Use MySqlDataSource in AddMySql by default

src/HealthChecks.MySql/DependencyInjection/MySqlHealthCheckBuilderExtensions.cs

@@ -10,14 +10,51 @@ namespace Microsoft.Extensions.DependencyInjection;
 public static class MySqlHealthCheckBuilderExtensions
 {
     private const string NAME = "mysql";
-    internal const string HEALTH_QUERY = "SELECT 1;";
+
+    /// <summary>
+    /// Add a health check for MySQL databases.
+    /// </summary>
+    /// <param name="builder">The <see cref="IHealthChecksBuilder"/>.</param>
+    /// <param name="dataSourceFactory">An optional factory to create the <see cref="MySqlDataSource"/>. By default, one will be retrieved from the service collection.</param>
+    /// <param name="healthQuery">The optional query to be executed. If this is <c>null</c>, a MySQL "ping" packet will be sent to the server instead of a query.</param>
+    /// <param name="configure">An optional action to allow additional MySQL specific configuration.</param>
+    /// <param name="name">The health check name. Optional. If <c>null</c> the type name 'mysql' will be used for the name.</param>
+    /// <param name="failureStatus">
+    /// The <see cref="HealthStatus"/> that should be reported when the health check fails. Optional. If <c>null</c> then
+    /// the default status of <see cref="HealthStatus.Unhealthy"/> will be reported.
+    /// </param>
+    /// <param name="tags">A list of tags that can be used to filter sets of health checks. Optional.</param>
+    /// <param name="timeout">An optional <see cref="TimeSpan"/> representing the timeout of the check.</param>
+    /// <returns>The specified <paramref name="builder"/>.</returns>
+    public static IHealthChecksBuilder AddMySql(
+        this IHealthChecksBuilder builder,
+        Func<IServiceProvider, MySqlDataSource>? dataSourceFactory = null,
+        string? healthQuery = null,
+        Action<MySqlConnection>? configure = null,
+        string? name = default,
+        HealthStatus? failureStatus = default,
+        IEnumerable<string>? tags = default,
+        TimeSpan? timeout = default)
+    {
+        return builder.Add(new HealthCheckRegistration(
+            name ?? NAME,
+            sp => new MySqlHealthCheck(new()
+            {
+                DataSource = dataSourceFactory?.Invoke(sp) ?? sp.GetRequiredService<MySqlDataSource>(),
+                CommandText = healthQuery,
+                Configure = configure,
+            }),
+            failureStatus,
+            tags,
+            timeout));
+    }
 
     /// <summary>
     /// Add a health check for MySQL databases.
     /// </summary>
     /// <param name="builder">The <see cref="IHealthChecksBuilder"/>.</param>
     /// <param name="connectionString">The MySQL connection string to be used.</param>
-    /// <param name="healthQuery">The query to be executed.</param>
+    /// <param name="healthQuery">The optional query to be executed. If this is <c>null</c>, a MySQL "ping" packet will be sent to the server instead of a query.</param>
     /// <param name="configure">An optional action to allow additional MySQL specific configuration.</param>
     /// <param name="name">The health check name. Optional. If <c>null</c> the type name 'mysql' will be used for the name.</param>
     /// <param name="failureStatus">
@@ -30,7 +67,7 @@ public static class MySqlHealthCheckBuilderExtensions
     public static IHealthChecksBuilder AddMySql(
         this IHealthChecksBuilder builder,
         string connectionString,
-        string healthQuery = HEALTH_QUERY,
+        string? healthQuery = null,
         Action<MySqlConnection>? configure = null,
         string? name = default,
         HealthStatus? failureStatus = default,
@@ -45,7 +82,7 @@ public static IHealthChecksBuilder AddMySql(
     /// </summary>
     /// <param name="builder">The <see cref="IHealthChecksBuilder"/>.</param>
     /// <param name="connectionStringFactory">A factory to build the MySQL connection string to use.</param>
-    /// <param name="healthQuery">The query to be executed.</param>
+    /// <param name="healthQuery">The optional query to be executed. If this is <c>null</c>, a MySQL "ping" packet will be sent to the server instead of a query.</param>
     /// <param name="configure">An optional action to allow additional MySQL specific configuration.</param>
     /// <param name="name">The health check name. Optional. If <c>null</c> the type name 'mysql' will be used for the name.</param>
     /// <param name="failureStatus">
@@ -58,7 +95,7 @@ public static IHealthChecksBuilder AddMySql(
     public static IHealthChecksBuilder AddMySql(
         this IHealthChecksBuilder builder,
         Func<IServiceProvider, string> connectionStringFactory,
-        string healthQuery = HEALTH_QUERY,
+        string? healthQuery = null,
         Action<MySqlConnection>? configure = null,
         string? name = default,
         HealthStatus? failureStatus = default,

