Add note to call UseRouting after UsePathBase

[halter73]

We plan to fix UsePathBase() in .NET 7 so it's unnecessary to call UseRouting() afterwards like we did for UseExceptionHandler(), UseStatusCodePagesWithReExecute() and UseRewriter() in .NET 6. dotnet/aspnetcore#35426

For now, we want to document that explicitly calling UseRouting() is necessary for UsePathBase() to work with WebApplication.

Partially addresses: dotnet/aspnetcore#38448

[guardrex]

Just a couple of nits and bits.

[marcelo-g-simas]

I've hit this issue today and the proposed workaround is not working for me.

This was a .net 3.1 mvc that was migrated to use the new web app builder but I retained the StartUp class.

Here's the code from Program where the builder and StartUp are created:

            var builder = WebApplication.CreateBuilder(new WebApplicationOptions
            {
                ApplicationName = typeof(Program).Assembly.FullName,
                Args = args,
                EnvironmentName = environment,
            });

            builder.Configuration.AddConfiguration(config);
            builder.Host.UseSerilog();
            builder.WebHost.UseUrls("http://*:58471");
            builder.WebHost.ConfigureKestrel(serverOptions =>
            {
                serverOptions.Limits.MinRequestBodyDataRate = new MinDataRate(
                    bytesPerSecond: 80, gracePeriod: TimeSpan.FromSeconds(20));
                serverOptions.Limits.MinResponseDataRate = new MinDataRate(
                    bytesPerSecond: 80, gracePeriod: TimeSpan.FromSeconds(20));
            });
            var startup = new Startup(config);
            startup.ConfigureServices(builder.Services);
            var app = builder.Build();
            startup.Configure(app, environment);

This is the method in StartUp that is called by Program to initialize the app after it is created:

        public void Configure(IApplicationBuilder app, string environment)
        {
            Dapper.DefaultTypeMap.MatchNamesWithUnderscores = true;
            // The request path has to be set if the application is running in a
            // container and being exposed on a path other than /.  In k8s we set
            // SiteConfig__PathBase to /sms in most projects.
            if (!string.IsNullOrEmpty(Cfg.SiteConfig.PathBase))
            {
                Log.Information("Setting PathBase to {PathBase}.", Cfg.SiteConfig.PathBase);
                app.UsePathBase(Cfg.SiteConfig.PathBase);
                app.UseStaticFiles(new StaticFileOptions
                {
                    RequestPath = Cfg.SiteConfig.PathBase
                });
                app.Use((context, next) =>
                {
                    if (context.Request.Path.StartsWithSegments(Cfg.SiteConfig.PathBase, out var remainder))
                    {
                        context.Request.Path = remainder;
                        context.Request.PathBase = new PathString(Cfg.SiteConfig.PathBase);
                    }
                    return next();
                });
            }
            else
            {
                app.UseStaticFiles();
            }

            if (environment == "Development")
            {
                app.UseDeveloperExceptionPage();
                // If you want saving views to not require a recompile,
                // see https://kmatyaszek.github.io/2020/02/29/how-to-enable-browser-link-in-aspnetcore3-app.html
                app.UseBrowserLink();
            }
            else
            {
                app.UseExceptionHandler("/Error");
            }
            
            
            app.UseHttpsRedirection();
            app.UseRouting();

            app.UseCookiePolicy();
            app.UseSerilogRequestLogging();
            // Must call UseAuthentication between UserRouting and UseEndpoints or will throw an error page
            app.UseAuthentication();
            app.UseAuthorization();
            if (Cfg.SiteConfig.EnableHangfire)
            {
                Log.Information("Setting up Hangfire dashboard.");
                app.UseHangfireDashboard("/hangfire", new DashboardOptions
                {
                    Authorization = new[] { new Extensions.HangfireAuthorizationFilter() },
                    AppPath = environment == "Development" ? "/" : "/sms"
                });
                app.UseHangfireDashboard();

                if (!string.IsNullOrEmpty(Cfg.SiteConfig.RefreshTargetsCron))
                    RecurringJob.AddOrUpdate<HangfireHelper>("refresh_targets",
                        h => h.RefreshTargets(), Cfg.SiteConfig.RefreshTargetsCron);
                else
                    RecurringJob.RemoveIfExists("refresh_targets");

                if (!string.IsNullOrEmpty(Cfg.SiteConfig.SendRemindersCron))
                    RecurringJob.AddOrUpdate<HangfireHelper>("reminders",
                        r => r.SendReminders(), Cfg.SiteConfig.SendRemindersCron);
                else
                    RecurringJob.RemoveIfExists("reminders");

                if (!string.IsNullOrEmpty(Cfg.SiteConfig.MakeIvrCron))
                    RecurringJob.AddOrUpdate<HangfireHelper>("ivr_reminders",
                    h => h.RunIvr(), Cfg.SiteConfig.MakeIvrCron);
                else
                    RecurringJob.RemoveIfExists("ivr_reminders");

                if (!string.IsNullOrEmpty(Cfg.SiteConfig.TwilioTasksCron))
                    RecurringJob.AddOrUpdate<HangfireHelper>("twilio_tasks",
                    h => h.RunTwilioTasks(), Cfg.SiteConfig.TwilioTasksCron);
                else
                    RecurringJob.RemoveIfExists("twilio_tasks");

