log4net accessing context properties from custom appender

Question

I am using log4net with a custom appender that logs to Azure Storage Tables, and am having issues accessing log4net.GlobalContext properties from within my Appender. I am logging from inside an Azure Function.

The appending is pretty straight forward and simple and works fine, but I would like to add a couple custom properties - one of which is an InvocationId and only accessible from the Azure Functions, so i would like to know the best way to achieve this.

Any idea what I'm missing?

Appender

protected override void Append(LoggingEvent loggingEvent)
{
  _tableCtx.Log(new LogEntry
                {
                  Timestamp = loggingEvent.TimeStamp,
                  Message = loggingEvent.RenderedMessage,
                  Level = loggingEvent.Level.Name,
                  // properties is always empty
                  InvocationId = loggingEvent.Properties["InvocationId"],
                  PartitionKey = loggingEvent.LoggerName,
                 });
}

Azure Function

public static async Task<HttpResponseMessage> MyFunction([HttpTrigger(AuthorizationLevel.Function, "post")]HttpRequestMessage req, ILogger log, ExecutionContext context)
{

  log4net.GlobalContext.Properties["InvocationId"] = context.InvocationId;
  using (var config = Assembly.GetExecutingAssembly().GetManifestResourceStream("MyFunc.logging.config"))
  {
      log4net.Config.XmlConfigurator.Configure(config);
  }

   var log = LogManager.GetLogger(context.FunctionName);
}

Answer 1

Try

loggingEvent.GetProperties()["InvocationId"]

or

loggingEvent.LookupProperty("InvocationId")

See here for more details

Answer 2

You have to set the Property after you initialize log4net:

  using (var config = Assembly.GetExecutingAssembly().GetManifestResourceStream("MyFunc.logging.config"))
  {
      log4net.Config.XmlConfigurator.Configure(config);
  }

  var log = LogManager.GetLogger(context.FunctionName);

  log4net.GlobalContext.Properties["InvocationId"] = context.InvocationId;

You also only have to initialize log4net when it is not yet initialized. Doing it on every call is not very efficient.

Answer 3

我最终做到了这一点，这比我想象的要简单。

log4net.LogicalThreadContext.Properties["InvocationId"].ToString()