src/HealthChecks.MySql/HealthChecks.MySql.csproj

@@ -8,7 +8,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="MySqlConnector" Version="2.2.7" />
+    <PackageReference Include="MySqlConnector" Version="2.3.1" />
     <PackageReference Include="Microsoft.Extensions.Diagnostics.HealthChecks" Version="7.0.9" />
   </ItemGroup>
 

src/HealthChecks.MySql/MySqlHealthCheck.cs

@@ -12,8 +12,11 @@ public class MySqlHealthCheck : IHealthCheck
 
     public MySqlHealthCheck(MySqlHealthCheckOptions options)
     {
-        Guard.ThrowIfNull(options.ConnectionString, true);
-        Guard.ThrowIfNull(options.CommandText, true);
+        Guard.ThrowIfNull(options);
+        if (options.DataSource is null && options.ConnectionString is null)
+            throw new InvalidOperationException("One of options.DataSource or options.ConnectionString must be specified.");
+        if (options.DataSource is not null && options.ConnectionString is not null)
+            throw new InvalidOperationException("Only one of options.DataSource or options.ConnectionString must be specified.");
         _options = options;
     }
 
@@ -22,18 +25,30 @@ public async Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context
     {
         try
         {
-            using var connection = new MySqlConnection(_options.ConnectionString);
+            using var connection = _options.DataSource is not null ?
+                _options.DataSource.CreateConnection() :
+                new MySqlConnection(_options.ConnectionString);
 
             _options.Configure?.Invoke(connection);
             await connection.OpenAsync(cancellationToken).ConfigureAwait(false);
 
-            using var command = connection.CreateCommand();
-            command.CommandText = _options.CommandText;
-            object? result = await command.ExecuteScalarAsync(cancellationToken).ConfigureAwait(false);
+            if (_options.CommandText is { } commandText)
+            {
+                using var command = connection.CreateCommand();
+                command.CommandText = _options.CommandText;
+                object? result = await command.ExecuteScalarAsync(cancellationToken).ConfigureAwait(false);
 
-            return _options.HealthCheckResultBuilder == null
-                ? HealthCheckResult.Healthy()
-                : _options.HealthCheckResultBuilder(result);
+                return _options.HealthCheckResultBuilder == null
+                    ? HealthCheckResult.Healthy()
+                    : _options.HealthCheckResultBuilder(result);
+            }
+            else
+            {
+                var success = await connection.PingAsync(cancellationToken).ConfigureAwait(false);
+                return _options.HealthCheckResultBuilder is null
+                    ? (success ? HealthCheckResult.Healthy() : new HealthCheckResult(context.Registration.FailureStatus)) :
+                    _options.HealthCheckResultBuilder(success);
+            }
         }
         catch (Exception ex)
         {

src/HealthChecks.MySql/MySqlHealthCheckOptions.cs

@@ -1,4 +1,3 @@
-using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Diagnostics.HealthChecks;
 using MySqlConnector;
 
