Configuration

The file logger is configured via the FileLoggerConfiguration options class. Options can be supplied from configuration (the Logging:File section), from code, or both — values set in code override bound values.

Options reference

Option	Type	Default	Description
LogDirectory	string	"Logs"	Directory for log files. Absolute, or relative to the current working directory. Created automatically.
LogName	string?	null	Base file name (no extension). null uses the application's name (AppDomain.CurrentDomain.FriendlyName).
PerLevelLogName	Dictionary<LogLevel, string?>	empty	Per-level overrides of the file name, routing specific levels to separate files.
FileSizeLimitBytes	long	104857600 (100 MiB)	Maximum size of a single log file before it is rolled over.
RolloverInterval	FileRolloverInterval	Day	Time-based rollover interval: Infinite, Year, Month, Day, Hour, or Minute.
MaxTotalSizeBytes	long	10737418240 (10 GiB)	Maximum combined size of rolled-over files before the oldest is deleted.

Configuring via appsettings.json

The provider registers under the alias File, so it binds to the Logging:File section:

{
  "Logging": {
    "File": {
      "LogDirectory": "C:/logs/my-app",
      "LogName": "my-app",
      "FileSizeLimitBytes": 52428800,
      "RolloverInterval": "Hour",
      "MaxTotalSizeBytes": 1073741824,
      "PerLevelLogName": {
        "Error": "my-app-errors",
        "Critical": "my-app-errors"
      }
    }
  }
}

Note

RolloverInterval accepts the enum names: Infinite, Year, Month, Day, Hour, Minute.

Configuring in code

using Invex.Extensions.Logging.File;
using Invex.Extensions.Logging.File.Configuration;

builder.Logging.AddFile(options =>
{
    options.LogDirectory = "Logs";
    options.LogName = "my-app";
    options.FileSizeLimitBytes = 50L * 1024 * 1024; // 50 MiB
    options.RolloverInterval = FileRolloverInterval.Hour;
    options.MaxTotalSizeBytes = 1L * 1024 * 1024 * 1024; // 1 GiB

    options.PerLevelLogName[LogLevel.Error] = "my-app-errors";
    options.PerLevelLogName[LogLevel.Critical] = "my-app-errors";
});

Routing levels to separate files

PerLevelLogName maps a LogLevel to an alternative base file name. Levels present in the dictionary write to {name}.log instead of the default file; levels not present continue to use LogName.

builder.Logging.AddFile(options =>
{
    options.LogName = "app";

    // Errors and critical entries go to their own file
    options.PerLevelLogName[LogLevel.Error] = "app-errors";
    options.PerLevelLogName[LogLevel.Critical] = "app-errors";

    // Trace entries go to a separate diagnostic file
    options.PerLevelLogName[LogLevel.Trace] = "app-trace";
});

Produces:

Logs/
    app.log          <- Debug, Information, Warning
    app-errors.log   <- Error, Critical
    app-trace.log    <- Trace

Each file rolls over and is purged independently, using the same FileSizeLimitBytes, RolloverInterval, and MaxTotalSizeBytes settings.

Tip

A null value in PerLevelLogName is valid and falls back to the application's name for that level — useful if LogName is customized but you want certain levels in the default-named file.

Runtime configuration changes

The provider monitors its options with IOptionsMonitor<T>. Changes to the Logging:File section in appsettings.json (or any reloadable configuration source) are picked up automatically and applied to subsequent log writes — no restart required.

Default constants

All defaults are exposed as public constants on FileLoggerConfiguration for use in your own code:

• FileLoggerConfiguration.DefaultLogDirectory
• FileLoggerConfiguration.DefaultLogName
• FileLoggerConfiguration.DefaultFileSizeLimitBytes
• FileLoggerConfiguration.DefaultRollingInterval
• FileLoggerConfiguration.DefaultMaxTotalSizeBytes