Create multiple log files using Serilog

[ranjithjains]

I would like to know if we can log to multiple files in Serilog.
For example, i would like to create logs of TYPE1 to one file and TYPE2 to another file.

[ranjithjains]

Hi @nblumhardt any help with this.

[ranjithjains]

@nblumhardt i have created an application with logging functionality using Serilog. I would like to create two log files. One log file for application startup and the other file for other functionality of the application.

[tsimbalar]

Hi @ranjithjains ,

take a look at Serilog.Sinks.Map , the README more or less covers that scenario.

[nblumhardt]

It's also possible just to create two separate Loggers via separate LoggerConfigurations and use them independently. Closing as this is a stale ticket now, but please let us know if you need more details @ranjithjains .

[Maru9961]

any solution yet?

[cocowalla]

@Maru9961 there are 2 solutions, both already mentioned here in this thread.

1. Create a sink for each type:

Log.Logger = new LoggerConfiguration()
	.WriteTo.Logger(x =>
	{
		x.WriteTo.File("event_type_1.txt");
		x.Filter.ByIncludingOnly(e => e.Properties["event_type"] == "type_1");
	})
	.WriteTo.Logger(x =>
	{
		x.WriteTo.File("event_type_1.txt");
		x.Filter.ByIncludingOnly(e => e.Properties["event_type"] == "type_2");
	})
	.CreateLogger();

2. Use Serilog.Sinks.Map, which does the same but with nicer config syntax:

Log.Logger = new LoggerConfiguration()
	.WriteTo.Map("event_type", "type_1", (name, wt) => wt.File("event_type_1.txt"))
	.WriteTo.Map("event_type", "type_2", (name, wt) => wt.File("event_type_2.txt"))
	.CreateLogger();

[frankmehlhop]

@cocowalla Thank you for your code above!
I wonder how can I use the two different types (1 and 2) in code also on the run?
I think of some thing like "__logger.Log<type_2>("...");"?

[cocowalla]

@frankmehlhop I think you are asking how to log as event_type 1 and 2 at runtime? This is done using logging context.

As per the docs, there are multiple ways to do this:

1. Create a logger just for such events:

var eventType1Logger = Log.ForContext("event_type", "type_1");

2. Use an ambient/temporary log context

using (LogContext.PushProperty("event_type", "type_1"))
{
    // Process request; all logged events will carry `event_type`
    Log.Information("This log message will have an event_type property");
}

You can do this for individual logs, or with an extensibility point in whatever framework you are using. For example, if you are using ASP.NET Core, you could use middleware:

public async Task Invoke(HttpContext context)
{
    if (!some_check_to_add_event_type_1)
        return;

    using (LogContext.PushProperty("event_type", "type_1"))
    {
        await this.next.Invoke(context);
    }
}

3. You can use globally attached properties:

Log.Logger = new LoggerConfiguration()
    .Enrich.WithProperty("event_type ", "type_1")
    .Enrich.WithProperty("Environment", ConfigurationManager.AppSettings["Environment"])
    // Other logger configuration

4. You can use an ILogEventEnricher to programmatically enrich logs

For (3), if you want to attach the event_type on a log-by-log basis, you can make it nicer with an extension method:

public static class LogExtensions
{
    public static ILogger AsEventType1(this ILogger log)
        => log.ForContext("event_type", "type_1");
}
...
Log.AsEventType1().Error("Something happened!");

[frankmehlhop]

Thank you!