHostApplicationBuilder UseNLog(this IHostApplicationBuilder builder, NLogProviderOptions options, Func<IServiceProvider, LogFactory> factoryBuilder)
+        {
+            Guard.ThrowIfNull(builder);
+            builder.Services.TryAddNLogLoggingProvider((svc, addlogging) => svc.AddLogging(addlogging), builder.Configuration, options, (serviceProvider, config, opt) =>
+            {
+                config = serviceProvider.SetupNLogConfigSettings(config, LogManager.LogFactory);
+
+                // Delay initialization of targets until we have loaded config-settings
+                var logFactory = factoryBuilder(serviceProvider);
+                var provider = CreateNLogLoggerProvider(serviceProvider, config, builder.Environment, opt, logFactory);
+                return provider;
+            });
             return builder;
         }
 #endif
@@ -78,7 +126,12 @@ private static void AddNLogLoggerProvider(IServiceCollection services, IConfigur
 
         private static NLogLoggerProvider CreateNLogLoggerProvider(IServiceProvider serviceProvider, IConfiguration hostConfiguration, IHostEnvironment hostEnvironment, NLogProviderOptions options)
         {
-            NLogLoggerProvider provider = serviceProvider.CreateNLogLoggerProvider(hostConfiguration, options, null);
+            return serviceProvider.CreateNLogLoggerProvider(hostConfiguration, options, LogManager.LogFactory);
+        }
+
+        private static NLogLoggerProvider CreateNLogLoggerProvider(IServiceProvider serviceProvider, IConfiguration hostConfiguration, IHostEnvironment hostEnvironment, NLogProviderOptions options, LogFactory logFactory)
+        {
+            NLogLoggerProvider provider = serviceProvider.CreateNLogLoggerProvider(hostConfiguration, options, logFactory);
 
             string nlogConfigFile = string.Empty;
             string contentRootPath = hostEnvironment?.ContentRootPath;

test/NLog.Extensions.Hosting.Tests/ExtensionMethodTests.cs

@@ -34,6 +34,24 @@ public void UseNLog_withOptionsParam_WorksWithNLog()
             TestHostingResult(actual, true);
         }
 
+        [Fact]
+        public void UseNLog_ShouldLogToNLog()
+        {
+            var nlogTarget = new Targets.MemoryTarget() { Name = "Output" };
+            var builder = new HostBuilder().UseNLog(null, (serviceProvider) =>
+            {
+                var nLogFactory = new LogFactory().Setup().LoadConfiguration(c => c.ForLogger().WriteTo(nlogTarget)).LogFactory;
+                return nLogFactory;
+            });
+
+            var loggerFactory = builder.Build().Services.GetService<ILoggerFactory>();
+            Assert.NotNull(loggerFactory);
+
+            var logger = loggerFactory.CreateLogger("Hello");
+            logger.LogCritical("World");
+            Assert.Single(nlogTarget.Logs);
+        }
+
         [Fact]
         public void UseNLog_withConfiguration_WorksWithNLog()
         {
@@ -258,6 +276,27 @@ public void IHostApplicationBuilder_UseNLog_LoadConfigurationFromSection()
             //Reset
             LogManager.Configuration = null;
         }
+
+        [Fact]
+        public void IHostApplicationBuilder_UseNLog_ShouldLogToNLog()
+        {
+            var nlogTarget = new Targets.MemoryTarget() { Name = "Output" };
+            var builder = new HostApplicationBuilder();
+            builder.UseNLog(null, (ServiceProvider) =>
+            {
+                var nLogFactory = new LogFactory().Setup().LoadConfiguration(c => c.ForLogger().WriteTo(nlogTarget)).LogFactory;
+                return nLogFactory;
+            });
+
+            var actual = builder.Build();
+
+            var loggerFactory = actual.Services.GetService<ILoggerFactory>();
+            Assert.NotNull(loggerFactory);
+
+            var logger = loggerFactory.CreateLogger("Hello");
+            logger.LogCritical("World");
+            Assert.Single(nlogTarget.Logs);
+        }
 #endif
     }
 }