Add HealthCheck to ASP.Net Core API

1. Install package

dotnet add package Microsoft.Extensions.Diagnostics.HealthChecks

1. Create HealthCheck class

public class SqlConnectionHealthCheck : IHealthCheck
{
    private const string DefaultTestQuery = "Select 1"; public string ConnectionString { get; }
    public string TestQuery { get; }
    public SqlConnectionHealthCheck(string connectionString) : this(connectionString, testQuery: DefaultTestQuery)
    { }
    public SqlConnectionHealthCheck(string connectionString, string testQuery)
    {
        ConnectionString = connectionString ?? throw new ArgumentNullException(nameof(connectionString));
        TestQuery = testQuery;
    }
    public async Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default(CancellationToken))
    {
        using (var connection = new SqlConnection(ConnectionString))
        {
            try
            {
                await connection.OpenAsync(cancellationToken);
                if (TestQuery != null)
                {
                    var command = connection.CreateCommand();
                    command.CommandText = TestQuery;
                    await command.ExecuteNonQueryAsync(cancellationToken);
                }
            }
            catch (DbException ex)
            {
                return new HealthCheckResult(status: context.Registration.FailureStatus, exception: ex);
            }
        }
        return HealthCheckResult.Healthy();
    }
}

1. Configure startup.cs service

public void ConfigureServices(IServiceCollection services)
{
    services.AddHealthChecks()
            .AddCheck(
            "OrderingDB-check",
            new SqlConnectionHealthCheck(Configuration["ConnectionString"]), HealthStatus.Unhealthy,
            new string[] { "orderingdb" });
}

1. Map HealthCheck path

public void Configure(IApplicationBuilder app, IHostingEnvironment env) {
    app.UseEndpoints(endpoints =>
    {
        endpoints.MapHealthChecks("/hc");
    });
}

reference

• https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/health-checks?view=aspnetcore-6.0
• https://docs.microsoft.com/en-us/dotnet/architecture/microservices/