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7. Integración de Azure OpenAI en Aplicaciones .NET

Por David Cantón

aprende a integrar Azure OpenAI en aplicaciones .NET con Semantic Kernel y Azure.AI.OpenAI: configuración, credenciales seguras, DI, streaming, rate limiting, retries, monitoreo y caché.

Introducción

Azure OpenAI Service proporciona acceso a modelos avanzados de IA como GPT-4 a través de APIs REST. En este tutorial aprenderás a integrar Azure OpenAI en aplicaciones .NET de forma segura y escalable.

Configuración Inicial

Requisitos Previos

  1. Suscripción de Azure activa
  2. Recurso Azure OpenAI creado
  3. Modelos desplegados (GPT-4, GPT-3.5-Turbo, embeddings)
  4. .NET 6.0 o superior

Obtener Credenciales

En el portal de Azure, necesitas:

Endpoint: https://tu-recurso.openai.azure.com/
API Key: tu-clave-api
Deployment Names: 
  - gpt-4
  - gpt-35-turbo
  - text-embedding-ada-002

Instalación de Paquetes

dotnet add package Azure.AI.OpenAI
dotnet add package Microsoft.SemanticKernel
dotnet add package Microsoft.Extensions.Configuration
dotnet add package Microsoft.Extensions.Configuration.UserSecrets

Gestión Segura de Credenciales

User Secrets (Desarrollo)

dotnet user-secrets init
dotnet user-secrets set "AzureOpenAI:Endpoint" "https://tu-recurso.openai.azure.com/"
dotnet user-secrets set "AzureOpenAI:ApiKey" "tu-clave-api"
dotnet user-secrets set "AzureOpenAI:ChatDeployment" "gpt-4"
dotnet user-secrets set "AzureOpenAI:EmbeddingDeployment" "text-embedding-ada-002"

Configuration en appsettings.json

{
  "AzureOpenAI": {
    "Endpoint": "",
    "ApiKey": "",
    "ChatDeployment": "gpt-4",
    "EmbeddingDeployment": "text-embedding-ada-002",
    "MaxRetries": 3,
    "TimeoutSeconds": 120
  }
}

Modelo de Configuración

public class AzureOpenAIOptions
{
    public const string SectionName = "AzureOpenAI";
    
    public required string Endpoint { get; set; }
    public required string ApiKey { get; set; }
    public required string ChatDeployment { get; set; }
    public required string EmbeddingDeployment { get; set; }
    public int MaxRetries { get; set; } = 3;
    public int TimeoutSeconds { get; set; } = 120;
}

Configuración con Dependency Injection

Startup/Program.cs

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Configuration;
using Microsoft.SemanticKernel;

var builder = WebApplication.CreateBuilder(args);

// Configurar opciones
builder.Services.Configure<AzureOpenAIOptions>(
    builder.Configuration.GetSection(AzureOpenAIOptions.SectionName));

// Registrar HttpClient configurado
builder.Services.AddHttpClient("AzureOpenAI", (serviceProvider, client) =>
{
    var options = serviceProvider
        .GetRequiredService<IOptions<AzureOpenAIOptions>>()
        .Value;
    
    client.Timeout = TimeSpan.FromSeconds(options.TimeoutSeconds);
});

// Registrar Semantic Kernel
builder.Services.AddScoped<Kernel>(serviceProvider =>
{
    var options = serviceProvider
        .GetRequiredService<IOptions<AzureOpenAIOptions>>()
        .Value;
    
    var httpClientFactory = serviceProvider
        .GetRequiredService<IHttpClientFactory>();
    
    var httpClient = httpClientFactory.CreateClient("AzureOpenAI");
    
    var kernelBuilder = Kernel.CreateBuilder();
    
    kernelBuilder.AddAzureOpenAIChatCompletion(
        deploymentName: options.ChatDeployment,
        endpoint: options.Endpoint,
        apiKey: options.ApiKey,
        httpClient: httpClient);
    
    kernelBuilder.AddAzureOpenAITextEmbeddingGeneration(
        deploymentName: options.EmbeddingDeployment,
        endpoint: options.Endpoint,
        apiKey: options.ApiKey,
        httpClient: httpClient);
    
    return kernelBuilder.Build();
});

var app = builder.Build();

Cliente Azure OpenAI Nativo

Usando Azure.AI.OpenAI

using Azure;
using Azure.AI.OpenAI;

public class AzureOpenAIClient
{
    private readonly OpenAIClient _client;
    private readonly string _chatDeployment;
    private readonly string _embeddingDeployment;
    private readonly ILogger<AzureOpenAIClient> _logger;
    
    public AzureOpenAIClient(
        IOptions<AzureOpenAIOptions> options,
        ILogger<AzureOpenAIClient> logger)
    {
        var config = options.Value;
        
