Configuration error of serilog

 FailureSink

https://github.com/serilog/serilog-sinks-elasticsearch/blob/dev/src/Serilog.Sinks.Elasticsearch/Sinks/ElasticSearch/ElasticsearchSinkOptions.cs#L236

  /// <summary>
        /// Sink to use when Elasticsearch is unable to accept the events. This is optional and depends on the EmitEventFailure setting.
        /// </summary>
        public ILogEventSink FailureSink { get; set; }

原来默认的配置

System.InvalidCastException: Invalid cast from 'System.String' to 'Serilog.Core.ILogEventSink'.
at System.Convert.DefaultToType(IConvertible value, Type targetType, IFormatProvider provider)
at System.String.System.IConvertible.ToType(Type type, IFormatProvider provider)
at System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider)
at System.Convert.ChangeType(Object value, Type conversionType)
at Serilog.Settings.KeyValuePairs.SettingValueConversions.ConvertToType(String value, Type toType)
at Serilog.Settings.KeyValuePairs.KeyValuePairSettings.ConvertOrLookupByName(String valueOrSwitchName, Type type, IReadOnlyDictionary`2 declaredSwitches)
at Serilog.Settings.KeyValuePairs.KeyValuePairSettings.<>c__DisplayClass26_0.<ApplyDirectives>b__1(<>f__AnonymousType3`2 <>h__TransparentIdentifier0)
at System.Linq.Enumerable.<>c__DisplayClass7_0`3.<CombineSelectors>b__0(TSource x)
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at Serilog.Settings.KeyValuePairs.KeyValuePairSettings.ApplyDirectives(List`1 directives, IList`1 configurationMethods, Object loggerConfigMethod, IReadOnlyDictionary`2 declaredSwitches)
at Serilog.Settings.KeyValuePairs.KeyValuePairSettings.Configure(LoggerConfiguration loggerConfiguration)
at Serilog.Configuration.LoggerSettingsConfiguration.Settings(ILoggerSettings settings)
at Serilog.Configuration.LoggerSettingsConfiguration.KeyValuePairs(IEnumerable`1 settings)
at Serilog.Settings.AppSettings.AppSettingsSettings.Configure(LoggerConfiguration loggerConfiguration)
at Serilog.Configuration.LoggerSettingsConfiguration.Settings(ILoggerSettings settings)
at Serilog.AppSettingsLoggerConfigurationExtensions.AppSettings(LoggerSettingsConfiguration settingConfiguration, String settingPrefix, String filePath)
at SerilogTest.Program.Main(String[] args) in C:Usersclusource eposSerilogTestSerilogTestProgram.cs:line 29

修改后的配置

<add key="serilog:write-to:Elasticsearch.failureSink" value="SerilogTest.Program, SerilogTest" />

System.ArgumentException: Object of type 'SerilogTest.Program' cannot be converted to type 'Serilog.Core.ILogEventSink'.
at System.RuntimeType.TryChangeType(Object value, Binder binder, CultureInfo culture, Boolean needsSpecialCast)
at System.RuntimeType.CheckValue(Object value, Binder binder, CultureInfo culture, BindingFlags invokeAttr)
at System.Reflection.MethodBase.CheckArguments(Object[] parameters, Binder binder, BindingFlags invokeAttr, CultureInfo culture, Signature sig)
at System.Reflection.RuntimeMethodInfo.InvokeArgumentsCheck(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at Serilog.Settings.KeyValuePairs.KeyValuePairSettings.ApplyDirectives(List`1 directives, IList`1 configurationMethods, Object loggerConfigMethod, IReadOnlyDictionary`2 declaredSwitches)
at Serilog.Settings.KeyValuePairs.KeyValuePairSettings.Configure(LoggerConfiguration loggerConfiguration)
at Serilog.Configuration.LoggerSettingsConfiguration.Settings(ILoggerSettings settings)
at Serilog.Configuration.LoggerSettingsConfiguration.KeyValuePairs(IEnumerable`1 settings)
at Serilog.Settings.AppSettings.AppSettingsSettings.Configure(LoggerConfiguration loggerConfiguration)
at Serilog.Configuration.LoggerSettingsConfiguration.Settings(ILoggerSettings settings)
at Serilog.AppSettingsLoggerConfigurationExtensions.AppSettings(LoggerSettingsConfiguration settingConfiguration, String settingPrefix, String filePath)
at SerilogTest.Program.Main(String[] args) in C:Usersclusource eposSerilogTestSerilogTestProgram.cs:line 32

根据提示，自己实现一个

   class ChuckFailureSink : ILogEventSink
    {
        void ILogEventSink.Emit(LogEvent logEvent)
        {
            throw new NotImplementedException();
        }
    }

然后配置文件，修改为    <add key="serilog:write-to:Elasticsearch.failureSink" value="SerilogTest.ChuckFailureSink, SerilogTest" />

EmitEventFailure

 <add key="serilog:write-to:Elasticsearch.emitEventFailure" value="WriteToFailureSink|WriteToSelfLog" />

https://github.com/serilog/serilog-sinks-elasticsearch/blob/dev/src/Serilog.Sinks.Elasticsearch/Sinks/ElasticSearch/ElasticsearchSinkOptions.cs#L231
https://github.com/serilog/serilog-sinks-elasticsearch/blob/dev/src/Serilog.Sinks.Elasticsearch/Sinks/ElasticSearch/ElasticsearchSinkOptions.cs#L358

  /// <summary>
        /// Specifies how failing emits should be handled.
        /// </summary>
        public EmitEventFailureHandling EmitEventFailure { get; set; }

 /// <summary>
    /// Sepecifies options for handling failures when emitting the events to Elasticsearch. Can be a combination of options.
    /// </summary>
    [Flags]
    public enum EmitEventFailureHandling
    {
        /// <summary>
        /// Send the error to the SelfLog
        /// </summary>
        WriteToSelfLog = 1,

        /// <summary>
        /// Write the events to another sink. Make sure to configure this one.
        /// </summary>
        WriteToFailureSink = 2,

        /// <summary>
        /// Throw the exception to the caller.
        /// </summary>
        ThrowException = 4,

        /// <summary>
        /// The failure callback function will be called when the event cannot be submitted to Elasticsearch.
        /// </summary>
        RaiseCallback = 8
    }