Add Database health sample

build/dependencies.props

@@ -17,6 +17,7 @@
     <MicrosoftEntityFrameworkCoreRelationalPackageVersion>2.2.0-preview1-34823</MicrosoftEntityFrameworkCoreRelationalPackageVersion>
     <MicrosoftEntityFrameworkCoreSqlServerPackageVersion>2.2.0-preview1-34823</MicrosoftEntityFrameworkCoreSqlServerPackageVersion>
     <MicrosoftExtensionsConfigurationCommandLinePackageVersion>2.2.0-preview1-34823</MicrosoftExtensionsConfigurationCommandLinePackageVersion>
+    <MicrosoftExtensionsConfigurationJsonPackageVersion>2.2.0-preview1-34823</MicrosoftExtensionsConfigurationJsonPackageVersion>
     <MicrosoftExtensionsDependencyInjectionAbstractionsPackageVersion>2.2.0-preview1-34823</MicrosoftExtensionsDependencyInjectionAbstractionsPackageVersion>
     <MicrosoftExtensionsDependencyInjectionPackageVersion>2.2.0-preview1-34823</MicrosoftExtensionsDependencyInjectionPackageVersion>
     <MicrosoftExtensionsDiagnosticAdapterPackageVersion>2.2.0-preview1-34823</MicrosoftExtensionsDiagnosticAdapterPackageVersion>
@@ -37,6 +38,7 @@
     <MoqPackageVersion>4.7.49</MoqPackageVersion>
     <NETStandardLibrary20PackageVersion>2.0.3</NETStandardLibrary20PackageVersion>
     <NewtonsoftJsonPackageVersion>11.0.2</NewtonsoftJsonPackageVersion>
+    <SystemDataSqlClientPackageVersion>4.6.0-preview1-26725-04</SystemDataSqlClientPackageVersion>
     <SystemDiagnosticsDiagnosticSourcePackageVersion>4.5.0</SystemDiagnosticsDiagnosticSourcePackageVersion>
     <SystemReflectionMetadataPackageVersion>1.6.0</SystemReflectionMetadataPackageVersion>
     <XunitPackageVersion>2.3.1</XunitPackageVersion>

samples/HealthChecksSample/DBHealthStartup.cs

@@ -0,0 +1,47 @@
+
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace HealthChecksSample
+{
+    // Pass in `--scenario db` at the command line to run this sample.
+    public class DBHealthStartup
+    {
+        public DBHealthStartup(IConfiguration configuration)
+        {
+            Configuration = configuration;
+        }
+
+        public IConfiguration Configuration { get; }
+
+        public void ConfigureServices(IServiceCollection services)
+        {
+            // Registers required services for health checks
+            services.AddHealthChecks()
+
+                // Add a health check for a SQL database
+                .AddCheck(new SqlConnectionHealthCheck("MyDatabase", Configuration["ConnectionStrings:DefaultConnection"]));
+        }
+
+        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
+        {
+            // This will register the health checks middleware at the URL /health.
+            // 
+            // By default health checks will return a 200 with 'Healthy' when the database is responsive
+            // - We've registered a SqlConnectionHealthCheck
+            // - The default response writer writes the HealthCheckStatus as text/plain content
+            //
+            // This is the simplest way to use health checks, it is suitable for systems
+            // that want to check for 'liveness' of an application with a database.
+            app.UseHealthChecks("/health");
+
+            app.Run(async (context) =>
+            {
+                await context.Response.WriteAsync("Go to /health to see the health status");
+            });
+        }
+    }
+}

