Xử lý Tải

Rate Limiting

Cài đặt

dotnet add package AspNetCoreRateLimit

Cấu hình

// Program.cs
builder.Services.AddMemoryCache();
builder.Services.Configure<IpRateLimitOptions>(options =>
{
    options.EnableEndpointRateLimiting = true;
    options.StackBlockedRequests = false;
    options.GeneralRules = new List<RateLimitRule>
    {
        new RateLimitRule
        {
            Endpoint = "*",
            Period = "1m",
            Limit = 60
        },
        new RateLimitRule
        {
            Endpoint = "POST:/api/auth/login",
            Period = "1m",
            Limit = 5
        }
    };
});

builder.Services.AddInProcessMessageBus();
builder.Services.AddIpRateLimiting();

var app = builder.Build();
app.UseIpRateLimiting();

Controller

[HttpGet]
[EnableRateLimiting("PerUser")]
public IActionResult GetExpensiveData()
{
    return Ok();
}

Load Balancing

Round Robin

Request 1 → Instance 1
Request 2 → Instance 2
Request 3 → Instance 3
Request 4 → Instance 1 (loop)

Health Checks với Load Balancer

builder.Services.AddHealthChecks()
    .AddDbContextCheck<AppDbContext>("database")
    .AddRedis("localhost:6379", name: "redis");

var app = builder.Build();

// Health endpoint
app.MapHealthChecks("/health");

// Detailed health endpoint
app.MapHealthChecks("/health/detail", new HealthCheckOptions
{
    ResponseWriter = async (context, report) =>
    {
        context.ContentType = "application/json";
        await context.Response.WriteAsJsonAsync(new
        {
            status = report.Status.ToString(),
            checks = report.Entries.Select(e => new
            {
                name = e.Key,
                status = e.Value.Status.ToString(),
                description = e.Value.Description,
                duration = e.Value.Duration.TotalMilliseconds
            })
        });
    }
});

Health Checks

Basic Health Check

public class DatabaseHealthCheck : IHealthCheck
{
    private readonly AppDbContext _context;
    
    public DatabaseHealthCheck(AppDbContext context)
    {
        _context = context;
    }
    
    public async Task<HealthCheckResult> CheckHealthAsync(
        HealthCheckContext context,
        CancellationToken cancellationToken = default)
    {
        try
        {
            await _context.Database.CanConnectAsync(cancellationToken);
            return HealthCheckResult.Healthy();
        }
        catch (Exception ex)
        {
            return HealthCheckResult.Unhealthy(
                "Database connection failed", 
                ex);
        }
    }
}

Đăng ký Health Check

builder.Services.AddHealthChecks()
    .AddCheck<DatabaseHealthCheck>("database")
    .AddCheck<ExternalApiHealthCheck>("external_api")
    .AddUrlGroup(new Uri("https://api.example.com/health"), "api");