        _client = new OpenAIClient(
            new Uri(config.Endpoint),
            new AzureKeyCredential(config.ApiKey));
        
        _chatDeployment = config.ChatDeployment;
        _embeddingDeployment = config.EmbeddingDeployment;
        _logger = logger;
    }
    
    public async Task<string> GetChatCompletionAsync(
        string prompt,
        CancellationToken cancellationToken = default)
    {
        var chatOptions = new ChatCompletionsOptions
        {
            DeploymentName = _chatDeployment,
            Messages =
            {
                new ChatRequestSystemMessage("Eres un asistente útil."),
                new ChatRequestUserMessage(prompt)
            },
            Temperature = 0.7f,
            MaxTokens = 800,
            NucleusSamplingFactor = 0.9f
        };
        
        try
        {
            var response = await _client.GetChatCompletionsAsync(
                chatOptions,
                cancellationToken);
            
            var choice = response.Value.Choices.FirstOrDefault();
            if (choice == null)
            {
                _logger.LogWarning("No se recibieron respuestas del modelo");
                return string.Empty;
            }
            
            _logger.LogInformation(
                "Chat completion generado. Tokens: {PromptTokens} prompt, {CompletionTokens} completion",
                response.Value.Usage.PromptTokens,
                response.Value.Usage.CompletionTokens);
            
            return choice.Message.Content;
        }
        catch (RequestFailedException ex)
        {
            _logger.LogError(ex, "Error llamando a Azure OpenAI");
            throw;
        }
    }
    
    public async Task<float[]> GetEmbeddingAsync(
        string text,
        CancellationToken cancellationToken = default)
    {
        var embeddingsOptions = new EmbeddingsOptions(
            _embeddingDeployment,
            new List<string> { text });
        
        try
        {
            var response = await _client.GetEmbeddingsAsync(
                embeddingsOptions,
                cancellationToken);
            
            return response.Value.Data[0].Embedding.ToArray();
        }
        catch (RequestFailedException ex)
        {
            _logger.LogError(ex, "Error generando embedding");
            throw;
        }
    }
}

Streaming de Respuestas

public async IAsyncEnumerable<string> GetChatCompletionStreamAsync(
    string prompt,
    [EnumeratorCancellation] CancellationToken cancellationToken = default)
{
    var chatOptions = new ChatCompletionsOptions
    {
        DeploymentName = _chatDeployment,
        Messages =
        {
            new ChatRequestSystemMessage("Eres un asistente útil."),
            new ChatRequestUserMessage(prompt)
        }
    };
    
    var response = await _client.GetChatCompletionsStreamingAsync(
        chatOptions,
        cancellationToken);
    
    await foreach (var update in response.WithCancellation(cancellationToken))
    {
        if (update.ContentUpdate != null)
        {
            yield return update.ContentUpdate;
        }
    }
}

Manejo de Rate Limits

Implementación con Polly

using Polly;
using Polly.RateLimit;

public class RateLimitedAzureOpenAIClient
{
    private readonly AzureOpenAIClient _client;
    private readonly AsyncRateLimitPolicy _rateLimitPolicy;
    
    public RateLimitedAzureOpenAIClient(AzureOpenAIClient client)
    {
        _client = client;
        
        // Limitar a 60 llamadas por minuto
        _rateLimitPolicy = Policy.RateLimitAsync(
            numberOfExecutions: 60,
            perTimeSpan: TimeSpan.FromMinutes(1),
            maxBurst: 10);
    }
    
    public async Task<string> GetChatCompletionAsync(
        string prompt,
        CancellationToken cancellationToken = default)
    {
        return await _rateLimitPolicy.ExecuteAsync(
            async ct => await _client.GetChatCompletionAsync(prompt, ct),
            cancellationToken);
    }
}

Retry con Exponential Backoff

using Polly;
using Polly.Retry;

public class ResilientAzureOpenAIClient
{
    private readonly AzureOpenAIClient _client;
    private readonly AsyncRetryPolicy _retryPolicy;
    private readonly ILogger<ResilientAzureOpenAIClient> _logger;
    
    public ResilientAzureOpenAIClient(
        AzureOpenAIClient client,
        ILogger<ResilientAzureOpenAIClient> logger)
    {
        _client = client;
        _logger = logger;
        
