RobotsTxtCore 3.0.0

There is a newer prerelease version of this package available.
See the version list below for details.
dotnet add package RobotsTxtCore --version 3.0.0
NuGet\Install-Package RobotsTxtCore -Version 3.0.0
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="RobotsTxtCore" Version="3.0.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add RobotsTxtCore --version 3.0.0
#r "nuget: RobotsTxtCore, 3.0.0"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install RobotsTxtCore as a Cake Addin
#addin nuget:?package=RobotsTxtCore&version=3.0.0

// Install RobotsTxtCore as a Cake Tool
#tool nuget:?package=RobotsTxtCore&version=3.0.0

RobotsTxtCore NuGet Badge

A Robots.txt middleware for ASP.NET Core. Why is this needed you ask? Because if you need to add dynamic values (such as a configured url from your CMS) you'll need some sort of code to handle that, and this makes it easy.

Installation

.Net CLI

> dotnet add package RobotsTxtCore

NuGet

PM> Install-Package RobotsTxtCore

Changes from 1.0 to 2.0

The first version of this package was only a middleware and had to be configured in the Configure method in the Startup class. This felt fine at the time but as more and more things moved to having configuration as a service and then letting the middleware consume the service I felt like this package got outdated.

So I've made a breaking change and made the middleware consume a IRobotsTxtProvider which in turn takes care of configuration. There is a default provider for static uses (i.e. exactly what the old one did) but doing it this way also let me optimize it quite a lot. A quick benchmark shows that running a thousand requests against /robots.txt is now done in 25% of the time while also lowering allocations about the same.

NuGetReferences Mean Error StdDev Gen 0 Gen 1 Allocated
RobotsTxtCore 1.1.0 1,169.2 μs 22.62 μs 27.77 μs 691.4063 1.9531 4,242 KB
RobotsTxtCore 2.0.0-preview1 419.8 μs 3.88 μs 3.24 μs 167.9688 - 1,031 KB
RobotsTxtCore 2.0.0-preview2 431.5 μs 2.90 μs 2.57 μs 150.3906 - 922 KB
RobotsTxtCore 2.0.0-preview3 307.4 μs 2.00 μs 1.87 μs 155.2734 - 953 KB

Sure, it was really fast to start with and there are very few sites where /robots.txt gets a ton of traffic but that doesn't mean it's not worth it 😉.

Introducing the IRobotsTxtProvider also allows for easier dynamic usage, like reading settings from a database or switching depending on which environment the code is executing in.

Usage

To specify multiple rules with the fluent interface makes it really easy.

public void ConfigureServices(IServiceCollection services) {
    services.AddStaticRobotsTxt(builder =>
        builder
            .AddSection(section =>
                section
                    .AddComment("Allow Googlebot")
                    .AddUserAgent("Googlebot")
                    .Allow("/")
                )
            .AddSection(section =>
                section
                    .AddComment("Disallow the rest")
                    .AddUserAgent("*")
                    .AddCrawlDelay(TimeSpan.FromSeconds(10))
                    .Disallow("/")
                )
            .AddSitemap("https://example.com/sitemap.xml")
    );
}

public void Configure(IApplicationBuilder app) {
    app.UseRobotsTxt();
}

Output

# Allow Googlebot
User-agent: Googlebot
Allow: /

# Disallow the rest
User-agent: *
Disallow: /
Crawl-delay: 10

Sitemap: https://example.com/sitemap.xml

Or if you just want to deny everyone.

public void ConfigureServices(IServiceCollection services) {
    services.AddStaticRobotsTxt(builder =>
        builder
            .DenyAll()
    );
}

public void Configure(IApplicationBuilder app) {
    app.UseRobotsTxt();
}

Output

User-agent: *
Disallow: /

Since version 3.0 you can call AddStaticRobotsTxt multiple times and specify different settings for different environments. If there is a matching envrionment it will be used, otherwise it will fall back to any configuration without an environment specified.

public void ConfigureServices(IServiceCollection services) {
    services.AddStaticRobotsTxt(builder =>
        builder
            .ForEnvironment("Production")
            .AddSection(section =>
                section
                    .AddComment("Allow Googlebot")
                    .AddUserAgent("Googlebot")
                    .Allow("/")
                )
    );

    services.AddStaticRobotsTxt(builder =>
        builder
            .DenyAll()
    );
}

public void Configure(IApplicationBuilder app) {
    app.UseRobotsTxt();
}

IRobotsTxtProvider

IRobotsTxtProvider allows for dynamicly configuring the Robots.txt output depending on your case. It could be used to read from config, to check a database setting or perhaps which environment your application is currently running in.

public class CoolRobotsTxtProvider : IRobotsTxtProvider {
    private readonly CoolContext _context;

    public CoolRobotsTxtProvider(CoolContext context) {
        _context = context;
    }

    public async Task<RobotsTxtResult> GetResultAsync(CancellationToken cancellationToken) {
        var settings = await _context.Settings.FirstAsync();

        var builder = new RobotsTxtOptionsBuilder();

        RobotsTxtOptions options;
        if(settings.AllowAllRobots)
            options = builder.AllowAll().Build();
        else
            options = builder.DenyAll().Build();

        var content = options.ToString();
        var buffer = Encoding.UTF8.GetBytes(content).AsMemory();
        return new RobotsTxtResult(buffer, settings.RobotsTxtMaxAge);
    }
}
Product Compatible and additional computed target framework versions.
.NET net6.0 is compatible.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 is compatible.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 is compatible.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
Compatible target framework(s)
Additional computed target framework(s)
Learn more about Target Frameworks and .NET Standard.
  • net6.0

    • No dependencies.
  • net7.0

    • No dependencies.
  • net8.0

    • No dependencies.

NuGet packages (2)

Showing the top 2 NuGet packages that depend on RobotsTxtCore:

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Apprio.Enablement.Web.Api

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Deali-Axy/StarBlog
☀☀功能完整的博客系统。后端基于.Net6+AspNetCore框架,遵循RESTFul接口规范,前端基于Vue+ElementUI开发,搭配全套开发笔记文章,可作为 .Net Core 入门项目学习~
Version Downloads Last updated
3.1.0-preview1 1,344 10/16/2023
3.0.0 34,921 10/1/2023
2.2.0 80,845 12/24/2022
2.1.1 36,928 6/24/2022
2.0.0 57,059 11/18/2021
2.0.0-preview3 356 9/11/2021
2.0.0-preview2 283 9/9/2021
2.0.0-preview1 263 9/9/2021
1.1.0 254,300 8/11/2019
1.0.1 6,439 2/27/2018
1.0.0 1,008 2/24/2018
1.0.0-beta-2 939 1/2/2018
1.0.0-beta-1 897 12/29/2017