ocelot-gateway-guide

Guide Ocelot API Gateway

Workflow — mise en place pas à pas

1. Installer les packages

dotnet add package Ocelot                          # Core — toujours requis
dotnet add package Ocelot.Provider.Consul          # Service Discovery Consul
dotnet add package Ocelot.Provider.Eureka          # Service Discovery Eureka
dotnet add package Ocelot.Cache.CacheManager       # Cache distribué
dotnet add package Ocelot.Tracing.OpenTracing      # Tracing distribué

2. Brancher Ocelot dans Program.cs

// Program.cs (.NET 8+)
var builder = WebApplication.CreateBuilder(args);

// Charge ocelot.json en priorité sur appsettings.json
builder.Configuration
    .AddJsonFile("ocelot.json", optional: false, reloadOnChange: true)
    .AddJsonFile($"ocelot.{builder.Environment.EnvironmentName}.json",
                 optional: true, reloadOnChange: true);

builder.Services
    .AddOcelot(builder.Configuration)
    .AddCacheManager(x => x.WithDictionaryHandle())  // cache en mémoire
    .AddConsul()                                      // si Consul utilisé
    ;

builder.Services.AddAuthentication()
    .AddJwtBearer("Bearer", options =>
    {
        options.Authority = builder.Configuration["Jwt:Authority"];
        options.Audience  = builder.Configuration["Jwt:Audience"];
    });

var app = builder.Build();
await app.UseOcelot();
app.Run();

3. Définir les routes dans ocelot.json

Chaque route = un objet dans "Routes". Minima obligatoires :

{
  "Routes": [
    {
      "DownstreamPathTemplate": "/api/payments/{everything}",
      "DownstreamScheme": "https",
      "DownstreamHostAndPorts": [
        { "Host": "payment-service", "Port": 8080 }
      ],
      "UpstreamPathTemplate": "/payments/{everything}",
      "UpstreamHttpMethod": ["GET", "POST", "PUT", "DELETE"],

      "AuthenticationOptions": {
        "AuthenticationProviderKey": "Bearer"
      },

      "RateLimitOptions": {
        "EnableRateLimiting": true,
        "Period": "1m",
        "PeriodTimespan": 60,
        "Limit": 100
      },

      "QoSOptions": {
        "ExceptionsAllowedBeforeBreaking": 3,
        "DurationOfBreak": 10000,
        "TimeoutValue": 5000
      },

      "FileCacheOptions": {
        "TtlSeconds": 30,
        "Region": "payments"
      }
    },
    {
      "DownstreamPathTemplate": "/api/orders/{everything}",
      "DownstreamScheme": "https",
      "DownstreamHostAndPorts": [
        { "Host": "order-svc-1", "Port": 8080 },
        { "Host": "order-svc-2", "Port": 8080 }
      ],
      "UpstreamPathTemplate": "/orders/{everything}",
      "UpstreamHttpMethod": ["GET", "POST"],
      "LoadBalancerOptions": { "Type": "RoundRobin" }
    }
  ],
  "GlobalConfiguration": {
    "BaseUrl": "https://api.company.com",
    "RateLimitOptions": {
      "DisableRateLimitHeaders": false,
      "QuotaExceededMessage": "Trop de requêtes, réessayez plus tard",
      "HttpStatusCode": 429
    }
  }
}