About

Microsoft.Extensions.Logging.Abstractions provides abstractions of logging. Interfaces defined in this package are implemented by classes in Microsoft.Extensions.Logging and other logging packages.

This package includes a logging source generator that produces highly efficient and optimized code for logging message methods.

Key Features

• Define main logging abstraction interfaces like ILogger, ILoggerFactory, ILoggerProvider, etc.

How to Use

Custom logger provider implementation example

using Microsoft.Extensions.Logging;

public sealed class ColorConsoleLogger : ILogger
{
    private readonly string _name;
    private readonly Func<ColorConsoleLoggerConfiguration> _getCurrentConfig;

    public ColorConsoleLogger(
        string name,
        Func<ColorConsoleLoggerConfiguration> getCurrentConfig) =>
        (_name, _getCurrentConfig) = (name, getCurrentConfig);

    public IDisposable? BeginScope<TState>(TState state) where TState : notnull => default!;

    public bool IsEnabled(LogLevel logLevel) =>
        _getCurrentConfig().LogLevelToColorMap.ContainsKey(logLevel);

    public void Log<TState>(
        LogLevel logLevel,
        EventId eventId,
        TState state,
        Exception? exception,
        Func<TState, Exception?, string> formatter)
    {
        if (!IsEnabled(logLevel))
        {
            return;
        }

        ColorConsoleLoggerConfiguration config = _getCurrentConfig();
        if (config.EventId == 0 || config.EventId == eventId.Id)
        {
            ConsoleColor originalColor = Console.ForegroundColor;

            Console.ForegroundColor = config.LogLevelToColorMap[logLevel];
            Console.WriteLine($"[{eventId.Id,2}: {logLevel,-12}]");

            Console.ForegroundColor = originalColor;
            Console.Write($"     {_name} - ");

            Console.ForegroundColor = config.LogLevelToColorMap[logLevel];
            Console.Write($"{formatter(state, exception)}");

            Console.ForegroundColor = originalColor;
            Console.WriteLine();
        }
    }
}

Create logs

// Worker class that uses logger implementation of teh interface ILogger<T>

public sealed class Worker : BackgroundService
{
    private readonly ILogger<Worker> _logger;

    public Worker(ILogger<Worker> logger) =>
        _logger = logger;

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            _logger.LogInformation("Worker running at: {time}", DateTimeOffset.UtcNow);
            await Task.Delay(1_000, stoppingToken);
        }
    }
}

Use source generator

public static partial class Log
{
    [LoggerMessage(
        EventId = 0,
        Level = LogLevel.Critical,
        Message = "Could not open socket to `{hostName}`")]
    public static partial void CouldNotOpenSocket(this ILogger logger, string hostName);
}

public partial class InstanceLoggingExample
{
    private readonly ILogger _logger;

    public InstanceLoggingExample(ILogger logger)
    {
        _logger = logger;
    }

    [LoggerMessage(
        EventId = 0,
        Level = LogLevel.Critical,
        Message = "Could not open socket to `{hostName}`")]
    public partial void CouldNotOpenSocket(string hostName);
}

Main Types

The main types provided by this library are:

• Microsoft.Extensions.Logging.ILogger
• Microsoft.Extensions.Logging.ILoggerProvider
• Microsoft.Extensions.Logging.ILoggerFactory
• Microsoft.Extensions.Logging.ILogger<TCategoryName>
• Microsoft.Extensions.Logging.LogLevel
• Microsoft.Extensions.Logging.Logger<T>
• Microsoft.Extensions.Logging.LoggerMessage
• Microsoft.Extensions.Logging.Abstractions.NullLogger

Additional Documentation

• Conceptual documentation
• API documentation

Related Packages

Microsoft.Extensions.Logging
Microsoft.Extensions.Logging.Console
Microsoft.Extensions.Logging.Debug
Microsoft.Extensions.Logging.EventSource
Microsoft.Extensions.Logging.EventLog
Microsoft.Extensions.Logging.TraceSource

Feedback & Contributing

Microsoft.Extensions.Logging.Abstractions is released as open source under the MIT license. Bug reports and contributions are welcome at the GitHub repository.