metrics improvement

README.md

@@ -22,16 +22,15 @@ The root URL of the API is available here: https://api.helldivers2.dev
 > [!WARNING]
 > The root domain of the API recently changed, it's recommended you use the domain above to avoid problems in the future
 
-We also ask that you send us a `User-Agent` header when making requests (if accessing directly from the browser,
-the headers sent by those should suffice and you don't need to add anything special).
-While this is currently not *required*, we are considering making this required in the future, so adding it now
-is the safer option.
-
-We also ask that you include an `X-Application-Contact` header with either a Discord, email or other contact handle
-so we know how to reach out to you (see below).
-
-We ask this so we can identify the applications making requests, and so we can reach out in case we notice weird or
-incorrect behaviour (or we notice you're generating more traffic than we can handle).
+We ask that you send along a `X-Super-Client` header with the name of your application / domain
+(e.g. `X-Super-Client: api.helldivers2.dev`) and optionally a `X-Super-Contact` with some form of contact if your site
+does not link to any form of contact information we can find. We use this information in case we need to notify our users
+of important changes to the API that may cause disruption of service or when additional restrictions would be imposed
+on your app (to prevent abuse, unintentional or otherwise).
+
+> [!IMPORTANT]
+> While adding `X-Super-Client` and `X-Super-Contact` is currently not required, the `X-Super-Client` header **will**
+> be made obligatory in the future, causing clients who don't send it to fail. For more information see #94
 
 ### Rate limits
 Currently the rate limit is set at 5 requests/10 seconds.

src/Helldivers-2-API/Metrics/ClientMetric.cs

@@ -0,0 +1,74 @@
+using System.Text.RegularExpressions;
+
+namespace Helldivers.API.Metrics;
+
+/// <summary>
+/// Handles the logic for generating the `Client` label in the Prometheus metrics for HTTP requests.
+/// </summary>
+public static partial class ClientMetric
+{
+    /// <summary>
+    /// The name of a client that couldn't be identified.
+    /// </summary>
+    private const string UNKNOWN_CLIENT_NAME = "Unknown";
+
+    /// <summary>
+    /// The name for clients that are developing locally (e.g. localhost, ...).
+    /// </summary>
+    private const string LOCAL_DEVELOPMENT_CLIENT_NAME = "Development";
+
+    [GeneratedRegex(@"^[a-z0-9]{24}--.+\.netlify\.app$")]
+    private static partial Regex IsNetlifyApp();
+
+    /// <summary>
+    /// Extracts the name of the client for the incoming request.
+    /// </summary>
+    public static string GetClientName(HttpContext context)
+    {
+        // If we have an authenticated user, use their name instead
+        if (context.User.Identity is { Name: { } name })
+            return name;
+
+        // If the client sends `X-Super-Client` we use that name
+        if (context.Request.Headers.TryGetValue("X-Super-Client", out var superClient))
+            if (string.IsNullOrWhiteSpace(superClient) is false)
+                return superClient!;
+
+        if (GetBrowserClientName(context.Request) is { } clientName)
+            return clientName;
+
+        return UNKNOWN_CLIENT_NAME;
+    }
+
+    /// <summary>
+    /// If the client is a browser it sends specific headers along.
+    /// Attempt to parse out those headers to get the domain and perform some additional normalization.
+    ///
+    /// If we can't find any of those headers simply return <c>null</c>
+    /// </summary>
+    private static string? GetBrowserClientName(HttpRequest request)
+    {
+        string? result = null;
+        if (string.IsNullOrWhiteSpace(request.Headers.Referer) is false)
+            result = request.Headers.Referer!;
+        if (string.IsNullOrWhiteSpace(request.Headers.Origin) is false)
+            result = request.Headers.Origin!;
+
+        if (result is not null && Uri.TryCreate(result, UriKind.Absolute, out var uri))
+        {
+            // Localhost etc just return local development for a client name.
+            if (uri.Host.Equals("localhost", StringComparison.InvariantCultureIgnoreCase))
+                return LOCAL_DEVELOPMENT_CLIENT_NAME;
+
+            // Netlify seems to generate urls with random prefixes like following:
+            // <24 characters random>--<projectname>.netlify.app
+            // we normalize to <projectname>.netlify.app
+            if (IsNetlifyApp().IsMatch(uri.Host))
+                return uri.Host[26..];
+
+            return uri.Host;
+        }
+
+        return result;
+    }
+}