samples/HealthChecksSample/DbConnectionHealthCheck.cs

@@ -0,0 +1,64 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Data.Common;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+
+namespace HealthChecksSample
+{
+    public abstract class DbConnectionHealthCheck : IHealthCheck
+    {
+        protected DbConnectionHealthCheck(string name, string connectionString)
+            : this(name, connectionString, testQuery: null)
+        {
+        }
+
+        protected DbConnectionHealthCheck(string name, string connectionString, string testQuery)
+        {
+            Name = name ?? throw new System.ArgumentNullException(nameof(name));
+            ConnectionString = connectionString ?? throw new ArgumentNullException(nameof(connectionString));
+            TestQuery = testQuery;
+        }
+
+        public string Name { get; }
+
+        protected string ConnectionString { get; }
+
+        // This sample supports specifying a query to run as a boolean test of whether the database
+        // is responding. It is important to choose a query that will return quickly or you risk
+        // overloading the database.
+        //
+        // In most cases this is not necessary, but if you find it necessary, choose a simple query such as 'SELECT 1'.
+        protected string TestQuery { get; }
+
+        protected abstract DbConnection CreateConnection(string connectionString);
+
+        public async Task<HealthCheckResult> CheckHealthAsync(CancellationToken cancellationToken = default(CancellationToken))
+        {
+            using (var connection = CreateConnection(ConnectionString))
+            {
+                try
+                {
+                    await connection.OpenAsync(cancellationToken);
+
+                    if (TestQuery != null)
+                    {
+                        var command = connection.CreateCommand();
+                        command.CommandText = TestQuery;
+
+                        await command.ExecuteNonQueryAsync(cancellationToken);
+                    }
+                }
+                catch (DbException ex)
+                {
+                    return HealthCheckResult.Unhealthy(ex);
+                }
+            }
+
+            return HealthCheckResult.Healthy();
+        }
+    }
+}

samples/HealthChecksSample/HealthChecksSample.csproj

@@ -8,10 +8,12 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Configuration.CommandLine" Version="$(MicrosoftExtensionsConfigurationCommandLinePackageVersion)" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="$(MicrosoftExtensionsConfigurationJsonPackageVersion)" />
     <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="$(MicrosoftExtensionsLoggingConsolePackageVersion)" />
     <PackageReference Include="Microsoft.AspNetCore.Server.Kestrel" Version="$(MicrosoftAspNetCoreServerKestrelPackageVersion)" />
     <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="$(MicrosoftAspNetCoreStaticFilesPackageVersion)" />
     <PackageReference Include="Newtonsoft.Json" Version="$(NewtonsoftJsonPackageVersion)" />
+    <PackageReference Include="System.Data.SqlClient" Version="$(SystemDataSqlClientPackageVersion)" />
   </ItemGroup>
 
   <ItemGroup>

samples/HealthChecksSample/Program.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Logging;
@@ -19,6 +20,7 @@ namespace HealthChecksSample
                 { "writer", typeof(CustomWriterStartup) },
                 { "liveness", typeof(LivenessProbeStartup) },
                 { "port", typeof(ManagementPortStartup) },
+                { "db", typeof(DBHealthStartup) },
             };
         }
 
@@ -30,6 +32,8 @@ namespace HealthChecksSample
         public static IWebHost BuildWebHost(string[] args)
         {
             var config = new ConfigurationBuilder()
+                .SetBasePath(Directory.GetCurrentDirectory())
+                .AddJsonFile("appsettings.json")
                 .AddEnvironmentVariables(prefix: "ASPNETCORE_")
                 .AddCommandLine(args)
                 .Build();

samples/HealthChecksSample/SqlConnectionHealthCheck.cs

@@ -0,0 +1,26 @@
+using System.Data.Common;
+using System.Data.SqlClient;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+
+namespace HealthChecksSample
+{
+    public class SqlConnectionHealthCheck : DbConnectionHealthCheck
+    {
+        private static readonly string DefaultTestQuery = "Select 1";
+
+        public SqlConnectionHealthCheck(string name, string connectionString)
+            : this(name, connectionString, testQuery: DefaultTestQuery)
+        {
+        }
+
+        public SqlConnectionHealthCheck(string name, string connectionString, string testQuery)
+            : base(name, connectionString, testQuery ?? DefaultTestQuery)
+        {
+        }
+
+        protected override DbConnection CreateConnection(string connectionString)
+        {
+            return new SqlConnection(connectionString);
+        }
+    }
+}

samples/HealthChecksSample/appsettings.json

@@ -0,0 +1,5 @@
+{
+  "ConnectionStrings": {
+    "DefaultConnection": "Server=(localdb)\\MSSQLLocalDB;Database=HealthCheckSample;Trusted_Connection=True;MultipleActiveResultSets=true;ConnectRetryCount=0"
+  }
+}