How To Archive Log Files Using NLog With ASP.NET Core

Introduction

In this article, you will learn how to archive log files using NLog with ASP.NET Core .

Most of the time, we will store logs in files, and we should archive them so that we can manage them easier. Let's take a look at how to use NLog to archive log files.

Step 1

Create a new ASP.NET Core Web API Application and install NLog.Web.AspNetCore via nuget.

Install-Package NLog.Web.AspNetCore

Step 2 

Create a nlog.config file, and enable copy to bin folder.

We just archive the log files via this configuration file.

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      autoReload="true"
      throwConfigExceptions="true">

  <!-- the targets to write to -->
  <targets>

    <target xsi:type="File"
        name="archive"
        archiveEvery="Day"
        archiveFileName = "nlogdemo-{########}.log"
        archiveNumbering = "Date"
        archiveDateFormat = "yyyyMMdd"
        maxArchiveFiles = "4"
        fileName="nlogdemo.log"
        layout="${longdate}|${level:uppercase=true}|${logger}|${message}" />

    </targets>

  <!-- rules to map from logger name to target -->
  <rules>
    <!--All logs, including from Microsoft-->
    <logger name="*" minlevel="Warn" writeTo="archive" />
  </rules>
</nlog>

Just pay attention to the opions that contains archive.

The above configuration means that we hava a main log file named nlogdemo.log which stores today's log.

It will archive logs daily and the file name of the archive log file will be formatted like nlogdemo-20180505.log.

And the max number of archived log files is 4 which means it will keep only the newest 4 files.

Step 3

Update program.cs so that we can enable NLog. 

namespace NLogDemo
{
    using Microsoft.AspNetCore;
    using Microsoft.AspNetCore.Hosting;
    using NLog.Web;

    public class Program
    {
        public static void Main(string[] args)
        {
            BuildWebHost(args).Run();
        }

        public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .UseNLog()
                .Build();
    }
}

Step 4

Write some logs in controller. 

private readonly ILogger _logger;

public ValuesController(ILoggerFactory loggerFactory)
{
    _logger = loggerFactory.CreateLogger<ValuesController>();
}

// GET api/values
[HttpGet]
public IEnumerable<string> Get()
{
    _logger.LogDebug("debug");
    _logger.LogError("error");
    _logger.LogTrace("trace");
    _logger.LogInformation("info");
    _logger.LogWarning("warn");
    _logger.LogCritical("critical");

    return new string[] { "value1", "value2" };
}

Now, change the date of computer to see the results.

 

 

 

Source Code

• Github

Summary

This article introduced the basic configuration to acrchive log files using NLog.

 

Hope this can help you.