Invex Logging Extensions

Useful utilities for Microsoft.Extensions.Logging.

Packages

Package	What it does
Invex.Extensions.Logging.FancyConsole	A colorful, readable console logger built on Spectre.Console, with multiple layouts, per-level styles, scopes, pretty exceptions, and standard-error routing.
Invex.Extensions.Logging.File	A dependency-light file logger with size- and time-based rollover, retention limits, routing by scoped group and log level, and buffered or synchronous writing.

Both packages are standard logging providers: they plug into any ASP.NET Core, Generic Host, or manually created ILoggerFactory, bind options from the Logging configuration section, pick up configuration changes at runtime, and leave level filtering to the standard logging rules. They target net10.0, net9.0, net8.0, and netstandard2.0, and can be used independently or together.

Quick start

Install one or both packages:

dotnet add package Invex.Extensions.Logging.FancyConsole
dotnet add package Invex.Extensions.Logging.File

Register them with your host. A common setup is readable console output while you watch the app, plus rolling files for later inspection:

using Invex.Extensions.Logging.FancyConsole;
using Invex.Extensions.Logging.File;

var builder = WebApplication.CreateBuilder(args);

builder.Logging.ClearProviders();
builder.Logging.AddFancyConsole();
builder.Logging.AddFile();

var app = builder.Build();

They also work with a manually created logger factory:

using Invex.Extensions.Logging.FancyConsole;
using Invex.Extensions.Logging.File;
using Microsoft.Extensions.Logging;

using var loggerFactory = LoggerFactory.Create(logging => logging
    .AddFancyConsole()
    .AddFile());

var logger = loggerFactory.CreateLogger<Program>();
logger.LogInformation("Hello, world!");

See getting started for defaults and level filtering.

Fancy console logger

AddFancyConsole writes styled, human-friendly output to the console. Pick from four layouts:

Layout	Output
Standard (default)	A date and category header, then time, level, and message, with a blank line between entries.
SingleLine	One line per entry: time, level, category, and message.
Minimal	Only the level and message.
Detailed	Every available field (category, event, thread, scopes, and message), labeled on separate lines.

Standard:

2026-06-11 +10:00 MyApp.Services.OrderService
09:41:23.123  INF Order 42 submitted

SingleLine:

09:41:23.123 INF MyApp.Services.OrderService: Order 42 submitted

Exceptions can be rendered in Full, Spectre.Console Pretty, one-line Summary, or Hidden form, and entries at or above a chosen level can be routed to standard error. Configure in code:

using Invex.Extensions.Logging.FancyConsole;
using Invex.Extensions.Logging.FancyConsole.Configuration;
using Microsoft.Extensions.Logging;

builder.Logging.AddFancyConsole(options =>
{
    options.Layout = FancyConsoleLayout.SingleLine;
    options.IncludeScopes = true;
    options.UseShortCategoryName = true;
    options.LevelStyles[LogLevel.Error] = "bold red";
    options.ExceptionFormat = FancyConsoleExceptionFormat.Pretty;
    options.LogToStandardErrorThreshold = LogLevel.Error;
});

Or under Logging:FancyConsole (provider alias FancyConsole). Values configured by the delegate are applied after values bound from configuration:

{
  "Logging": {
    "FancyConsole": {
      "Layout": "SingleLine",
      "IncludeScopes": true,
      "LevelStyles": {
        "Error": "bold red"
      },
      "ExceptionFormat": "Pretty",
      "LogToStandardErrorThreshold": "Error"
    }
  }
}

Option	Default	Description
Layout	Standard	Standard, SingleLine, Minimal, or Detailed.
TimestampFormat	null	.NET date/time format string; null or empty uses the layout default.
UseUtcTimestamp	false	Show timestamps in UTC instead of local time.
IncludeScopes	false	Append active scopes after the category (Standard and SingleLine; Detailed always shows them).
UseShortCategoryName	false	Shorten categories to the text after their last ..
UseColors	true	Apply styles when the console supports them; NO_COLOR is honored.
LevelStyles	empty	Per-level Spectre.Console styles, such as "bold red" or "black on yellow".
ExceptionFormat	Full	Full, Pretty, Summary, or Hidden.
ExceptionTextStyle	"red1"	Style for Full and Summary exception text.
LogToStandardErrorThreshold	None	Entries at or above this level go to standard error; None writes everything to standard output.

Each entry is written as a single unit, so concurrent entries do not interleave, and rendering failures are never thrown into the application. See the fancy console guide for every layout, style, and exception option.

