tab3r.netcore.banner 0.0.1

netcore.banner

A Spring Boot–style startup banner for ASP.NET Core (Generic Host applications), built for .NET 8+ with zero third-party dependencies.

Easy to setup: Add one line to Program.cs and get a customizable, placeholder-aware, ANSI-colored banner printed automatically when your service starts, just like Spring Boot does out of the box.

Install

dotnet add package tab3r.netcore.banner

Quick start

using NetCore.Banner;

var builder = WebApplication.CreateBuilder(args);

// Do your MAGIC!!!!
builder.Host.UseBanner();

var app = builder.Build();
app.Run();

That's it. On startup you'll see either your own banner.txt (if present at the content root) or the built-in default banner.

Custom banner.txt

Drop a banner.txt file at your project's content root (copy it to the output directory) and use placeholders.

For example, this is the default banner.txt built-in:

   _   _      _    ____
  | \ | | ___| |_ / ___|___  _ __ ___
  |  \| |/ _ \ __| |   / _ \| '__/ _ \
  | |\  |  __/ |_| |__| (_) | | |  __/
  |_| \_|\___|\__|\____\___/|_|  \___|
${AnsiColor.GREEN} :: ${application.name:-Application} ::${Ansi.NORMAL} ${application.formatted-version:-}
 :: powered by ${dotnet.version} :: ${environment.name:-Production}

Make sure the file is copied on build:

<ItemGroup>
  <None Update="banner.txt">
    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
  </None>
</ItemGroup>

Placeholders

The library allow use placeholders for useful information in the app startup.

Default values: use ${key:-fallback} (note the :- separator, not a plain :) so it never collides with IConfiguration's own : hierarchy separator, e.g. ${Custom:Section:Key} still resolves as a single configuration key.

Colors: ${AnsiColor.RED}, ${AnsiBackground.GREEN}, ${AnsiStyle.BOLD}, and ${Ansi.NORMAL} (reset) emit ANSI escape codes. They are automatically disabled when the output is redirected, when NO_COLOR is set, or when TERM=dumb.

Configuration

Bind via the Banner section in appsettings.json:

{
  "Banner": {
    "Mode": "Console",
    "Location": "banner.txt",
    "Charset": "UTF-8",
    "AnsiMode": "Detect"
  }
}

or override programmatically:

builder.Host.UseBanner(options =>
{
    options.Mode = BannerMode.Log;
    options.Location = "custom-banner.txt";
});

Configuration options

Banner modes

• Console — rendered and written to Console.Out immediately, before the host finishes building (matches Spring Boot's early CONSOLE mode).
• Log — rendered once and emitted through ILogger<BannerHostedService> as soon as logging is available.
• Off — no banner is printed.

Sample

See samples/SampleWebApi for a runnable ASP.NET Core Web API demonstrating a custom banner.txt, appsettings.json configuration, and all three banner modes.