src/Helldivers-2-API/Middlewares/RedirectFlyDomainMiddleware.cs

@@ -0,0 +1,22 @@
+namespace Helldivers.API.Middlewares;
+
+/// <summary>
+/// Automatically generates a redirect if a user still uses the deprecated `fly.io` URL.
+/// </summary>
+public class RedirectFlyDomainMiddleware : IMiddleware
+{
+    private const string RedirectDomain = "https://api.helldivers2.dev";
+
+    /// <inheritdoc />
+    public async Task InvokeAsync(HttpContext context, RequestDelegate next)
+    {
+        if (context.Request.Host.Host.Equals("helldivers-2-dotnet.fly.dev", StringComparison.InvariantCultureIgnoreCase))
+        {
+            var url = $"{RedirectDomain}{context.Request.Path}";
+
+            context.Response.Redirect(url, permanent: true);
+        }
+
+        await next(context);
+    }
+}

src/Helldivers-2-API/Program.cs

@@ -1,6 +1,7 @@
 using Helldivers.API.Configuration;
 using Helldivers.API.Controllers;
 using Helldivers.API.Controllers.V1;
+using Helldivers.API.Metrics;
 using Helldivers.API.Middlewares;
 using Helldivers.Core.Extensions;
 using Helldivers.Models;
@@ -42,6 +43,7 @@
 
 // Register the rate limiting middleware.
 builder.Services.AddTransient<RateLimitMiddleware>();
+builder.Services.AddTransient<RedirectFlyDomainMiddleware>();
 
 // Register the memory cache, used in the rate limiting middleware.
 builder.Services.AddMemoryCache();
@@ -181,23 +183,12 @@
 
 var app = builder.Build();
 
+app.UseMiddleware<RedirectFlyDomainMiddleware>();
+
 // Track telemetry for Prometheus (Fly.io metrics)
 app.UseHttpMetrics(options =>
 {
-    options.AddCustomLabel("Client", context =>
-    {
-        if (context.User.Identity is { Name: { } name })
-            return name;
-
-        // TODO: document custom header that clients can send to identify themselves.
-
-        if (string.IsNullOrWhiteSpace(context.Request.Headers.Referer) is false)
-            return context.Request.Headers.Referer!;
-        if (string.IsNullOrWhiteSpace(context.Request.Headers.Origin) is false)
-            return context.Request.Headers.Origin!;
-
-        return "Unknown";
-    });
+    options.AddCustomLabel("Client", ClientMetric.GetClientName);
 });
 
 // Use response compression for smaller payload sizes

src/Helldivers-2-Sync/Hosted/ArrowHeadSyncService.cs

@@ -22,8 +22,8 @@ public sealed partial class ArrowHeadSyncService(
     StorageFacade storage
 ) : BackgroundService
 {
-    private static readonly Histogram SteamSyncMetric =
-        Metrics.CreateHistogram("helldivers_sync_steam", "All Steam synchronizations");
+    private static readonly Histogram ArrowHeadSyncMetric =
+        Metrics.CreateHistogram("helldivers_sync_arrowhead", "All ArrowHead synchronizations");
 
     #region Source generated logging
 
@@ -49,7 +49,7 @@ protected override async Task ExecuteAsync(CancellationToken cancellationToken)
         {
             try
             {
-                using var _ = SteamSyncMetric.NewTimer();
+                using var _ = ArrowHeadSyncMetric.NewTimer();
                 await using var scope = scopeFactory.CreateAsyncScope();
 
                 await SynchronizeAsync(scope.ServiceProvider, cancellationToken);

src/Helldivers-2-Sync/Hosted/SteamSyncService.cs

@@ -16,8 +16,8 @@ public sealed partial class SteamSyncService(
     IServiceScopeFactory scopeFactory
 ) : BackgroundService
 {
-    private static readonly Histogram ArrowHeadSyncMetric =
-        Metrics.CreateHistogram("helldivers_sync_arrowhead", "All ArrowHead synchronizations");
+    private static readonly Histogram SteamSyncMetric =
+        Metrics.CreateHistogram("helldivers_sync_steam", "All Steam synchronizations");
 
     #region Source generated logging
 
@@ -35,7 +35,7 @@ protected override async Task ExecuteAsync(CancellationToken cancellationToken)
         {
             try
             {
-                using var _ = ArrowHeadSyncMetric.NewTimer();
+                using var _ = SteamSyncMetric.NewTimer();
                 await using var scope = scopeFactory.CreateAsyncScope();
 
                 var feed = await scope

src/Helldivers-2-Sync/Services/ArrowHeadApiService.cs

@@ -3,7 +3,6 @@
 using Helldivers.Sync.Configuration;
 using Microsoft.Extensions.Options;
 using System.Net.Http.Headers;
-using System.Runtime.CompilerServices;
 using System.Text.Json;
 
 namespace Helldivers.Sync.Services;