@@ -10,14 +9,19 @@ namespace HealthChecks.MySql;
 public class MySqlHealthCheckOptions
 {
     /// <summary>
-    /// The MySQL connection string to be used.
+    /// The MySQL data source to be used. This is the preferred way to specify the MySQL server to be checked.
     /// </summary>
-    public string ConnectionString { get; set; } = null!;
+    public MySqlDataSource? DataSource { get; set; }
+
+    /// <summary>
+    /// The MySQL connection string to be used, if <see cref="DataSource"/> isn't set.
+    /// </summary>
+    public string? ConnectionString { get; set; }
 
     /// <summary>
     /// The query to be executed.
     /// </summary>
-    public string CommandText { get; set; } = MySqlHealthCheckBuilderExtensions.HEALTH_QUERY;
+    public string? CommandText { get; set; }
 
     /// <summary>
     /// An optional action executed before the connection is opened in the health check.

test/HealthChecks.MySql.Tests/DependencyInjection/RegistrationTests.cs

@@ -1,3 +1,5 @@
+using MySqlConnector;
+
 namespace HealthChecks.MySql.Tests.DependencyInjection;
 
 public class mysql_registration_should
@@ -18,6 +20,7 @@ public void add_health_check_when_properly_configured()
         registration.Name.ShouldBe("mysql");
         check.ShouldBeOfType<MySqlHealthCheck>();
     }
+
     [Fact]
     public void add_named_health_check_when_properly_configured()
     {
@@ -34,4 +37,22 @@ public void add_named_health_check_when_properly_configured()
         registration.Name.ShouldBe("my-mysql-group");
         check.ShouldBeOfType<MySqlHealthCheck>();
     }
+
+    [Fact]
+    public void add_health_check_for_data_source()
+    {
+        var services = new ServiceCollection();
+        services
+            .AddMySqlDataSource("Server=example")
+            .AddHealthChecks().AddMySql();
+
+        using var serviceProvider = services.BuildServiceProvider();
+        var options = serviceProvider.GetRequiredService<IOptions<HealthCheckServiceOptions>>();
+
+        var registration = options.Value.Registrations.First();
+        var check = registration.Factory(serviceProvider);
+
+        registration.Name.ShouldBe("mysql");
+        check.ShouldBeOfType<MySqlHealthCheck>();
+    }
 }

test/HealthChecks.MySql.Tests/Functional/MySqlHealthCheckTests.cs

@@ -1,11 +1,39 @@
 using System.Net;
+using MySqlConnector;
 
 namespace HealthChecks.MySql.Tests.Functional;
 
 public class mysql_healthcheck_should
 {
     [Fact]
-    public async Task be_healthy_when_mysql_server_is_available()
+    public async Task be_healthy_when_mysql_server_is_available_using_data_source()
+    {
+        var connectionString = "server=localhost;port=3306;database=information_schema;uid=root;password=Password12!";
+
+        var webHostBuilder = new WebHostBuilder()
+            .ConfigureServices(services =>
+            {
+                services
+                    .AddMySqlDataSource(connectionString)
+                    .AddHealthChecks().AddMySql(tags: new string[] { "mysql" });
+            })
+            .Configure(app =>
+            {
+                app.UseHealthChecks("/health", new HealthCheckOptions
+                {
+                    Predicate = r => r.Tags.Contains("mysql")
+                });
+            });
+
+        using var server = new TestServer(webHostBuilder);
+
+        using var response = await server.CreateRequest("/health").GetAsync().ConfigureAwait(false);
+
+        response.StatusCode.ShouldBe(HttpStatusCode.OK);
+    }
+
+    [Fact]
+    public async Task be_healthy_when_mysql_server_is_available_using_connection_string()
     {
         var connectionString = "server=localhost;port=3306;database=information_schema;uid=root;password=Password12!";
 

test/HealthChecks.MySql.Tests/HealthChecks.MySql.Tests.csproj

@@ -4,6 +4,10 @@
     <TargetFrameworks>net6.0;net7.0</TargetFrameworks>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="MySqlConnector.DependencyInjection" Version="2.3.1" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\..\src\HealthChecks.MySql\HealthChecks.MySql.csproj" />
   </ItemGroup>