I have an ASP.NET MVC web role running on Windows Azure and have setup ELMAH properly in the web.config. I also have my global.asax ignore *.axd routes. Locally, I am able to load /elmah.axd, however when I deploy to Azure, I get a 404 on that page. Has anyone gotten ELMAH working on Azure?
Asp.net-mvc – How to configure ELMAH to work with Windows Azure? I get a 404 on Elmah.axd
asp.netasp.net-mvcazureelmah
Related Solutions
The code is taken from http://blogs.microsoft.co.il/blogs/shay/archive/2009/03/06/real-world-error-hadnling-in-asp-net-mvc-rc2.aspx and works in ASP.net MVC 1.0 as well
Here's how I handle http exceptions:
protected void Application_Error(object sender, EventArgs e)
{
Exception exception = Server.GetLastError();
// Log the exception.
ILogger logger = Container.Resolve<ILogger>();
logger.Error(exception);
Response.Clear();
HttpException httpException = exception as HttpException;
RouteData routeData = new RouteData();
routeData.Values.Add("controller", "Error");
if (httpException == null)
{
routeData.Values.Add("action", "Index");
}
else //It's an Http Exception, Let's handle it.
{
switch (httpException.GetHttpCode())
{
case 404:
// Page not found.
routeData.Values.Add("action", "HttpError404");
break;
case 500:
// Server error.
routeData.Values.Add("action", "HttpError500");
break;
// Here you can handle Views to other error codes.
// I choose a General error template
default:
routeData.Values.Add("action", "General");
break;
}
}
// Pass exception details to the target error View.
routeData.Values.Add("error", exception);
// Clear the error on server.
Server.ClearError();
// Avoid IIS7 getting in the middle
Response.TrySkipIisCustomErrors = true;
// Call target Controller and pass the routeData.
IController errorController = new ErrorController();
errorController.Execute(new RequestContext(
new HttpContextWrapper(Context), routeData));
}
You can subclass HandleErrorAttribute
and override its OnException
member (no need to copy) so that it logs the exception with ELMAH and only if the base implementation handles it. The minimal amount of code you need is as follows:
using System.Web.Mvc;
using Elmah;
public class HandleErrorAttribute : System.Web.Mvc.HandleErrorAttribute
{
public override void OnException(ExceptionContext context)
{
base.OnException(context);
if (!context.ExceptionHandled)
return;
var httpContext = context.HttpContext.ApplicationInstance.Context;
var signal = ErrorSignal.FromContext(httpContext);
signal.Raise(context.Exception, httpContext);
}
}
The base implementation is invoked first, giving it a chance to mark the exception as being handled. Only then is the exception signaled. The above code is simple and may cause issues if used in an environment where the HttpContext
may not be available, such as testing. As a result, you will want code that is that is more defensive (at the cost of being slightly longer):
using System.Web;
using System.Web.Mvc;
using Elmah;
public class HandleErrorAttribute : System.Web.Mvc.HandleErrorAttribute
{
public override void OnException(ExceptionContext context)
{
base.OnException(context);
if (!context.ExceptionHandled // if unhandled, will be logged anyhow
|| TryRaiseErrorSignal(context) // prefer signaling, if possible
|| IsFiltered(context)) // filtered?
return;
LogException(context);
}
private static bool TryRaiseErrorSignal(ExceptionContext context)
{
var httpContext = GetHttpContextImpl(context.HttpContext);
if (httpContext == null)
return false;
var signal = ErrorSignal.FromContext(httpContext);
if (signal == null)
return false;
signal.Raise(context.Exception, httpContext);
return true;
}
private static bool IsFiltered(ExceptionContext context)
{
var config = context.HttpContext.GetSection("elmah/errorFilter")
as ErrorFilterConfiguration;
if (config == null)
return false;
var testContext = new ErrorFilterModule.AssertionHelperContext(
context.Exception,
GetHttpContextImpl(context.HttpContext));
return config.Assertion.Test(testContext);
}
private static void LogException(ExceptionContext context)
{
var httpContext = GetHttpContextImpl(context.HttpContext);
var error = new Error(context.Exception, httpContext);
ErrorLog.GetDefault(httpContext).Log(error);
}
private static HttpContext GetHttpContextImpl(HttpContextBase context)
{
return context.ApplicationInstance.Context;
}
}
This second version will try to use error signaling from ELMAH first, which involves the fully configured pipeline like logging, mailing, filtering and what have you. Failing that, it attempts to see whether the error should be filtered. If not, the error is simply logged. This implementation does not handle mail notifications. If the exception can be signaled then a mail will be sent if configured to do so.
You may also have to take care that if multiple HandleErrorAttribute
instances are in effect then duplicate logging does not occur, but the above two examples should get your started.
Best Answer
Azure is based on Windows Server 2008 and IIS7. This means that you need to populate the system.webServer part of the web.config file.
The sample file included with elmah's source code contains the details that you need to put in.
There are 2 elmah lines in the above block of xml that you will need to include, and the section in general should contain most if not all of those elements anyway.
EDIT: No longer required as this is now on by default:
For Elmah to work you will also need to modify the following line in your ServiceDefinition.csdef file: