Remove private static cache from RabbitMQHealthCheck (#2343)

* Remove private static cache from RabbitMQHealthCheck

RabbitMQHealthCheck is maintaining it's private static cache of instances. It's wrong, as it can cause a memory leak (it won't ever be freed).

Moreover, it's can create instances of IConnection. This is wrong, as it can lead into a situation when we have multiple instances of IConnection that are connected to the same server: one used by the app and another created and used by the health check. And we should have only one.

We should do the same as in #2040, #2116 and #2096

I left RabbitMQ.v6 as-is to limit the breaking change. Only when an existing user moves from RabbitMQ.Client v6 to v7 will they need to update their health check (along with other breaking changes in RabbitMQ.Client).

* Add test when no IConnection is registered in DI.

src/HealthChecks.Rabbitmq.v6/DependencyInjection/RabbitMQHealthCheckBuilderExtensions.cs

@@ -0,0 +1,207 @@
+using HealthChecks.RabbitMQ;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using RabbitMQ.Client;
+
+namespace Microsoft.Extensions.DependencyInjection;
+
+/// <summary>
+/// Extension methods to configure <see cref="RabbitMQHealthCheck"/>.
+/// </summary>
+public static class RabbitMQHealthCheckBuilderExtensions
+{
+    private const string NAME = "rabbitmq";
+
+    /// <summary>
+    /// Add a health check for RabbitMQ services using connection string (amqp uri).
+    /// </summary>
+    /// <param name="builder">The <see cref="IHealthChecksBuilder"/>.</param>
+    /// <param name="rabbitConnectionString">The RabbitMQ connection string to be used.</param>
+    /// <param name="sslOption">The RabbitMQ ssl options. Optional. If <c>null</c>, the ssl option will counted as disabled and not used.</param>
+    /// <param name="name">The health check name. Optional. If <c>null</c> the type name 'rabbitmq' 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 AddRabbitMQ(
+        this IHealthChecksBuilder builder,
+        string rabbitConnectionString,
+        SslOption? sslOption = default,
+        string? name = default,
+        HealthStatus? failureStatus = default,
+        IEnumerable<string>? tags = default,
+        TimeSpan? timeout = default)
+    {
+        return builder.AddRabbitMQ(new Uri(rabbitConnectionString), sslOption, name, failureStatus, tags, timeout);
+    }
+
+    /// <summary>
+    /// Add a health check for RabbitMQ services using connection string (amqp uri).
+    /// </summary>
+    /// <param name="builder">The <see cref="IHealthChecksBuilder"/>.</param>
+    /// <param name="rabbitConnectionString">The RabbitMQ connection string to be used.</param>
+    /// <param name="sslOption">The RabbitMQ ssl options. Optional. If <c>null</c>, the ssl option will counted as disabled and not used.</param>
+    /// <param name="name">The health check name. Optional. If <c>null</c> the type name 'rabbitmq' 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 AddRabbitMQ(
+        this IHealthChecksBuilder builder,
+        Uri rabbitConnectionString,
+        SslOption? sslOption = default,
+        string? name = default,
+        HealthStatus? failureStatus = default,
+        IEnumerable<string>? tags = default,
+        TimeSpan? timeout = default)
+    {
+        var options = new RabbitMQHealthCheckOptions
+        {
+            ConnectionUri = rabbitConnectionString,
+            Ssl = sslOption
+        };
+
+        return builder.Add(new HealthCheckRegistration(
+            name ?? NAME,
+            new RabbitMQHealthCheck(options),
+            failureStatus,
+            tags,
+            timeout));
+    }
+
+    /// <summary>
+    /// Add a health check for RabbitMQ services using <see cref="IConnection"/> from service provider
+    /// or <see cref="IConnectionFactory"/> from service provider if none is found. At least one must be configured.
+    /// </summary>
+    /// <remarks>
+    /// This method shouldn't be called more than once.
+    /// Each subsequent call will create a new connection, which overrides the previous ones.
+    /// </remarks>
+    /// <param name="builder">The <see cref="IHealthChecksBuilder"/>.</param>
