serilog Getting Started

Getting Started

using System;
using Serilog;

namespace SerilogExample
{
    class Program
    {
        static void Main()
        {
            Log.Logger = new LoggerConfiguration()
                .MinimumLevel.Debug()
                .WriteTo.Console()
                .WriteTo.File("logs\myapp.txt", rollingInterval: RollingInterval.Day)
                .CreateLogger();

            Log.Information("Hello, world!");

            int a = 10, b = 0;
            try
            {
                Log.Debug("Dividing {A} by {B}", a, b);
                Console.WriteLine(a / b);
            }
            catch (Exception ex)
            {
                Log.Error(ex, "Something went wrong");
            }

            Log.CloseAndFlush();
            Console.ReadKey();
        }
    }
}

Serilog.Settings.AppSettings 

An XML <appSettings> reader for Serilog

To read configuration from <appSettings> use the ReadFrom.AppSettings() extension method on your LoggerConfiguration:

Log.Logger = new LoggerConfiguration()
  .ReadFrom.AppSettings()
  ... // Other configuration here, then
  .CreateLogger()

You can mix and match XML and code-based configuration, but each sink must be configured either using XML or in code - sinks added in code can't be modified via app settings.

Configuration syntax

To configure the logger, an <appSettings> element should be included in the program's App.config or Web.config file.

https://github.com/serilog/serilog/wiki/AppSettings 

Serilog supports a simple <appSettings>-based configuration syntax in App.config and Web.config files to set the minimum level, enrich events with additional properties, and control log output.

Serilog is primarily configured using code, with settings support intended as a supplementary feature. It is not comprehensive but most logger configuration tasks can be achieved using it.

https://github.com/serilog/serilog-sinks-elasticsearch#quick-start

elasticsearch的配置在单独的项目里面提到

 <appSettings>
    <add key="serilog:using" value="Serilog.Sinks.Elasticsearch"/>
    <add key="serilog:write-to:Elasticsearch.nodeUris" value="http://localhost:9200;http://remotehost:9200"/>
    <add key="serilog:write-to:Elasticsearch.indexFormat" value="custom-index-{0:yyyy.MM}"/>
    <add key="serilog:write-to:Elasticsearch.templateName" value="myCustomTemplate"/>
    <add key="serilog:write-to:Elasticsearch.typeName" value="myCustomLogEventType"/>
    <add key="serilog:write-to:Elasticsearch.pipelineName" value="myCustomPipelineName"/>
    <add key="serilog:write-to:Elasticsearch.batchPostingLimit" value="50"/>
    <add key="serilog:write-to:Elasticsearch.period" value="2"/>
    <add key="serilog:write-to:Elasticsearch.inlineFields" value="true"/>
    <add key="serilog:write-to:Elasticsearch.restrictedToMinimumLevel" value="Warning"/>
    <add key="serilog:write-to:Elasticsearch.bufferBaseFilename" value="C:TempSerilogElasticBuffer"/>
    <add key="serilog:write-to:Elasticsearch.bufferFileSizeLimitBytes" value="5242880"/>
    <add key="serilog:write-to:Elasticsearch.bufferLogShippingInterval" value="5000"/>
    <add key="serilog:write-to:Elasticsearch.bufferRetainedInvalidPayloadsLimitBytes" value="5000"/>
    <add key="serilog:write-to:Elasticsearch.bufferFileCountLimit " value="31"/>
    <add key="serilog:write-to:Elasticsearch.connectionGlobalHeaders" value="Authorization=Bearer SOME-TOKEN;OtherHeader=OTHER-HEADER-VALUE" />
    <add key="serilog:write-to:Elasticsearch.connectionTimeout" value="5" />
    <add key="serilog:write-to:Elasticsearch.emitEventFailure" value="WriteToSelfLog" />
    <add key="serilog:write-to:Elasticsearch.queueSizeLimit" value="100000" />
    <add key="serilog:write-to:Elasticsearch.autoRegisterTemplate" value="true" />
    <add key="serilog:write-to:Elasticsearch.autoRegisterTemplateVersion" value="ESv2" />
    <add key="serilog:write-to:Elasticsearch.overwriteTemplate" value="false" />
    <add key="serilog:write-to:Elasticsearch.registerTemplateFailure" value="IndexAnyway" />
    <add key="serilog:write-to:Elasticsearch.deadLetterIndexName" value="deadletter-{0:yyyy.MM}" />
    <add key="serilog:write-to:Elasticsearch.numberOfShards" value="20" />
    <add key="serilog:write-to:Elasticsearch.numberOfReplicas" value="10" />
    <add key="serilog:write-to:Elasticsearch.formatProvider" value="My.Namespace.MyFormatProvider, My.Assembly.Name" />
    <add key="serilog:write-to:Elasticsearch.connection" value="My.Namespace.MyConnection, My.Assembly.Name" />
    <add key="serilog:write-to:Elasticsearch.serializer" value="My.Namespace.MySerializer, My.Assembly.Name" />
    <add key="serilog:write-to:Elasticsearch.connectionPool" value="My.Namespace.MyConnectionPool, My.Assembly.Name" />
    <add key="serilog:write-to:Elasticsearch.customFormatter" value="My.Namespace.MyCustomFormatter, My.Assembly.Name" />
    <add key="serilog:write-to:Elasticsearch.customDurableFormatter" value="My.Namespace.MyCustomDurableFormatter, My.Assembly.Name" />
    <add key="serilog:write-to:Elasticsearch.failureSink" value="My.Namespace.MyFailureSink, My.Assembly.Name" />
  </appSettings>

Watch the config file at runtime

Try to figure out the feature about watch the App.config at runtime like log4net and NLog
https://stackoverflow.com/questions/25477415/how-can-i-reconfigure-serilog-without-restarting-the-application
https://stackoverflow.com/questions/50715913/serilog-equivalent-to-log4net-config-watch
The above two links have no useful info about reload all settings in App.config.

Here is another link https://stackoverflow.com/questions/53449596/reload-serilog-json-configuration-on-changes-in-net-core-2-1/60474967#60474967
The current Serilog implementation (2.9.0) is such that it is unable to fully reload settings. To work around this issue without introducing additional dependencies, avoid creating static loggers and follow the example provided here: https://github.com/akovac35/Logging/blob/v1.0.4/src/com.github.akovac35.Logging.Serilog/SerilogHelper.cs

Will you consider to implement this feature?

Change logger/sink configuration at runtime?

Thanks for the weigh-in @damianh. I agree there are some rough edges around this scenario, especially existing contextual loggers, as you point out. I think the way existing loggers continue to point to the sinks they were created with falls out from the immutable/stateless design, which isn't ideal here but brings a lot of other benefits. Do you think your workaround is something that could be made general? It seems like the best approach available at this point.... :-)

I think the new WriteTo.Logger() method added in the latest Serilog gets rid of your casting issue:

Log.Logger = new LoggerConfiguration()
      .WriteTo.Logger(Log.Logger)
      .WriteTo.Console().CreateLogger();