Sitecore SEQ Logging

0 - SerilogAppender.cs

using log4net.spi;
using System;
using log4net.helpers;
using Serilog;
using Serilog.Core;
using Serilog.Events;
using ILogger = Serilog.ILogger;

namespace log4net.Appender
{
    public class SerilogAppender : BufferingAppenderSkeleton
    {
        public string MinimumLevel { get; set; }

        public string ApiKey { get; set; }

        public string SeqHost { get; set; }

        [Obsolete("Use the BufferingAppenderSkeleton Fix methods")]
        public bool LocationInfo => false;

        protected override void SendBuffer(LoggingEvent[] events)
        {
            if (string.IsNullOrEmpty(SeqHost))
            {
                return;
            }

            using (
                var log = new LoggerConfiguration()
                    .MinimumLevel.ControlledBy(new LoggingLevelSwitch(GetLogEventLevel(MinimumLevel, LogEventLevel.Information)))
                    .Enrich.WithProperty("ApplicationName", GetSite())
                    .Enrich.WithProperty("SpokeName", GetRoleName().ToLower())
                    .Enrich.FromLogContext()
                    .Enrich.WithMachineName()
                    .Enrich.WithEnvironmentUserName()
                    .Enrich.WithProcessId()
                    .Enrich.WithProcessName()
                    .Enrich.WithProperty("ThreadId", SystemInfo.CurrentThreadId)
                    .Enrich.WithMemoryUsage()
                    .WriteTo.Seq(SeqHost, apiKey: ApiKey)
                    .CreateLogger()
                )
            {
                foreach (var thisEvent in events)
                {
                    LogEvent(log, thisEvent);
                }
            }
        }

        private static string GetSite()
        {
            return !string.IsNullOrWhiteSpace(Sitecore.Context.Site?.Name) ? Sitecore.Context.Site.Name : null;
        }

        private static string GetRoleName()
        {
            var roleName = Sitecore.Configuration.Settings.GetSetting("CloudRoleNameFallback");

            return !string.IsNullOrWhiteSpace(roleName) ? roleName : "RoleName";
        }

        protected override bool RequiresLayout => true;

        private void LogEvent(ILogger log, LoggingEvent loggingEvent)
        {
            try
            {
                var message = RenderLoggingEvent(loggingEvent);
                var level = GetLogEventLevel(loggingEvent.Level.ToString());
                log.Write(level, message);
            }
            catch (Exception ex)
            {
                ErrorHandler.Error("Error occurred while logging the event.", ex);
            }
        }

        private static LogEventLevel GetLogEventLevel(string level, LogEventLevel defaultValue = LogEventLevel.Debug)
        {
            var logEventLevel = defaultValue;
            switch (level.ToLowerInvariant())
            {
                case "debug":
                    logEventLevel = LogEventLevel.Debug;
                    break;
                case "info":
                    logEventLevel = LogEventLevel.Information;
                    break;
                case "warn":
                    logEventLevel = LogEventLevel.Warning;
                    break;
                case "error":
                    logEventLevel = LogEventLevel.Error;
                    break;
                case "fatal":
                    logEventLevel = LogEventLevel.Fatal;
                    break;
            }

            return logEventLevel;
        }
    }
}

1 - reflection usage.cs

// use reflection, because m_thrownException is private field in log4net.spi.LoggingEvent
FieldInfo ExceptionField = typeof(LoggingEvent).GetField("m_thrownException",
            BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
// ...
Exception exception = null;
if (level >= LogEventLevel.Error)
{
    exception = ExceptionField.GetValue(loggingEvent) as Exception;
}
log.Write(level, exception, message);

1 - SerilogAppender.cs

using log4net.spi;
using System;
using System.Reflection;
using Serilog;
using Serilog.Core;
using Serilog.Events;
using ILogger = Serilog.ILogger;
using log4net.helpers;
using Serilog.Exceptions;
using SitecoreSerilog.Extensions;