+    /// <param name="name">The health check name. Optional. If <c>null</c> the type name 'rabbitmq' 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 AddRabbitMQ(
+        this IHealthChecksBuilder builder,
+        string? name = default,
+        HealthStatus? failureStatus = default,
+        IEnumerable<string>? tags = default,
+        TimeSpan? timeout = default)
+    {
+        builder.Services.AddSingleton(sp =>
+        {
+            var connection = sp.GetService<IConnection>();
+            var connectionFactory = sp.GetService<IConnectionFactory>();
+
+            if (connection != null)
+            {
+                return new RabbitMQHealthCheck(new RabbitMQHealthCheckOptions { Connection = connection });
+            }
+            else if (connectionFactory != null)
+            {
+                return new RabbitMQHealthCheck(new RabbitMQHealthCheckOptions { ConnectionFactory = connectionFactory });
+            }
+            else
+            {
+                throw new ArgumentException($"Either an IConnection or IConnectionFactory must be registered with the service provider");
+            }
+        });
+
+        return builder.Add(new HealthCheckRegistration(
+            name ?? NAME,
+            sp => sp.GetRequiredService<RabbitMQHealthCheck>(),
+            failureStatus,
+            tags,
+            timeout));
+    }
+
+    /// <summary>
+    /// Add a health check for RabbitMQ services.
+    /// </summary>
+    /// <remarks>
+    /// <paramref name="setup"/> will be called each time the healthcheck route is requested. However
+    /// the created <see cref="IConnection"/> will be reused.
+    /// </remarks>
+    /// <param name="builder">The <see cref="IHealthChecksBuilder"/>.</param>
+    /// <param name="setup">The action to configure the RabbitMQ setup.</param>
+    /// <param name="name">The health check name. Optional. If <c>null</c> the type name 'rabbitmq' 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 AddRabbitMQ(
+        this IHealthChecksBuilder builder,
+        Action<RabbitMQHealthCheckOptions>? setup,
+        string? name = default,
+        HealthStatus? failureStatus = default,
+        IEnumerable<string>? tags = default,
+        TimeSpan? timeout = default)
+    {
+        var options = new RabbitMQHealthCheckOptions();
+        setup?.Invoke(options);
+
+        return builder.Add(new HealthCheckRegistration(
+            name ?? NAME,
+            new RabbitMQHealthCheck(options),
+            failureStatus,
+            tags,
+            timeout));
+    }
+
+    /// <summary>
+    /// Add a health check for RabbitMQ services.
+    /// </summary>
+    /// <remarks>
+    /// <paramref name="setup"/> will be called the first time the healthcheck route is requested. However
+    /// the created <see cref="IConnection"/> will be reused.
+    /// </remarks>
+    /// <param name="builder">The <see cref="IHealthChecksBuilder"/>.</param>
+    /// <param name="setup">The action to configure the RabbitMQ setup with <see cref="IServiceProvider"/>.</param>
+    /// <param name="name">The health check name. Optional. If <c>null</c> the type name 'rabbitmq' 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 AddRabbitMQ(
+        this IHealthChecksBuilder builder,
+        Action<IServiceProvider, RabbitMQHealthCheckOptions>? setup,
+        string? name = default,
+        HealthStatus? failureStatus = default,
+        IEnumerable<string>? tags = default,
+        TimeSpan? timeout = default)
+    {
+        var options = new RabbitMQHealthCheckOptions();
+
+        return builder.Add(new HealthCheckRegistration(
+            name ?? NAME,
+            sp =>
+            {
+                if (!options.AlreadyConfiguredByHealthCheckRegistrationCall)
+                {
+                    setup?.Invoke(sp, options);
+                    options.AlreadyConfiguredByHealthCheckRegistrationCall = true;
+                }
+
+                return new RabbitMQHealthCheck(options);
+            },
+            failureStatus,
+            tags,
+            timeout));
+    }
+}

src/HealthChecks.Rabbitmq.v6/HealthChecks.Rabbitmq.v6.csproj

@@ -14,10 +14,6 @@
     <PackageReference Include="RabbitMQ.Client" VersionOverride="[6.8.1,7.0.0)" />
 
