Using outputTemplate argument in Serilog with Azure Application Insights

Question

I'm currently implementing Azure Application Insights logging with Serilog which is working fine except for when I use an output template in my Serilog configuration. It seems like the template is ignored when passing the Serilog data to Application insights.

My serilog config in appsetting.json:

"Serilog": {
    "Using": [ "Serilog.Sinks.ApplicationInsights" ],
    "MinimumLevel": "Debug",
    "WriteTo": [
      { "Name": "Console" },
      {
        "Name": "RollingFile",
        "Args": {
          "pathFormat": "logs\\log-{Date}.txt",
          "outputTemplate": "{Timestamp:yyyy-MM-dd HH:mm:ss.fff zzz} [{Level}] {Message}{NewLine}{Exception}"
        }
      },
      {
        "Name": "ApplicationInsights",
        "Args": {
          "restrictedToMinimumLevel": "Information",
          "telemetryConverter": "Serilog.Sinks.ApplicationInsights.Sinks.ApplicationInsights.TelemetryConverters.TraceTelemetryConverter, Serilog.Sinks.ApplicationInsights",
          "outputTemplate": "Test Template - {Message}"
        }
      }
    ],
    "Enrich": [ "FromLogContext", "WithMachineName", "WithThreadId" ],
    "Properties": {
      "Application": "app"
    }
  },

The logging statement:

logger.Error("Test Serilog Error For AI - " + DateTime.Now);

The output within application insights:

Is this the correct approach to customising an error message for Application insights?

Answer 1

After checking the source code serilog-sinks-applicationinsights, you will find it did not read the outputTemplate from appsetting.json.

For a workaround, you may implement custom TemplateTraceTelemetryConverter.

1. TemplateTraceTelemetryConverter

   public class TemplateTraceTelemetryConverter : TraceTelemetryConverter
   {
       public override IEnumerable<ITelemetry> Convert(LogEvent logEvent, IFormatProvider formatProvider)
       {
           var templateParser = new MessageTemplateParser();
           var template = templateParser.Parse($"Test Template - {logEvent.MessageTemplate.Text}");
           LogEvent newLogEvent = new LogEvent(logEvent.Timestamp
               , logEvent.Level
               , logEvent.Exception
               , template
               , logEvent.Properties.Select(p => new LogEventProperty(p.Key, p.Value)));
           return base.Convert(newLogEvent, formatProvider);
       }
   }
   

2. Use TemplateTraceTelemetryConverter

   "Serilog": {
       "Using": [
       "Serilog.Sinks.ApplicationInsights",
       ],
       "MinimumLevel": "Debug",
       "WriteTo": [
       {
           "Name": "Console",
           "Args": {
           "outputTemplate": "Test Template - {Message}"
           }
       },
       {
           "Name": "RollingFile",
           "Args": {
           "pathFormat": "logs\\log-{Date}.txt",
           "outputTemplate": "{Timestamp:yyyy-MM-dd HH:mm:ss.fff zzz} [{Level}] {Message}{NewLine}{Exception}"
           }
       },
       {
           "Name": "ApplicationInsights",
           "Args": {
           "restrictedToMinimumLevel": "Error",          
           "telemetryConverter": "YourProjectNamespace.TemplateTraceTelemetryConverter, YourProjectNamespace"
           //"outputTemplate": "Test Template - {Message}"
           }
       }
       ],
       "Enrich": [ "FromLogContext", "WithMachineName", "WithThreadId" ],
       "Properties": {
       "Application": "app"
       }
   }