Roslyn analyzers for elmah.io and ASP.NET Core

The Roslyn analyzers for elmah.io and ASP.NET Core has reached end of life. The analyzers are no longer updated and won't work for top-level statements or when configuring Elmah.Io.AspNetCore in the Program.cs file. To validate the installation we recommend running the diagnose command as explained here: Diagnose potential problems with an elmah.io installation.

To help to install elmah.io in ASP.NET Core (by using the Elmah.Io.AspNetCore NuGet package) we have developed a range of Roslyn analyzers. Analyzers run inside Visual Studio and make it possible to validate your Startup.cs file during development.

Installation and usage

The analyzers can be installed in two ways. As a NuGet package or a Visual Studio extension. To install it from NuGet:

Install-Package Elmah.Io.AspNetCore.Analyzers

dotnet add package Elmah.Io.AspNetCore.Analyzers

<PackageReference Include="Elmah.Io.AspNetCore.Analyzers" Version="0.*" />

paket add Elmah.Io.AspNetCore.Analyzers

The package is installed as a private asset, which means that it is not distributed as part of your build. You can keep the package installed after you have used it to inspect any warnings generated or uninstall it.

To install it as a Visual Studio extension, navigate to Extensions | Manage extensions | Online and search for Elmah.Io.AspNetCore.Analyzers. Then click the Download button and restart Visual Studio. As an alternative, you can download the extension directly from the Visual Studio Marketplace.

Once installed, analyzers will help you add or move elmah.io-related setup code:

Roslyn analyzers

All issues are listed as warnings in the Error list as well. The following is an explanation of possible warnings.

EIO1000 ConfigureServices must call AddElmahIo

AddElmahIo needs to be added as part of the ConfigureServices method:

public void ConfigureServices(IServiceCollection services)
{
    services.AddElmahIo(/*...*/); //👈
}

EIO1001 Configure must call UseElmahIo

UseElmahIo needs to be added as part of the Configure method:

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    app.UseElmahIo(); //👈
}

EIO1002 UseElmahIo must be called before/after Use*

UseElmahIo needs to be called after any calls to UseDeveloperExceptionPage, UseExceptionHandler, UseAuthorization, and UseAuthentication but before any calls to UseEndpoints and UseMvc:

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }
    else
    {
        app.UseExceptionHandler(/*...*/);
    }

    app.UseAuthentication();
    app.UseAuthorization();

    app.UseElmahIo(); //👈

    app.UseEndpoints();
    app.UseMvc(/*...*/);
}


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