Using Serilog

Setup

Install the package Akka.Logger.Serilog via nuget to utilize Serilog, this will also install the required Serilog package dependencies.

PM> Install-Package Akka.Logger.Serilog

Example

The following example uses Serilogs Colored Console sink available via nuget, there are wide range of other sinks available depending on your needs, for example a rolling log file sink. See serilogs documentation for details on these.

PM> Install-Package Serilog.Sinks.ColoredConsole

Next, you'll need to configure the global Log.Logger and also specify to use the logger in the config when creating the system, for example like this:

var logger = new LoggerConfiguration()
    .WriteTo.ColoredConsole()
    .MinimumLevel.Information()
    .CreateLogger();

Serilog.Log.Logger = logger;

var system = ActorSystem.Create("my-test-system", "akka { loglevel=INFO,  loggers=[\"Akka.Logger.Serilog.SerilogLogger, Akka.Logger.Serilog\"]}");

Logging

To log inside an actor, using the normal string.Format() syntax, get the logger and log:

var log = Context.GetLogger();
...
log.Info("The value is {0}", counter);

Or alternatively

var log = Context.GetLogger();
...
log.Info("The value is {Counter}", counter);

Extensions

The package Akka.Logger.Serilog also includes the extension method ForContext() for ILoggingAdapter (the object returned by Context.GetLogger()). This is analogous to Serilog's ForContext() but instead of returning a Serilog ILogger it returns an Akka.NET ILoggingAdapter. This instance acts as contextual logger that will attach a property to all events logged through it.

However, in order to use it, the parent ILoggingAdapter must be constructed through another included generic extension method for GetLogger(). For example,

using Akka.Logger.Serilog;
...
private readonly ILoggingAdapter _logger = Context.GetLogger<SerilogLoggingAdapter>();
...
private void ProcessMessage(string correlationId)
{
    var contextLogger = _logger.ForContext("CorrelationId", correlationId);
    contextLogger.Info("Processing message");
}

If the configured output template is, for example, "[{CorrelationId}] {Message}{NewLine}", and the parameter correlationId is "1234" then the resulting log would contain the line [1234] Processing message.

// configure sink with an output template
var logger = new LoggerConfiguration()
    .WriteTo.ColoredConsole(outputTemplate: "[{CorrelationId}] {Message}{NewLine}")
    .MinimumLevel.Information()
    .CreateLogger();

HOCON configuration

In order to be able to change log level without the need to recompile, we need to employ some sort of application configuration. To use Serilog via HOCON configuration, add the following to the App.config of the project.

<configSections>    
    <section name="akka" type="Akka.Configuration.Hocon.AkkaConfigurationSection, Akka" />
</configSections>

...

<akka>
    <hocon>
      <![CDATA[
      akka { 
        loglevel=INFO,
        loggers=["Akka.Logger.Serilog.SerilogLogger, Akka.Logger.Serilog"]
      }
    ]]>
    </hocon>
  </akka>

The code can then be updated as follows removing the inline HOCON from the actor system creation code. Note in the following example, if a minimum level is not specfied, Information level events and higher will be processed. Please read the documentation for Serilog configuration for more details on this. It is also possible to move serilog configuration to the application configuration, for example if using a rolling log file sink, again, browsing the serilog documentation is the best place for details on that feature.

var logger = new LoggerConfiguration()
                .WriteTo.ColoredConsole()
                .MinimumLevel.Information()
                .CreateLogger();

Serilog.Log.Logger = logger;

var system = ActorSystem.Create("my-test-system");