如何在ASP.NET核心运行状况检查中注入依赖项

我可以添加实现该Microsoft.Extensions.Diagnostics.HealthChecks.IHealthCheck接口的自定义检查.但是因为我需要向AddCheck方法提供实例而不是类型,并且需要在ConfigureServices方法内部运行,所以我不能在自定义检查器中注入任何依赖项.

有没有办法解决这个问题？

简答

如何在ASP.NET核心运行状况检查中注入依赖项.

如果我们以正确的顺序注册我们的服务,那么SomeDependency将可以注入SomeHealthCheck构造函数,并将SomeHealthCheck作为运行状况检查功能的一部分运行.

public void ConfigureServices(IServiceCollection services)
{
    services.AddHealthChecks();
    services.AddSingleton();

    // register the custom health check 
    // after AddHealthChecks and after SomeDependency 
    services.AddSingleton();
}

更多细节

一个健康检查样品中评论说:

所有IHealthCheck服务都可用于健康检查服务和中间件.我们建议将所有健康检查注册为Singleton服务.

完整样本

using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Diagnostics.HealthChecks;

public class SomeDependency
{
    public string GetMessage() => "Hello from SomeDependency";
}

public class SomeHealthCheck : IHealthCheck
{
    public string Name => nameof(SomeHealthCheck);

    private readonly SomeDependency someDependency;

    public SomeHealthCheck(SomeDependency someDependency)
    {
        this.someDependency = someDependency;
    }

    public Task CheckHealthAsync(
        CancellationToken cancellatiOnToken= default(CancellationToken))
    {
        var message = this.someDependency.GetMessage();
        var result = new HealthCheckResult(HealthCheckStatus.Failed, null, null, null);
        return Task.FromResult(result);
    }
}

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddHealthChecks();
        services.AddSingleton();
        services.AddSingleton();
    }

    public void Configure(IApplicationBuilder app)
    {
        app.UseHealthChecks("/healthz");
        app.Run(async (context) => await context.Response.WriteAsync("Hello World!"));
    }
}

此示例也可以在GitHub上找到.