        _retryPolicy = Policy
            .Handle<RequestFailedException>(ex =>
                ex.Status == 429 ||  // Too Many Requests
                ex.Status == 503 ||  // Service Unavailable
                ex.Status == 504)    // Gateway Timeout
            .WaitAndRetryAsync(
                retryCount: 3,
                sleepDurationProvider: attempt => TimeSpan.FromSeconds(Math.Pow(2, attempt)),
                onRetry: (exception, timeSpan, retryCount, context) =>
                {
                    _logger.LogWarning(
                        "Intento {RetryCount} después de {Delay}s debido a: {Error}",
                        retryCount,
                        timeSpan.TotalSeconds,
                        exception.Message);
                });
    }
    
    public async Task<string> GetChatCompletionAsync(
        string prompt,
        CancellationToken cancellationToken = default)
    {
        return await _retryPolicy.ExecuteAsync(
            async ct => await _client.GetChatCompletionAsync(prompt, ct),
            cancellationToken);
    }
}

Monitoreo y Telemetría

Application Insights

using Microsoft.ApplicationInsights;
using Microsoft.ApplicationInsights.DataContracts;

public class MonitoredAzureOpenAIClient
{
    private readonly AzureOpenAIClient _client;
    private readonly TelemetryClient _telemetryClient;
    
    public MonitoredAzureOpenAIClient(
        AzureOpenAIClient client,
        TelemetryClient telemetryClient)
    {
        _client = client;
        _telemetryClient = telemetryClient;
    }
    
    public async Task<string> GetChatCompletionAsync(
        string prompt,
        CancellationToken cancellationToken = default)
    {
        var operation = _telemetryClient.StartOperation<DependencyTelemetry>("AzureOpenAI.ChatCompletion");
        operation.Telemetry.Type = "HTTP";
        operation.Telemetry.Target = "Azure OpenAI";
        
        var stopwatch = Stopwatch.StartNew();
        
        try
        {
            var result = await _client.GetChatCompletionAsync(prompt, cancellationToken);
            
            stopwatch.Stop();
            
            operation.Telemetry.Success = true;
            operation.Telemetry.Duration = stopwatch.Elapsed;
            
            _telemetryClient.TrackMetric("AzureOpenAI.PromptLength", prompt.Length);
            _telemetryClient.TrackMetric("AzureOpenAI.ResponseLength", result.Length);
            _telemetryClient.TrackMetric("AzureOpenAI.LatencyMs", stopwatch.ElapsedMilliseconds);
            
            return result;
        }
        catch (Exception ex)
        {
            stopwatch.Stop();
            
            operation.Telemetry.Success = false;
            operation.Telemetry.Duration = stopwatch.Elapsed;
            
            _telemetryClient.TrackException(ex, new Dictionary<string, string>
            {
                ["PromptLength"] = prompt.Length.ToString(),
                ["Operation"] = "ChatCompletion"
            });
            
            throw;
        }
        finally
        {
            _telemetryClient.StopOperation(operation);
        }
    }
}

Caché de Respuestas

using Microsoft.Extensions.Caching.Memory;
using System.Security.Cryptography;
using System.Text;

public class CachedAzureOpenAIClient
{
    private readonly AzureOpenAIClient _client;
    private readonly IMemoryCache _cache;
    private readonly ILogger<CachedAzureOpenAIClient> _logger;
    private readonly TimeSpan _cacheDuration;
    
    public CachedAzureOpenAIClient(
        AzureOpenAIClient client,
        IMemoryCache cache,
        ILogger<CachedAzureOpenAIClient> logger,
        TimeSpan? cacheDuration = null)
    {
        _client = client;
        _cache = cache;
        _logger = logger;
        _cacheDuration = cacheDuration ?? TimeSpan.FromHours(1);
    }
    
    public async Task<string> GetChatCompletionAsync(
        string prompt,
        bool useCache = true,
        CancellationToken cancellationToken = default)
    {
        if (!useCache)
        {
            return await _client.GetChatCompletionAsync(prompt, cancellationToken);
        }
        
        var cacheKey = GenerateCacheKey(prompt);
        
        if (_cache.TryGetValue<string>(cacheKey, out var cachedResult))
        {
            _logger.LogInformation("Cache HIT para prompt: {PromptHash}", cacheKey);
            return cachedResult;
        }
        
        _logger.LogInformation("Cache MISS para prompt: {PromptHash}", cacheKey);
        
        var result = await _client.GetChatCompletionAsync(prompt, cancellationToken);
        
        _cache.Set(cacheKey, result, _cacheDuration);
        
        return result;
    }
    
    private string GenerateCacheKey(string prompt)
    {
        using var sha256 = SHA256.Create();
        var hashBytes = sha256.ComputeHash(Encoding.UTF8.GetBytes(prompt));
        return $"aoai_{BitConverter.ToString(hashBytes).Replace("-", "").Substring(0, 16).ToLowerInvariant()}";
    }
}