     <Compile Include="../HealthCheckResultTask.cs" />
-    <Compile Include="../HealthChecks.Rabbitmq/DependencyInjection/RabbitMQHealthCheckBuilderExtensions.cs" Link="DependencyInjection/RabbitMQHealthCheckBuilderExtensions.cs" />
-    <Compile Include="../HealthChecks.Rabbitmq/RabbitMQHealthCheckOptions.cs" />
-
-    <None Include="../HealthChecks.Rabbitmq/README.md" Pack="true" PackagePath="\" />
   </ItemGroup>
 
 </Project>

src/HealthChecks.Rabbitmq.v6/README.md

@@ -0,0 +1,91 @@
+# RabbitMQ Health Check
+
+This health check verifies the ability to communicate with a RabbitMQ server
+
+## Example Usage
+
+With all of the following examples, you can additionally add the following parameters:
+
+- `name`: The health check name. Default if not specified is `rabbitmq`.
+- `failureStatus`: The `HealthStatus` that should be reported when the health check fails. Default is `HealthStatus.Unhealthy`.
+- `tags`: A list of tags that can be used to filter sets of health checks.
+- `timeout`: A `System.TimeSpan` representing the timeout of the check.
+
+### Basic
+
+This will create a new `IConnection` and reuse on every request to get the health check result. Use
+the extension method where you provide the `Uri` to connect with. You can optionally set the `SslOption` if needed.
+IConnection created with this option use UseBackgroundThreadsForIO by default in order to gracefully shutdown on non reference IConnection by ServiceCollection.
+
+```csharp
+public void ConfigureServices(IServiceCollection services)
+{
+    services
+        .AddHealthChecks()
+        .AddRabbitMQ(rabbitConnectionString: "amqps://user:pass@host1/vhost")
+        .AddRabbitMQ(rabbitConnectionString: "amqps://user:pass@host2/vhost");
+}
+```
+
+### Dependency Injected `IConnection`
+
+As per [RabbitMQ docs](https://www.rabbitmq.com/connections.html) and its suggestions on
+[high connectivity churn](https://www.rabbitmq.com/networking.html#dealing-with-high-connection-churn), connections are meant to be long lived.
+Ideally, this should be configured as a singleton.
+
+If you are sharing a single connection for every time a health check is requested,
+you must ensure automatic recovery is enable so that the connection can be re-established if lost.
+
+```csharp
+public void ConfigureServices(IServiceCollection services)
+{
+    services
+        .AddSingleton<IConnection>(sp =>
+        {
+            var factory = new ConnectionFactory
+            {
+                Uri = new Uri("amqps://user:pass@host/vhost"),
+                AutomaticRecoveryEnabled = true
+            };
+            return  factory.CreateConnection();
+        })
+        .AddHealthChecks()
+        .AddRabbitMQ();
+}
+```
+
+Alternatively, you can specify the connection to use with a factory function given the `IServiceProvider`.
+
+```csharp
+public void ConfigureServices(IServiceCollection services)
+{
+    services
+        .AddHealthChecks()
+        .AddRabbitMQ(sp =>
+        {
+            var factory = new ConnectionFactory
+            {
+                Uri = new Uri("amqps://user:pass@host/vhost"),
+                AutomaticRecoveryEnabled = true
+            };
+            return factory.CreateConnection();
+        });
+}
+```
+
+Or you register IConnectionFactory and then the healthcheck will create a single connection for that one.
+
+```csharp
+public void ConfigureServices(IServiceCollection services)
+{
+   services
+        .AddSingleton<IConnectionFactory>(sp =>
+            new ConnectionFactory
+            {
+                Uri = new Uri("amqps://user:pass@host/vhost"),
+                AutomaticRecoveryEnabled = true
+            })
+        .AddHealthChecks()
+        .AddRabbitMQ();
+}
+```