Make it optional to register HealthCheckPublisherHostedService when using AddHealthChecks

[tobiaswatzek]

Is your feature request related to a problem? Please describe.

I am trying to use the Microsoft.Extensions.Diagnostics.HealthChecks library in a project but I don't want to register the default HealthCheckPublisherHostedService which is automatically registered when the AddHealthChecks extension method is used. I still would like to use the DefaultHealthCheckService and the HealthChecksBuilder which unfortunately are all marked as internal which means that I would have to implement them again in my code.

What I want to do is running my health checks manually with the help of the DefaultHealthCheckService inside of an Orleans cluster. The reason why I don't want to register the HealthCheckPublisherHostedService is that it would execute and publish all health checks on each node periodically which is unnecessary.

Describe the solution you'd like

I would like a method similar to AddHealthChecks or a parameter for AddHealthChecks to control if the HealthCheckPublisherHostedService gets registered or not.

Additional context

The corresponding code which registers the HealthCheckPublisherHostedService can be found here:

aspnetcore/src/HealthChecks/HealthChecks/src/DependencyInjection/HealthCheckServiceCollectionExtensions.cs

Line 29 in 7a2b820

services.TryAddEnumerable(ServiceDescriptor.Singleton<IHostedService, HealthCheckPublisherHostedService>());

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[pranavkm]

@spitzfaust we'll consider adding this API in a later release. In the meanwhile, you should be able to workaround this by invoking AddHealthCheckService on a temp IServiceCollection and cherry-pick everything but the hosted service in to the default one.

var temp = new ServiceCollection();
temp.AddHealthChecks();

foreach (var descriptor in temp)
{
    if (descriptor.ServiceType != typeof(IHostedService))
    {
        services.Add(descriptor);
    }
}

[tobiaswatzek]

@pranavkm thank you for your reply and the proposed workaround 👍

[ShreyasJejurkar]

As per my knowledge and understanding, there can be two ways to address this problem.

1. Add a optional boolean registerHealthPublisherHostedService parameter to HealthCheckServiceCollectionExtensions.AddHealthChecks and based on that we can register HostedService, by default the value will be true to avoid breaking change!

public static IHealthChecksBuilder AddHealthChecks(this IServiceCollection services, bool registerHealthPublisherHostedService = true)
{
}

2. Problem with the above approach what I think, is like going forward if we need to add more configurable settings for user, then it would be a nightmare and code smell to have a bunch of optional parameters to the given method AddHealthChecks.
   To address that we can have another option class for HealthCheck, not sure what we name it as there is already HealthCheckOptions class in the system. That way we can add more properties to that class and can make it configurable.

// omitting other overloads here
public static IHealthChecksBuilder AddHealthChecks(this IServiceCollection services, Action<someHealthCheckOptionsClassName> setupAction) 
{
}

Usage

services.AddHealthChecks((options) => {
 options.RegisterHealthPublisherHostedService  = false // defaults to true
});

2nd approach is doable, but I am not sure about the options class name and also will it make sense to add another class for configuring HealthChecks, given the fact that we already have one class for such! As per my knowledge, we cannot add a new property to current HealthCheck options to address this issue, because we cannot access HealthCheckOptions because that option is yet to configure because we do that in the middleware pipeline.

Not sure if creatingScope inside UseHealthCheck() method and adding HealthCheckPublisherHostedService to serviceCollection based on new parameter insider HealthCheckOptions will be a recommended way or not!

[Temppus]

Same here. I would like to use only default DefaultHealthCheckService registration but do not want to register HealthCheckPublisherHostedService. We are having .net core background worker service which is not asp net core based and we want to expose health check endpoints and use current default implementation for HealthCheckService.