Testing

Unit Tests con Mocks

using Moq;
using Xunit;

public class AzureOpenAIClientTests
{
    [Fact]
    public async Task GetChatCompletionAsync_ReturnsResponse()
    {
        // Arrange
        var mockOptions = new Mock<IOptions<AzureOpenAIOptions>>();
        mockOptions.Setup(o => o.Value).Returns(new AzureOpenAIOptions
        {
            Endpoint = "https://test.openai.azure.com/",
            ApiKey = "test-key",
            ChatDeployment = "gpt-4",
            EmbeddingDeployment = "embedding"
        });
        
        var mockLogger = new Mock<ILogger<AzureOpenAIClient>>();
        
        var client = new AzureOpenAIClient(mockOptions.Object, mockLogger.Object);
        
        // Act & Assert se requiere configuración adicional con cliente real o mock
        // En tests de integración usarías el cliente real
    }
}

Integration Tests

[Collection("AzureOpenAI")]
public class AzureOpenAIIntegrationTests
{
    private readonly AzureOpenAIClient _client;
    
    public AzureOpenAIIntegrationTests()
    {
        var configuration = new ConfigurationBuilder()
            .AddUserSecrets<AzureOpenAIIntegrationTests>()
            .Build();
        
        var options = Options.Create(new AzureOpenAIOptions
        {
            Endpoint = configuration["AzureOpenAI:Endpoint"]!,
            ApiKey = configuration["AzureOpenAI:ApiKey"]!,
            ChatDeployment = configuration["AzureOpenAI:ChatDeployment"]!,
            EmbeddingDeployment = configuration["AzureOpenAI:EmbeddingDeployment"]!
        });
        
        var logger = NullLogger<AzureOpenAIClient>.Instance;
        _client = new AzureOpenAIClient(options, logger);
    }
    
    [Fact]
    public async Task GetChatCompletionAsync_WithSimplePrompt_ReturnsResponse()
    {
        // Arrange
        var prompt = "¿Cuál es la capital de España?";
        
        // Act
        var result = await _client.GetChatCompletionAsync(prompt);
        
        // Assert
        Assert.NotNull(result);
        Assert.NotEmpty(result);
        Assert.Contains("Madrid", result, StringComparison.OrdinalIgnoreCase);
    }
    
    [Fact]
    public async Task GetEmbeddingAsync_WithText_ReturnsVector()
    {
        // Arrange
        var text = "Este es un texto de prueba";
        
        // Act
        var embedding = await _client.GetEmbeddingAsync(text);
        
        // Assert
        Assert.NotNull(embedding);
        Assert.True(embedding.Length > 0);
        Assert.Equal(1536, embedding.Length); // text-embedding-ada-002 dimension
    }
}

Mejores Prácticas

1. Seguridad

// ✅ Usar variables de entorno o Azure Key Vault
var apiKey = Environment.GetEnvironmentVariable("AZURE_OPENAI_KEY");

// ❌ Nunca hardcodear credenciales
// var apiKey = "sk-...";

2. Timeouts Apropiados

var httpClient = new HttpClient
{
    Timeout = TimeSpan.FromSeconds(120) // 2 minutos para operaciones de IA
};

3. Logging Estructurado

_logger.LogInformation(
    "Azure OpenAI request: Model={Model}, PromptTokens={PromptTokens}, CompletionTokens={CompletionTokens}",
    deployment,
    promptTokens,
    completionTokens);

4. Manejo de Costos

public class CostTrackingClient
{
    private long _totalPromptTokens;
    private long _totalCompletionTokens;
    
    public void TrackUsage(int promptTokens, int completionTokens)
    {
        Interlocked.Add(ref _totalPromptTokens, promptTokens);
        Interlocked.Add(ref _totalCompletionTokens, completionTokens);
        
        _logger.LogInformation(
            "Total tokens: {TotalPromptTokens} prompt, {TotalCompletionTokens} completion",
            _totalPromptTokens,
            _totalCompletionTokens);
    }
}

Conclusión

Integrar Azure OpenAI en aplicaciones .NET requiere atención a seguridad, resiliencia y monitoreo. Usa dependency injection, maneja errores apropiadamente, implementa rate limiting y caché cuando sea apropiado. El resultado será una integración robusta y lista para producción.

Palabras clave: Azure OpenAI, .NET integration, GPT-4, secure API, rate limiting, resilience, caching, monitoring

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