README.md

Serilog.Extensions.WhenRepeated

A wrapper for other Serilog sinks. Matches when message has already been logged. Useful if having an aggressive logger, and wants to throttle the output.

Getting started

Install from NuGet:

Install-Package Serilog.Extensions.WhenRepeated 

Minimal example

// At this example duplicated messages are written as as dot
...
private static readonly MessageTemplate RepeatedMessageTemplate = new MessageTemplate(new MessageTemplateParser().Parse(".").Tokens);

new LoggerConfiguration()
  .Enrich.WithRepeatedMessagesCount("repeatCount")
  .WriteTo
  .WhenRepeated(
    configureWrappedSink: x => x.Async(y => y.File("/path/to/log.txt")),
    options: new WhenRepeatedOptions(
      onRepeat: (current, previous) =>
      {
        return new LogEvent(
          timestamp: current.Timestamp,
          level: current.Level,
          exception: null,
          messageTemplate: RepeatedMessageTemplate,
          properties: Array.Empty<LogEventProperty>());
      })).CreateLogger();
...

Options

The WhenRepeatedOptions type constructor exposes the following members.

Name	Description
onRepeat	Action to be taken when filter matches.
compare	Statement of that how to compare current log with previous log event.
timeout	Duration after which message if duplicated will be logged.
firstStrategy	Strategy that determines how to handle first (not duplicated) log event.

Enrichment

Enrich Serilog events with repeated messages count property.

...
new LoggerConfiguration()
  .Enrich.WithRepeatedMessagesCount("repeatCount") // Set name under which property will be available
  .WriteTo
  .WhenRepeated(
    configureWrappedSink: x => x.Async(y => y.File("/path/to/log.txt")),
    options: new WhenRepeatedOptions() // Default options, needed to enable counting. By default increment repeated messages count when same message occurs in 10 seconds time interval.
  ).CreateLogger();
...
logger.Information(messageTemplate: "{repeatCount}");