                if (!string.IsNullOrEmpty(Cfg.SiteConfig.TextInviteCron))
                    RecurringJob.AddOrUpdate<HangfireHelper>("text_invitation",
                    h => h.SendTextInvitations(), Cfg.SiteConfig.TextInviteCron);
                else
                    RecurringJob.RemoveIfExists("text_invitation");

                if (!string.IsNullOrEmpty(Cfg.SiteConfig.RefreshReportsCron))
                    RecurringJob.AddOrUpdate<HangfireHelper>("refresh_reports",
                    h => h.RefreshReports(), Cfg.SiteConfig.RefreshReportsCron);
                else
                    RecurringJob.RemoveIfExists("refresh_reports");
            }

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapReverseProxy();
                endpoints.MapHub<InboundCallHub>("/hubs/callHub");
                endpoints.MapHub<InboundCallHub>("/hubs/inboundCallHub");
                endpoints.MapHub<MonitoringHub>("/hubs/monitoringHub");
                endpoints.MapHub<OutboundCallHub>($"/hubs/outboundCallHub");
                endpoints.MapControllerRoute("default", "{controller=Account}/{action=Index}/{id?}");
                endpoints.MapControllerRoute("home", "{controller=Home}/{action=Index}/{id?}");
            });

            app.UseMvc(routes => {
                routes.MapRoute(
                    name: "Default",
                    template: "{controller}/{action}/{id?}",
                    defaults: new { controller = "Home", action = "Index" }
                );
                routes.MapRoute(
                    name: "Error404",
                    template: "{*url}",
                    defaults: new { controller = "Error", action = "Handle404" }
                );
            });
        }
    }

[marcelo-g-simas]

Here's the log entry from the container showing that it is receiving the configuration value for PathBase:

May 24 22:27:57.871 | k8webdemo-xxx-xxx-sms-649858d9c-gcr9j | [01:27:57 INF] Setting PathBase to /sms.

When I try to navigate to /sms the app redirects to a path off the root and loses the /sms prefix:

/Account/Login?ReturnUrl=%2F

Where it should have redirected to

/sms/Account/Login?ReturnUrl=%2F

[halter73]

Can you do this?

var builder = WebApplication.CreateBuilder(new WebApplicationOptions
{
    ApplicationName = typeof(Program).Assembly.FullName,
    Args = args,
    EnvironmentName = environment,
    ContentRootPath = !string.IsNullOrEmpty(config.SiteConfig.PathBase) ? config.SiteConfig.PathBase : null,
});

[marcelo-g-simas]

I don't see how this would help as the docs indicate that ContentRootPath is the physical local path to the application files (i.e., config json. dlls, etc.). The property config.SiteConfig.PathBase is populated with /sms, which is the path under the website that this application is supposed to show up as.

[marcelo-g-simas]

What I am trying to deal with is an app that is hosted in a container which is exposed via an ingress in a k8s cluster under a path other than root (/sms in this case). This code around UsePathBase() used to work under .NET 3.1 when we validated our plans for going to k8s. We are now trying to actually migrate under .NET 6 and the new builder and realizing that the new style builder has this regression in it.

[marcelo-g-simas]

Anyways, I tested locally that and the page did not redirect back to the root. But all the static resources failed to load:

[marcelo-g-simas]

So it looks like this solves part of the issue, but the little dance I was around UseStaticFiles may not be working. Going to deploy this to the cluster to see what happens.

[marcelo-g-simas]

Actually, that was a false hit. I called dotnet run but forgot to hit save on the Program.cs file (using VS Code). Once I actually had the code change in place and tried to run I got this (as I'd originally expected):

Unhandled exception. System.IO.DirectoryNotFoundException: /sms/
   at Microsoft.Extensions.FileProviders.PhysicalFileProvider..ctor(String root, ExclusionFilters filters)
   at Microsoft.Extensions.FileProviders.PhysicalFileProvider..ctor(String root)
   at Microsoft.AspNetCore.Hosting.BootstrapHostBuilder.RunDefaultCallbacks(ConfigurationManager configuration, HostBuilder innerBuilder)
   at Microsoft.AspNetCore.Builder.WebApplicationBuilder..ctor(WebApplicationOptions options, Action`1 configureDefaults)
   at Microsoft.AspNetCore.Builder.WebApplication.CreateBuilder(WebApplicationOptions options)
   at SurveyManagementSystem.Program.CreateWebApplication(String[] args) in /Users/marcelosimas/Git/xxxx_hts/sms/SurveyManagementSystem/Program.cs:line 87
   at SurveyManagementSystem.Program.Main(String[] args) in /Users/marcelosimas/Git/xxxx_hts/sms/SurveyManagementSystem/Program.cs:line 21

[marcelo-g-simas]

I am going to post this on dotnet/aspnetcore#38448.

[marcelo-g-simas]

I think I figured out the issue. it was a rewrite rule in the ingress which was removing the subfolders. Once I took it all things behaved as expected, more testing is needed but this is encouraging.