feat: Enable startup logging to Event Log for all applications on Windows.

src/Agent/NewRelic/Agent/Core/Core.csproj

@@ -43,6 +43,7 @@
     <PackageReference Include="Serilog.Sinks.Async" Version="1.5.0" />
     <PackageReference Include="Serilog.Sinks.Console" Version="4.1.0" />
     <PackageReference Include="Serilog.Sinks.Debug" Version="2.0.0" />
+    <PackageReference Include="Serilog.Sinks.EventLog" Version="3.1.0" />
     <PackageReference Include="Serilog.Sinks.File" Version="5.0.0" />
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />
     <PackageReference Include="ILRepack" Version="2.0.16" />
@@ -60,7 +61,6 @@
     <PackageReference Include="Grpc" Version="2.46.6" />
     <PackageReference Include="Grpc.Core" Version="2.46.6" />
     <PackageReference Include="System.Runtime.InteropServices.RuntimeInformation" Version="4.3.0" />
-    <PackageReference Include="Serilog.Sinks.EventLog" Version="3.1.0" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
@@ -129,13 +129,14 @@
       <ILRepackInclude Include="@(PossibleRefsForILRepack)" Condition="'%(FileName)' == 'Serilog.Sinks.Async'" />
       <ILRepackInclude Include="@(PossibleRefsForILRepack)" Condition="'%(FileName)' == 'Serilog.Sinks.Console'" />
       <ILRepackInclude Include="@(PossibleRefsForILRepack)" Condition="'%(FileName)' == 'Serilog.Sinks.Debug'" />
+      <ILRepackInclude Include="@(PossibleRefsForILRepack)" Condition="'%(FileName)' == 'Serilog.Sinks.EventLog'" />
       <ILRepackInclude Include="@(PossibleRefsForILRepack)" Condition="'%(FileName)' == 'Serilog.Sinks.File'" />
       <ILRepackInclude Include="@(PossibleRefsForILRepack)" Condition="'%(FileName)' == 'ICSharpCode.SharpZipLib'" />
     </ItemGroup>
 
     <PropertyGroup>
       <ILRepackIncludeCount Condition="'$(TargetFramework)' == 'net462'">20</ILRepackIncludeCount>
-      <ILRepackIncludeCount Condition="'$(TargetFramework)' == 'netstandard2.0'">16</ILRepackIncludeCount>
+      <ILRepackIncludeCount Condition="'$(TargetFramework)' == 'netstandard2.0'">17</ILRepackIncludeCount>
     </PropertyGroup>
 
     <Error Text="ILRepack of $(AssemblyName) ($(TargetFramework)) failed. A dependency is missing. Expected $(ILRepackIncludeCount) dependencies but found @(ILRepackInclude-&gt;Count())." Condition="@(ILRepackInclude-&gt;Count()) != $(ILRepackIncludeCount)" />

src/Agent/NewRelic/Agent/Core/Logging/LoggerBootstrapper.cs

@@ -11,8 +11,9 @@
 using Logger = NewRelic.Agent.Core.Logging.Logger;
 using NewRelic.Agent.Core.Logging;
 using Serilog.Templates;
-#if NETFRAMEWORK
 using Serilog.Events;
+#if NETSTANDARD2_0
+using System.Runtime.InteropServices;
 #endif
 
 namespace NewRelic.Agent.Core
@@ -107,33 +108,46 @@ private static LoggerConfiguration ConfigureInMemoryLogSink(this LoggerConfigura
         }
 
         /// <summary>
-        /// Add the Event Log sink if running on .NET Framework
+        /// Configure an Event Log sink if running on Windows. Logs messages at Warning level and above. Intended for
+        /// use during bootstrapping and as a fallback if the file logging sink can't be created.
+        ///
+        /// The Agent will create the event log source if it doesn't exist *and* if the app is running with
+        /// administrator privileges. Otherwise, it will silently do nothing.
+        ///
+        /// It is possible to manually create the event log source in an elevated Powershell window:
+        ///    New-EventLog -LogName "Application" -Source "New Relic .NET Agent"
+        /// 
         /// </summary>
         /// <param name="loggerConfiguration"></param>
         private static LoggerConfiguration ConfigureEventLogSink(this LoggerConfiguration loggerConfiguration)
         {
-#if NETFRAMEWORK
-            const string eventLogName = "Application";
-            const string eventLogSourceName = "New Relic .NET Agent";
-            try
+#if NETSTANDARD2_0
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows)) // event log is a Windows-only construct
             {
-                loggerConfiguration
-                        .WriteTo.Logger(configuration =>
-                        {
-                            configuration
-                            .ExcludeAuditLog()
-                            .WriteTo.EventLog(
-                                source: eventLogSourceName,
-                                logName: eventLogName,
-                                restrictedToMinimumLevel: LogEventLevel.Warning,
-                                outputTemplate: "{Level}: {Message}{NewLine}{Exception}",
-                                manageEventSource: true // Serilog will create the event source if it doesn't exist *and* if the app is running with admin privileges
-                            );
-                        });
-            }
-            catch
-            {
-                // ignored -- there's nothing we can do at this point, as EventLog is our "fallback" logger and if it fails, we're out of luck
+#endif
+                const string eventLogName = "Application";
+                const string eventLogSourceName = "New Relic .NET Agent";
+                try
+                {
+                    loggerConfiguration
+                            .WriteTo.Logger(configuration =>
+                            {
+                                configuration
+                                .ExcludeAuditLog()
+                                .WriteTo.EventLog(
+                                    source: eventLogSourceName,
+                                    logName: eventLogName,
+                                    restrictedToMinimumLevel: LogEventLevel.Warning,
+                                    outputTemplate: "{Level}: {Message}{NewLine}{Exception}",
+                                    manageEventSource: true
+                                );
+                            });
+                }
+                catch
+                {
+                    // ignored -- there's nothing we can do at this point, as EventLog is our "fallback" logger and if it fails, we're out of luck
+                }
+#if NETSTANDARD2_0
             }
 #endif
             return loggerConfiguration;
@@ -197,11 +211,10 @@ private static LoggerConfiguration ConfigureFileSink(this LoggerConfiguration lo
             catch (Exception ex)
             {
                 Log.Logger.Warning(ex, "Unexpected exception when configuring file sink.");
-#if NETFRAMEWORK
+
                 // Fallback to the event log sink if we cannot setup a file logger.
                 Log.Logger.Warning("Falling back to EventLog sink.");
                 loggerConfiguration.ConfigureEventLogSink();
-#endif
             }
 
             return loggerConfiguration;