It is possible to run a suave.io app on Azure Web Apps because of an IIS8 feature called HttpPlatformHandler. I tried to run a self-hosted OWIN application the same way, but got an exception on startup:
Unhandled Exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Net.HttpListenerException: Access is denied
at System.Net.HttpListener.SetupV2Config()
at System.Net.HttpListener.Start()
at Microsoft.Owin.Host.HttpListener.OwinHttpListener.Start(HttpListener listener, Func`2 appFunc, IList`1 addresses, IDictionary`2 capabilities, Func`2 loggerFactory)
at Microsoft.Owin.Host.HttpListener.OwinServerFactory.Create(Func`2 app, IDictionary`2 properties)
--- End of inner exception stack trace ---
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at Microsoft.Owin.Hosting.ServerFactory.ServerFactoryAdapter.Create(IAppBuilder builder)
at Microsoft.Owin.Hosting.Engine.HostingEngine.StartServer(StartContext context)
at Microsoft.Owin.Hosting.Engine.HostingEngine.Start(StartContext context)
at Microsoft.Owin.Hosting.Starter.DirectHostingStarter.Start(StartOptions options)
at Microsoft.Owin.Hosting.Starter.HostingStarter.Start(StartOptions options)
at Microsoft.Owin.Hosting.WebApp.StartImplementation(IServiceProvider services, StartOptions options)
at Microsoft.Owin.Hosting.WebApp.Start(StartOptions options)
at Microsoft.Owin.Hosting.WebApp.Start[TStartup](StartOptions options)
at Microsoft.Owin.Hosting.WebApp.Start[TStartup](String url)
at WebAppSample.Program.Main(String[] args) in c:\Users\egger\Workspace\WebAppSample\WebAppSample\Program.cs:line 14
It seems that I am not allowed to open a port. My web.config looks like this:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<handlers>
<remove name="httpplatformhandler" />
<add name="httpplatformhandler" path="*" verb="*" modules="httpPlatformHandler" resourceType="Unspecified" />
</handlers>
<httpPlatform
stdoutLogEnabled="true"
stdoutLogFile="site.log"
startupTimeLimit="20"
processPath="%HOME%\site\wwwroot\WebAppSample.exe"
arguments="%HTTP_PLATFORM_PORT%">
</httpPlatform>
</system.webServer>
</configuration>
I use HTTP_PLATFORM_PORT to listen on the right port. My web app starts the server as follows:
class Program
{
static void Main(string[] args)
{
var port = int.Parse(args[0]);
var url = string.Format("http://127.0.0.1:{0}", port);
Console.WriteLine("Starting web app at {0}", url);
using (WebApp.Start<Startup>(url))
{
Console.ReadLine();
}
}
}
public class Startup
{
public void Configuration(IAppBuilder app)
{
app.UseErrorPage();
app.UseWelcomePage("/");
}
}
The URL seems to be OK because I get output like this: Starting web app at http://127.0.0.1:32880.
The web.config and all the binaries are in the root directory and I published the app using a local git repo.
Why can't I open the port using OWIN? What's different from the suave.io sample?
EDIT: I just saw there is a request to support this exact scenario: https://feedback.azure.com/forums/169385-web-apps-formerly-websites/suggestions/4606121-support-owin-self-hosting-in-azure-websites
