Merge pull request #1209 from riganti/health-checks

Add IHeathCheck implementation to Asp.Net Core hosting

src/Framework/Framework/Compilation/DefaultControlBuilderFactory.cs

@@ -60,6 +60,7 @@ public DefaultControlBuilderFactory(DotvvmConfiguration configuration, IMarkupFi
         /// </summary>
         private (ControlBuilderDescriptor, Lazy<IControlBuilder>) CreateControlBuilder(MarkupFile file)
         {
+            var compilationService = configuration.ServiceProvider.GetService<IDotvvmViewCompilationService>();
             void editCompilationException(DotvvmCompilationException ex)
             {
                 if (ex.FileName == null)
@@ -90,11 +91,18 @@ void editCompilationException(DotvvmCompilationException ex)
                             configuration.Resources.RegisterViewModuleResources(import, init);
                         }
 
+                        compilationService.RegisterCompiledView(file.FileName, descriptor, null);
                         return result;
                     }
                     catch (DotvvmCompilationException ex)
                     {
                         editCompilationException(ex);
+                        compilationService.RegisterCompiledView(file.FileName, descriptor, ex);
+                        throw;
+                    }
+                    catch (Exception ex)
+                    {
+                        compilationService.RegisterCompiledView(file.FileName, descriptor, ex);
                         throw;
                     }
                 });
@@ -111,6 +119,12 @@ void editCompilationException(DotvvmCompilationException ex)
             catch (DotvvmCompilationException ex)
             {
                 editCompilationException(ex);
+                compilationService.RegisterCompiledView(file.FileName, null, ex);
+                throw;
+            }
+            catch (Exception ex)
+            {
+                compilationService.RegisterCompiledView(file.FileName, null, ex);
                 throw;
             }
         }

src/Framework/Framework/Compilation/DotvvmViewCompilationService.cs

@@ -9,6 +9,7 @@
 using DotVVM.Framework.Configuration;
 using DotVVM.Framework.Controls.Infrastructure;
 using Microsoft.Extensions.DependencyInjection;
+using DotVVM.Framework.Utils;
 
 namespace DotVVM.Framework.Compilation
 {
@@ -155,10 +156,9 @@ public bool BuildView(DotHtmlFileInfo file, out DotHtmlFileInfo? masterPage)
                     using var scopedServiceProvider = dotvvmConfiguration.ServiceProvider.CreateScope(); // dependencies that are configured as scoped cannot be resolved from root service provider
                     var compiledControl = pageBuilder.builder.Value.BuildControl(controlBuilderFactory, scopedServiceProvider.ServiceProvider);
 
-                    if (compiledControl is DotvvmView view &&
-                        view.Directives!.TryGetValue(ParserConstants.MasterPageDirective, out var masterPagePath))
+                    if (pageBuilder.descriptor.MasterPage is { FileName: {} masterPagePath })
                     {
-                        masterPage = masterPages.Value.GetOrAdd(masterPagePath, new DotHtmlFileInfo(masterPagePath));
+                        masterPage = masterPages.Value.GetOrAdd(masterPagePath, path => new DotHtmlFileInfo(path));
                     }
 
                     file.Status = CompilationState.CompletedSuccessfully;
@@ -173,5 +173,30 @@ public bool BuildView(DotHtmlFileInfo file, out DotHtmlFileInfo? masterPage)
             }
             return true;
         }
+
+        /// <summary> Callback from the compiler which adds the view compilation result to the status page. </summary>
+        public void RegisterCompiledView(string file, ViewCompiler.ControlBuilderDescriptor? descriptor, Exception? exception)
+        {
+            var fileInfo =
+                routes.Value.FirstOrDefault(t => t.VirtualPath == file) ??
+                controls.Value.FirstOrDefault(t => t.VirtualPath == file) ??
+                masterPages.Value.GetOrAdd(file, path => new DotHtmlFileInfo(path));
+
+            if (exception is null)
+            {
+                fileInfo.Status = CompilationState.CompletedSuccessfully;
+                fileInfo.Exception = null;
+            }
+            else
+            {
+                fileInfo.Status = CompilationState.CompilationFailed;
+                fileInfo.Exception = exception.Message;
+            }
+
+            if (descriptor?.MasterPage is { FileName: {} masterPagePath })
+            {
+                masterPages.Value.GetOrAdd(masterPagePath, path => new DotHtmlFileInfo(path));
+            }
+        }
     }
 }

