Added MySQL HealthChecks Query and Callback support.

src/HealthChecks.MySql/DependencyInjection/MySqlHealthCheckBuilderExtensions.cs

@@ -1,5 +1,6 @@
 using HealthChecks.MySql;
 using Microsoft.Extensions.Diagnostics.HealthChecks;
+using MySqlConnector;
 
 namespace Microsoft.Extensions.DependencyInjection;
 
@@ -9,13 +10,16 @@ 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.
+    /// Add a health check for MySQL/MariaDB Server databases.
     /// </summary>
     /// <param name="builder">The <see cref="IHealthChecksBuilder"/>.</param>
-    /// <param name="connectionString">The MySql connection string to be used.</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="connectionString">The Sql Server connection string to be used.</param>
+    /// <param name="healthQuery">The query to be executed.</param>
+    /// <param name="configure">An optional action to allow additional SQL Server specific configuration.</param>
+    /// <param name="name">The health check name. Optional. If <c>null</c> the type name 'sqlserver' 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.
@@ -26,14 +30,86 @@ public static class MySqlHealthCheckBuilderExtensions
     public static IHealthChecksBuilder AddMySql(
         this IHealthChecksBuilder builder,
         string connectionString,
+        string healthQuery = HEALTH_QUERY,
+        Action<MySqlConnection>? configure = null,
         string? name = default,
         HealthStatus? failureStatus = default,
         IEnumerable<string>? tags = default,
         TimeSpan? timeout = default)
     {
+        return builder.AddMySql(_ => connectionString, healthQuery, configure, name, failureStatus, tags, timeout);
+    }
+
+    /// <summary>
+    /// Add a health check for MySQL/MariaDB Server databases.
+    /// </summary>
+    /// <param name="builder">The <see cref="IHealthChecksBuilder"/>.</param>
+    /// <param name="connectionStringFactory">A factory to build the SQL Server connection string to use.</param>
+    /// <param name="healthQuery">The query to be executed.</param>
+    /// <param name="configure">An optional action to allow additional SQL Server specific configuration.</param>
+    /// <param name="name">The health check name. Optional. If <c>null</c> the type name 'sqlserver' 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, string> connectionStringFactory,
+        string healthQuery = HEALTH_QUERY,
+        Action<MySqlConnection>? configure = null,
+        string? name = default,
+        HealthStatus? failureStatus = default,
+        IEnumerable<string>? tags = default,
+        TimeSpan? timeout = default)
+    {
+        Guard.ThrowIfNull(connectionStringFactory);
+
+        return builder.Add(new HealthCheckRegistration(
+            name ?? NAME,
+            sp =>
+            {
+                var options = new MySqlHealthCheckOptions
+                {
+                    ConnectionString = connectionStringFactory(sp),
+                    CommandText = healthQuery,
+                    Configure = configure,
+                };
+                return new MySqlHealthCheck(options);
+            },
+            failureStatus,
+            tags,
+            timeout));
+    }
+
+    /// <summary>
+    /// Add a health check for MySQL/MariaDB Server databases.
+    /// </summary>
+    /// <param name="builder">The <see cref="IHealthChecksBuilder"/>.</param>
+    /// <param name="options">Options for health check.</param>
+    /// <param name="name">The health check name. Optional. If <c>null</c> the type name 'sqlserver' 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,
+        MySqlHealthCheckOptions options,
+        string? name = default,
+        HealthStatus? failureStatus = default,
+        IEnumerable<string>? tags = default,
+        TimeSpan? timeout = default)
+    {
+        Guard.ThrowIfNull(options);
+
         return builder.Add(new HealthCheckRegistration(
             name ?? NAME,
-            _ => new MySqlHealthCheck(connectionString),
+            _ => new MySqlHealthCheck(options),
             failureStatus,
             tags,
             timeout));

src/HealthChecks.MySql/MySqlHealthCheck.cs

@@ -8,24 +8,38 @@ namespace HealthChecks.MySql;
 /// </summary>
 public class MySqlHealthCheck : IHealthCheck
 {
-    private readonly string _connectionString;
+    private readonly MySqlHealthCheckOptions _options;
 
-    public MySqlHealthCheck(string connectionString)
+    public MySqlHealthCheck(MySqlHealthCheckOptions options)
     {
-        _connectionString = Guard.ThrowIfNull(connectionString);
+        Guard.ThrowIfNull(options.ConnectionString, true);
+        Guard.ThrowIfNull(options.CommandText, true);
+        _options = options;
     }
 
     /// <inheritdoc />
     public async Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
     {
         try
         {
-            using var connection = new MySqlConnection(_connectionString);
+            using var connection = new MySqlConnection(_options.ConnectionString);
 
             await connection.OpenAsync(cancellationToken).ConfigureAwait(false);
 
+            using var command = connection.CreateCommand();
+
+            command.CommandText = _options.CommandText;
+
+            object? result = await command
+                .ExecuteScalarAsync(cancellationToken)
+                .ConfigureAwait(false);
+
+            var returnQueryResults =
+                _options.HealthCheckResultBuilder?
+                    .Invoke(result) ?? HealthCheckResult.Healthy();
+
             return await connection.PingAsync(cancellationToken).ConfigureAwait(false)
-                ? HealthCheckResult.Healthy()
+                ? returnQueryResults
                 : new HealthCheckResult(context.Registration.FailureStatus, description: $"The {nameof(MySqlHealthCheck)} check fail.");
         }
         catch (Exception ex)

src/HealthChecks.MySql/MySqlHealthCheckOptions.cs

@@ -0,0 +1,31 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using MySqlConnector;
+
+namespace HealthChecks.MySql;
+
+/// <summary>
+/// Options for <see cref="MySqlHealthCheck"/>.
+/// </summary>
+public class MySqlHealthCheckOptions
+{
+    /// <summary>
+    /// The MySQL Server connection string to be used.
+    /// </summary>
+    public string ConnectionString { get; set; } = null!;
+
+    /// <summary>
+    /// The query to be executed.
+    /// </summary>
+    public string CommandText { get; set; } = MySqlHealthCheckBuilderExtensions.HEALTH_QUERY;
+
+    /// <summary>
+    /// An optional action executed before the connection is opened in the health check.
+    /// </summary>
+    public Action<MySqlConnection>? Configure { get; set; }
+
+    /// <summary>
+    /// An optional delegate to build health check result.
+    /// </summary>
+    public Func<object?, HealthCheckResult>? HealthCheckResultBuilder { get; set; }
+}