// ReSharper disable once CheckNamespace
namespace log4net.Appender
{
    public class SerilogAppender : BufferingAppenderSkeleton
    {
        public string MinimumLevel { get; set; }
        
        public string ApiKey { get; set; }
        
        public string SeqHost { get; set; }
        
        [Obsolete("Use the BufferingAppenderSkeleton Fix methods")]
        public bool LocationInfo => false;
        
        private Logger _seqLogger;
        
        private static readonly FieldInfo ExceptionField = typeof(LoggingEvent).GetField("m_thrownException",
            BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
        
        protected override void SendBuffer(LoggingEvent[] events)
        {
            if (_seqLogger == null)
            {
                return;
            }
            
            foreach (var thisEvent in events)
            {
                LogEvent(_seqLogger, thisEvent);
            }
        }
        
        protected override bool RequiresLayout => true;
        
        private void LogEvent(ILogger log, LoggingEvent loggingEvent)
        {
            try
            {
                var message = RenderLoggingEvent(loggingEvent);
                var level = GetLogEventLevel(loggingEvent.Level.ToString());
                Exception exception = null;
                if (level >= LogEventLevel.Error)
                {
                    exception = ExceptionField.GetValue(loggingEvent) as Exception;
                }
                
                log.Write(level, exception, message);
            }
            catch (Exception ex)
            {
                ErrorHandler.Error("Error occurred while logging the event.", ex);
            }
        }
        
        private static LogEventLevel GetLogEventLevel(string level, LogEventLevel defaultValue = LogEventLevel.Debug)
        {
            var logEventLevel = defaultValue;
            switch (level.ToLowerInvariant())
            {
                case "debug":
                    logEventLevel = LogEventLevel.Debug;
                    break;
                case "info":
                    logEventLevel = LogEventLevel.Information;
                    break;
                case "warn":
                    logEventLevel = LogEventLevel.Warning;
                    break;
                case "error":
                    logEventLevel = LogEventLevel.Error;
                    break;
                case "fatal":
                    logEventLevel = LogEventLevel.Fatal;
                    break;
            }
            
            return logEventLevel;
        }
        
        public override void ActivateOptions()
        {
            base.ActivateOptions();
            if (string.IsNullOrEmpty(SeqHost))
            {
                return;
            }
            _seqLogger = new LoggerConfiguration()
                .MinimumLevel
                .ControlledBy(new LoggingLevelSwitch(GetLogEventLevel(MinimumLevel, LogEventLevel.Information)))
                .Enrich.WithFuncEnricher("ApplicationName", GetSite)
                .Enrich.WithFuncEnricher("SpokeName", () => GetRoleName().ToLower())
                .Enrich.FromLogContext()
                .Enrich.WithUtcTimestamp()
                .Enrich.WithMachineName()
                .Enrich.WithEnvironmentUserName()
                .Enrich.WithProcessId()
                .Enrich.WithProcessName()
                .Enrich.WithFuncEnricher("ThreadId", () => SystemInfo.CurrentThreadId)
                .Enrich.WithMemoryUsage()
                .Enrich.WithExceptionDetails()
                .WriteTo.Seq(SeqHost, apiKey: ApiKey, batchPostingLimit: BufferSize)
                .CreateLogger();
            _seqLogger.Information("SEQ Initialized");
        }
        
        public override void OnClose()
        {
            base.OnClose();
            _seqLogger.Information("SEQ Disposing");
            _seqLogger?.Dispose();
        }
        
        private static string GetSite()
        {
            return !string.IsNullOrWhiteSpace(Sitecore.Context.Site?.Name) ? Sitecore.Context.Site.Name : "N/A";
        }
        
        private static string GetRoleName()
        {
            var roleName = Sitecore.Configuration.Settings.GetSetting("CloudRoleNameFallback");
            
            return !string.IsNullOrWhiteSpace(roleName) ? roleName : "RoleName";
        }
    }
}