app.MapHealthChecks("/health", new HealthCheckOptions
{
    ResponseWriter = async (ctx, report) =>
    {
        ctx.Response.ContentType = "application/json";
        var result = new
        {
            status = report.Status.ToString(),
            checks = report.Entries.Select(e => new
            {
                e.Key,
                e.Value.Status.ToString(),
                e.Value.Description,
                duration = e.Value.Duration.TotalMilliseconds
            })
        };
        await ctx.Response.WriteAsync(JsonSerializer.Serialize(result));
    }
});