Logging

Logging and Logging Libraries for .NET

Updated: 03 September 2023

Logging can be done in a bunch of different ways, but the best one I’ve found this far is Serilog, and the setup is as follows:

Install Serilog

You will need to add the following dependencies to your application from NuGet

  1. Serilog
  2. Serilog.Sinks.Console
  3. Serilog.Sinks.File
  4. Serilog.Settings.Configuration

Basic Logger

Setting up a basic logger that will log to a file or console can be done as follows, using rolling log files and logger instances that can be shared between processes. There are a lot of other config options but these are the main ones

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using Serilog;
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using Serilog.Events;
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...
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var logger = new LoggerConfiguration()
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        .WriteTo.Console()
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        .WriteTo.File("logs/log.txt", shared: true)
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        .WriteTo.File("debug/debug.txt", shared: true, rollingInterval: RollingInterval.Hour, restrictedToMinimumLevel: LogEventLevel.Debug)
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        .WriteTo.File("fatal/fatal.txt", shared: true, rollingInterval: RollingInterval.Day, restrictedToMinimumLevel: LogEventLevel.Fatal)
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        .CreateLogger();
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logger.Information("Hello World!");

Using Configuration

Additionally you can set the loggers up using the appsettings.json file as well, for which the Serilog parts will be as follows

appsettings.json

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{
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...
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  "Serilog": {
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    "WriteTo": [
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      {
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        "Name": "File",
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        "Args": {
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          "path": "logs/info/info-.txt",
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          "rollingInterval": "Day",
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          "shared": true
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        }
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      },
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      {
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        "Name": "File",
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        "Args": {
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          "path": "logs/errors/errors-.txt",
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          "rollingInterval": "Day",
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          "shared": true,
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          "restrictedToMinimumLevel": "Warning"
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        }
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      }
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    ]
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  },
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 ...
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 }

This can then be loaded into a logger instance with:

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var config = new ConfigurationBuilder()
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    .AddJsonFile("appsettings.json")
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    .Build();
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var logger = new LoggerConfiguration()
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                .WriteTo.Console()
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                .ReadFrom
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                .Configuration(config)
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                .CreateLogger();

Logging Service

Lastly, you can also make use of a logger service in Web Application using the Startup.cs/ConfigureServices function with the following:

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services.AddScoped<Serilog.ILogger>(serviceProvider =>
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    new LoggerConfiguration()
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        .WriteTo.Console()
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        .ReadFrom
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        .Configuration(serviceProvider.GetRequiredService<IConfiguration>())
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        .CreateLogger()
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);

And then use this using Dependency Injecton on a Controller’s Constructor like:

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public MyStuffController(Serilog.ILogger logger)
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{
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  _logger = logger;
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}

And then simply use the logger where required

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public string TestLog()
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{
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  _logger.Information("Some Log Stuff");
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}