File logger

AddFile writes plain, parseable log lines to rolling files:

[2026-06-11 09:41:23.123 +10:00 INF MyApp.Services.OrderService] Order 42 submitted

By default it writes to a Logs directory relative to the current working directory. The active file is named after AppDomain.CurrentDomain.FriendlyName, rolls over daily or at 100 MiB (whichever happens first), and retains up to 10 GiB of rolled-over files.

Important

Buffered writing is the default. Dispose the host or ILoggerFactory during graceful shutdown so queued entries are flushed, even when disposal immediately follows the last log call; no delay is needed. Entries still in memory can be lost if the process crashes or is killed.

Configure in code:

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

builder.Logging.AddFile(options =>
{
    options.LogDirectory = "Logs";
    options.LogName = "my-app";
    options.FileSizeLimitBytes = 50L * 1024 * 1024;
    options.RolloverInterval = FileRolloverInterval.Hour;
    options.MaxTotalSizeBytes = 1L * 1024 * 1024 * 1024;
    options.PerGroupLogName["Orders"] = "orders";
    options.PerLevelLogName[LogLevel.Error] = "errors";
});

Or under Logging:File (provider alias File). Values configured by the delegate are applied after values bound from configuration:

{
  "Logging": {
    "File": {
      "LogDirectory": "Logs",
      "LogName": "my-app",
      "FileSizeLimitBytes": 104857600,
      "RolloverInterval": "Day",
      "MaxTotalSizeBytes": 10737418240,
      "PerGroupLogName": {
        "Orders": "orders"
      },
      "PerLevelLogName": {
        "Error": "errors",
        "Critical": "errors"
      }
    }
  }
}

Option	Default	Description
LogDirectory	"Logs"	Absolute directory, or a directory relative to the current working directory. Created when needed.
LogName	null	Active base name without .log; null uses the application domain friendly name.
PerGroupLogName	empty	Suffixes for selected scoped groups, appended to the base name before any level suffix. A mapped null or empty string adds nothing.
PerLevelLogName	empty	Suffixes for selected levels, appended after the base name and any group suffix. A mapped null or empty string adds nothing.
FileSizeLimitBytes	100 MiB	Rolls over before a write that would make the active file reach this size.
RolloverInterval	Day	Elapsed interval from file creation: Infinite, Year (365 days), Month (30 days), Day, Hour, or Minute.
MaxTotalSizeBytes	10 GiB	Maximum total size of rolled-over files for each base name. The oldest rolled-over file is removed when the limit is reached.

Important

PerLevelLogName values now append to LogName as suffixes instead of replacing it. Update existing full-name mappings to suffixes; for example, use "errors" with LogName = "my-app" to write my-app_errors.log. See migration guidance.

Routing by group

Use BeginGroupScope to set a group for log calls within a scope:

using Invex.Extensions.Logging.File;

using (logger.BeginGroupScope("Orders"))
{
    logger.LogInformation("Order submitted"); // my-app_orders.log
    logger.LogError("Payment failed");       // my-app_orders_errors.log
}

File names start with LogName, followed by the mapped group suffix and then the mapped level suffix, each separated by an underscore. Missing mappings and null or empty mapped suffixes add no separator or text. Nested groups override outer groups until disposed, and scopes flow across await and logger categories. Dictionary and formatted scopes such as logger.BeginScope("{Group}", "Orders") also work. Scope values affect routing without appearing in the file's log lines. See group routing for the complete rules.

Rollover, retention, and write modes

When rollover occurs, the active {name}.log is renamed to {name}_{yyMMdd-HHmmss}.log; collisions receive _1, _2, and later suffixes. Time rollover uses elapsed durations, not calendar boundaries, and checks occur only when an entry is written. Retention is evaluated independently for each base name and never deletes the active file. Case-only path aliases follow the destination filesystem's behavior for buffered routing, archive naming, and retention. See file rollover and retention.

Buffered mode queues entries for a dedicated background thread that writes batches of up to 10 entries. Use direct mode when an entry must be written before the log call returns:

builder.Logging.AddFile(buffered: false);

Both modes retry failed writes up to five times, report failures to console/debug output, and drop entries that still cannot be written. See buffered versus direct writing and the log format guide.

Filtering

Neither provider filters levels itself. Use the standard log filtering rules, scoped to a provider alias when needed:

{
  "Logging": {
    "LogLevel": {
      "Default": "Information"
    },
    "FancyConsole": {
      "LogLevel": {
        "Microsoft": "Warning"
      }
    },
    "File": {
      "LogLevel": {
        "Default": "Warning",
        "MyApp.Services": "Information"
      }
    }
  }
}

Documentation

• Getting started
• Fancy console logger: guide
• File logger: configuration, rollover and retention, buffered versus direct writing, and log output format
• API reference

License

Licensed under the terms of LICENSE.txt.