chore: add workflows + license

src/AltGen.API/.dockerignore

@@ -0,0 +1,2 @@
+appsettings*.json
+Dockerfile

src/AltGen.API/Dockerfile

@@ -0,0 +1,17 @@
+# setup stage
+FROM mcr.microsoft.com/dotnet/sdk:9.0 AS setup-stage
+WORKDIR /app
+COPY *.csproj ./
+RUN dotnet restore
+COPY . .
+
+# build stage
+FROM setup-stage AS build-stage
+RUN dotnet publish -c Release -o dist
+
+# production stage
+FROM mcr.microsoft.com/dotnet/aspnet:9.0 AS production-stage
+WORKDIR /app
+COPY --from=build-stage /app/dist ./
+EXPOSE 8080
+ENTRYPOINT ["dotnet", "AltGen.API.dll"]

src/AltGen.API/Generate/Providers/Gemini/GeminiService.cs

@@ -4,7 +4,8 @@ class GeminiService(HttpClient httpClient) : IGeminiService
 {
   const string BaseUri = "https://generativelanguage.googleapis.com/v1beta/models";
   const string Method = "generateContent";
-  const string ModelId = "gemini-1.5-flash";
+  // TODO: Maybe this is configurable by the user via request
+  const string ModelId = "gemini-2.0-flash";
   const string ApiKeyQueryKey = "key";
 
   // TODO: Use Lazy<T> to load the prompt resource
@@ -52,6 +53,8 @@ class GeminiService(HttpClient httpClient) : IGeminiService
     var response = await _httpClient.PostAsJsonAsync(requestUri, request, Options);
     var content = await response.Content.ReadAsStringAsync();
 
+    // TODO: Propogate the error response from gemini in the exception
+    // we throw here. Need to figure out how gemini returns errors
     if (response.IsSuccessStatusCode is false)
     {
       throw new AltGenException("Failed to generate alt text.");

src/AltGen.API/Program.cs

@@ -1,3 +1,6 @@
+using System.Globalization;
+using System.Threading.RateLimiting;
+
 var builder = WebApplication.CreateBuilder(args);
 
 builder.Services.AddProblemDetails();
@@ -7,6 +10,41 @@ builder.Services.AddHttpClient<IGeminiService, GeminiService>();
 builder.Services.AddSingleton<IAltTextProviderFactory, AltTextProviderFactory>();
 builder.Services.AddKeyedSingleton<IAltTextProvider, GeminiAltTextProvider>(LLMProvider.Gemini);
 
+builder.Services.AddRateLimiter(
+  static o =>
+  {
+    o.RejectionStatusCode = StatusCodes.Status429TooManyRequests;
+
+    o.OnRejected = static (context, rateLimitInfo) =>
+    {
+      if (context.Lease.TryGetMetadata(MetadataName.RetryAfter, out var retryAfter))
+      {
+        var retryDate = DateTime.UtcNow.Add(retryAfter);
+        context.HttpContext.Response.Headers.Append(
+          "x-retry-after",
+          retryDate.ToString("o", CultureInfo.InvariantCulture)
+        );
+      }
+
+      return ValueTask.CompletedTask;
+    };
+
+    o.GlobalLimiter = PartitionedRateLimiter.Create<HttpContext, string>(
+      static ctx => RateLimitPartition.GetFixedWindowLimiter(
+        partitionKey: ctx.Request.Headers["X-Forwarded-For"].ToString()
+          ?? ctx.Connection.RemoteIpAddress?.ToString()
+          ?? "unknown",
+        factory: static partition => new FixedWindowRateLimiterOptions()
+        {
+          PermitLimit = 10,
+          QueueLimit = 0,
+          Window = TimeSpan.FromHours(1)
+        }
+      )
+    );
+  }
+);
+
 var app = builder.Build();
 
 if (app.Environment.IsDevelopment())
@@ -14,6 +52,11 @@ if (app.Environment.IsDevelopment())
   app.MapOpenApi();
 }
 
+if (app.Environment.IsProduction())
+{
+  app.UseRateLimiter();
+}
+
 app.UseHttpsRedirection();
 
 app.UseStatusCodePages();