src/Framework/Framework/Compilation/IDotvvmViewCompilationService.cs

@@ -1,4 +1,5 @@
-using System.Collections.Concurrent;
+using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Threading.Tasks;
@@ -43,5 +44,7 @@ public interface IDotvvmViewCompilationService
         /// <param name="forceRecompile">If set, than everything will be recompiled.</param>
         /// <returns>Returns whether compilation was successful.</returns>
         Task<bool> CompileAll(bool buildInParallel=true, bool forceRecompile = false);
+
+        void RegisterCompiledView(string filePath, ViewCompiler.ControlBuilderDescriptor? descriptor, Exception? exception);
     }
 }

src/Framework/Hosting.AspNetCore/DotVVM.Framework.Hosting.AspNetCore.csproj

@@ -32,5 +32,7 @@
     <PackageReference Include="Microsoft.AspNetCore.Localization" Version="2.2.0" />
     <PackageReference Include="Microsoft.Extensions.Caching.Memory" Version="2.2.0" />
     <PackageReference Include="Microsoft.Extensions.Localization" Version="2.2.0" />
+    <PackageReference Include="Microsoft.AspNetCore.Diagnostics.HealthChecks" Version="2.2.0" />
+    <PackageReference Include="Microsoft.Extensions.Diagnostics.HealthChecks.Abstractions" Version="2.2.0" />
   </ItemGroup>
 </Project>

src/Framework/Hosting.AspNetCore/Hosting/DotvvmHealthCheck.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using DotVVM.Framework.Compilation;
+using DotVVM.Framework.Configuration;
+using DotVVM.Framework.Utils;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+
+namespace DotVVM.Framework.Hosting
+{
+    public class DotvvmHealthCheck : IHealthCheck
+    {
+        private readonly IDotvvmViewCompilationService compilationService;
+        private readonly DotvvmConfiguration configuration;
+
+        public DotvvmHealthCheck(
+            IDotvvmViewCompilationService compilationService,
+            DotvvmConfiguration configuration
+        )
+        {
+            this.compilationService = compilationService;
+            this.configuration = configuration;
+        }
+
+        public Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
+        {
+            var c = compilationService.GetRoutes().AddRange(compilationService.GetControls().AddRange(compilationService.GetMasterPages()));
+
+            if (!c.Any(p => p.Status == CompilationState.CompilationFailed))
+            {
+                return Task.FromResult(new HealthCheckResult(HealthStatus.Healthy));
+            }
+
+            // if nothing compiles, we say unhealthy. If at least something works, we say only degraded
+            var state =
+                c.Any(p => p.Status is CompilationState.CompletedSuccessfully or CompilationState.CompilationWarning)
+                    ? HealthStatus.Degraded
+                    : HealthStatus.Unhealthy;
+
+            var views = c.Where(p => p.Status == CompilationState.CompilationFailed)
+                         .Select(c => c.VirtualPath);
+            var statusPageUrl = configuration.Diagnostics.CompilationPage.Url;
+            return Task.FromResult(new HealthCheckResult(state, $"Dothtml pages can not be compiled: {views.Take(10).StringJoin(", ")}. See {statusPageUrl} for more information."));
+        }
+
+        public static void RegisterHealthCheck(IServiceCollection services)
+        {
+            services.ConfigureWithServices<HealthCheckServiceOptions>((options, s) => {
+                if (options.Registrations.Any(c => c.Name == "DotVVM"))
+                    return;
+
+                options.Registrations.Add(
+                    new HealthCheckRegistration(
+                        "DotVVM",
+                        ActivatorUtilities.CreateInstance<DotvvmHealthCheck>(s),
+                        null,
+                        new [] { "dotvvm" }
+                    )
+                );
+            });
+        }
+    }
+}

src/Framework/Hosting.AspNetCore/ServiceCollectionExtensions.cs

@@ -88,6 +88,8 @@ private static void AddDotVVMServices(IServiceCollection services)
             services.AddTransient<IDotvvmWarningSink, AspNetCoreLoggerWarningSink>();
 
             services.TryAddSingleton<IStartupTracer>(startupTracer);
+
+            DotvvmHealthCheck.RegisterHealthCheck(services);
         }
     }
 }

src/Samples/AspNetCoreLatest/Startup.cs

@@ -50,6 +50,8 @@ public void ConfigureServices(IServiceCollection services)
             services.AddAuthentication("Scheme3")
                 .AddCookie("Scheme3");
 
+            services.AddHealthChecks();
+
             services.AddLocalization(o => o.ResourcesPath = "Resources");
 
             services.AddDotVVM<DotvvmServiceConfigurator>();
@@ -78,11 +80,14 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILoggerF
                 }
             });
 
-
 #if AssertConfiguration
             // this compilation symbol is set by CI server
             config.AssertConfigurationIsValid();
 #endif
+            app.UseRouting();
+            app.UseEndpoints(endpoints => {
+                endpoints.MapHealthChecks("/health");
+            });
             app.UseStaticFiles();
 
             app.UseEndpoints(endpoints => {