Nlog

Links

• Getting started

Console project

Nuget packages

• NLog.Extensions.Logging
• Microsoft.Extensions.DependencyInjection
• Microsoft.Extensions.Configuration.Json

Config file

Be sure to have the config file copied to the output folder while building.

appsettings.json

{ "NLog": { "throwConfigExceptions": true, "targets": { "async": true, "console": { "type": "ColoredConsole", "layout": "${level:uppercase=true} - ${logger} - ${message:withexception=true}" } }, "rules": [ { "logger": "*", "minLevel": "Info", "writeTo": "console" } ] } }

Program

Program.cs

var logger = LogManager.GetCurrentClassLogger(); try { var config = new ConfigurationBuilder() .SetBasePath(Directory.GetCurrentDirectory()) .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true) .Build(); // to log in this class only LogManager.Configuration = new NLogLoggingConfiguration(config.GetSection("NLog")); using var servicesProvider = new ServiceCollection() .AddTransient<MyApp>() .AddLogging(loggingBuilder => { // configure Logging with NLog loggingBuilder.ClearProviders(); loggingBuilder.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace); loggingBuilder.AddNLog(config); }).BuildServiceProvider(); var myApp = servicesProvider.GetRequiredService<MyApp>(); myApp.Run(); } catch (Exception ex) { // NLog: catch any exception and log it. logger.Error(ex, "Stopped program because of exception"); throw; } finally { // Ensure to flush and stop internal timers/threads before application-exit (Avoid segmentation fault on Linux) LogManager.Shutdown(); }

Configuration file

Layout

// default layout "layout": "${longdate}|${level:uppercase=true}|${logger}|${message:withexception=true}"

Target

ColoredConsole

appsettings.json

"async": true, // use the asynchronous NLog Console Target "console": { "type": "ColoredConsole", "layout": "${level:uppercase=true} - ${logger} - ${message:withexception=true}", "useDefaultRowHighlightingRules": false, "rowHighlightingRules": [ { "condition": "level == LogLevel.Fatal", "foregroundColor": "Blue", "backgroundColor": "White" } ] }

• NLog Console vs AddConsole

File

appsettings.json

"file": { "type": "File", "fileName": "${basedir}/logs/nlog.log", // Global Mutex Locks "keepFileOpen": true, "concurrentWrites": true, // Size-based file archival "archiveFileName": "${basedir}/archives/nlog.{#####}.log", "archiveAboveSize": 10240, "maxArchiveFiles": 4, "archiveNumbering": "Rolling" }

• FileTarget Archive Examples

Rules

"rules": [ { "logger": "*", "minLevel": "Info", "writeTo": "console, file" }, { "logger": "*", "levels": "Debug", "writeTo": "file" } ]

Filters

Filters apply the default action except for the matching conditions.

"rules": [ { "logger": "*", "minLevel": "Info", "writeTo": "console, file", "filterDefaultAction": "Log", "filters": [ { "type": "when", "condition": "contains('${message}','Common')", "action": "Ignore" } ] } ]

Levels

Level	Description
FATAL	Fatal error messages. After a fatal error, the application usually terminates
ERROR	Error messages
WARN	Warnings which don't appear to the user of the application
INFO	Informational messages
DEBUG	Less detailed and/or less frequent debugging messages
TRACE	Very detailed log messages, potentially of a high frequency and volume