Logging

Jiří Urban, Tomáš Juřička, Stanislav Čermák, Karolína Nesrstová, David Długosz, Tomáš Trčka

Introduction to Logging

• Recording events in an application
• Important for debugging, auditing, and performance monitoring
• Types of logging: Text, structured, and event logging

Logging in .NET

• .NET has a built-in logging framework called Microsoft.Extensions.Logging
• Framework provides loggers, providers, filters, and formatters
• Framework is customizable and supports third-party providers such as Serilog and NLog
• Microsoft.Extensions.Logging.ApplicationInsights package can be added to a .NET 7 WebApi app to provide integration with Azure Application Insights for cloud-based logging and analytics

Logging levels

• Trace = 0
• Debug = 1
• Information = 2
• Warning = 3
• Error = 4
• Critical = 5
• None = 6

Logging implementation

Logging to Console

Program.cs

...

builder.Logging.AddConsole();

...

Logging to console

Logging to file

• Need of third-party library like Serilog
• Add following packages to project:
  • Serilog
  • Serilog.AspNetCore
  • Serilog.Sinks.File

Program.cs

Log.Logger = new LoggerConfiguration()
    .MinimumLevel.Debug()
    .WriteTo.File("logs/myapp.txt", rollingInterval: RollingInterval.Minute)
    .CreateLogger();

builder.Host.UseSerilog();

Logging to file

Logging to JSON

Program.cs

Log.Logger = new LoggerConfiguration()
    .MinimumLevel.Debug()
    .WriteTo.File(new JsonFormatter(), "logs/myapp.json",
        rollingInterval: RollingInterval.Minute)
    .CreateLogger();

builder.Host.UseSerilog();

Logging to JSON

Log search and analytics engines

• Elastic
• Splunk
• Graylog
• Fluentd
• Logz.io
• Papertrail

Log search and analytics engines

Elastic with Kibana

AppInsights