Using ELMAH in ASP.NET Core

March 20, 2016 by Anuraj

ASP.NET ELMAH ELM ASP.NET Core Logging

ELMAH (Error Logging Modules and Handlers) is an application-wide error logging facility that is completely pluggable. It can be dynamically added to a running ASP.NET web application, or even all ASP.NET web applications on a machine, without any need for re-compilation or re-deployment. ELMAH does not work with ASP.NET 5 because ELMAH (given its name) is based on ASP.NET 4.x’s Modules and Handlers (the ‘MAH’ of ‘ELMAH’). There is a prototype in ASP.NET 5 called ‘ELM’ (Error Logging Middleware) that has some features similar to ELMAH. This post is about using ELM in ASP.NET 5.

This post is about configuring ELMAH in ASP.NET Core.

First you need to update project.json file and add reference of ELM.

{
    "dependencies": {
        "Microsoft.AspNet.Server.Kestrel": "1.0.0-rc1-final",
        "Microsoft.AspNet.IISPlatformHandler": "1.0.0-rc1-final",
        "Microsoft.AspNet.Diagnostics": "1.0.0-rc1-final",
        "Microsoft.AspNet.Mvc": "6.0.0-rc1-final",
        "Microsoft.AspNet.Diagnostics.Elm": "1.0.0-rc1-final"
    },
    "commands": {
        "web": "Microsoft.AspNet.Server.Kestrel --server.urls http://*:5004"
    },
    "frameworks": {
         "dnx451": { },
         "dnxcore50": { }
    }
}

Next you need to configure the Startup file ConfigureServices and Configure methods to support ELM.

public void ConfigureServices(IServiceCollection services)
{
    services.AddElm();
    services.ConfigureElm(options => {
        options.Path = new PathString("/elm");
        options.Filter = (name, level) => level >= LogLevel.Verbose;
    });
    
    services.AddMvc();
}
public void Configure(IApplicationBuilder app, ILoggerFactory loggerFactory)
{
    app.Map("/HelloMVC6", map => 
    {
        app.UseElmPage();
        app.UseElmCapture();
        app.UseIISPlatformHandler();
        app.UseDeveloperExceptionPage();
        app.UseMvcWithDefaultRoute();
    });
}

Now if you browse http://localhost:5004/elm, you can see the logging information. Due to line break characters in style, the CSS is not working properly.

ASP.NET Core ELM Log

Happy Coding

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