feat(server): add observability and operator controls (#16)

tests/FinalFactory.Rendezvous.Tests/Server/Abuse/AbuseProtectionTests.cs

@@ -6,6 +6,7 @@ using FinalFactory.Rendezvous.Server.Http;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.HttpOverrides;
+using Microsoft.AspNetCore.Routing;
 using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Extensions.Options;
 
@@ -86,6 +87,9 @@ public sealed class AbuseProtectionTests
         AbuseProtectionService protection = new(Options.Create(options));
         IPAddress source = IPAddress.Parse("198.51.100.10");
 
+        Assert.True(protection.IsOperatorSourceAllowed(source));
+        Assert.True(protection.IsOperatorSourceAllowed(IPAddress.Parse("::ffff:198.51.100.10")));
+        Assert.False(protection.IsOperatorSourceAllowed(IPAddress.Parse("198.51.100.11")));
         AssertAccepted(protection, source, "BrowseSessions");
         AssertAccepted(protection, source, "BrowseSessions");
         AssertRejected(protection, source, "BrowseSessions");
@@ -93,6 +97,57 @@ public sealed class AbuseProtectionTests
         AssertRejected(protection, source, "RenewSessionLease");
     }
 
+    [Fact]
+    public void PublicSaturationCannotConsumeTheOperatorPartition()
+    {
+        AbuseProtectionOptions options = PermissiveOptions();
+        options.HttpGlobalRequestsPerWindow = 1;
+        options.HttpOptionalRequestsPerWindow = 1;
+        options.OperatorGlobalRequestsPerWindow = 1;
+        AbuseProtectionService protection = new(Options.Create(options));
+        IPAddress source = IPAddress.Parse("198.51.100.10");
+
+        AssertAccepted(protection, source, "BrowseSessions");
+        AssertRejected(protection, source, "BrowseSessions");
+        Assert.True(protection.TryAcquireOperatorIngress(source, out var lease, out _));
+        lease!.Dispose();
+        Assert.False(protection.TryAcquireOperatorIngress(source, out _, out _));
+    }
+
+    [Fact]
+    public async Task DeniedOperatorSourcesConsumeTheBoundedPublicPartition()
+    {
+        AbuseProtectionOptions options = PermissiveOptions();
+        options.OperatorAllowedAddresses = ["192.0.2.10"];
+        options.HttpGlobalRequestsPerWindow = 1;
+        options.HttpOptionalRequestsPerWindow = 1;
+        options.HttpIpPrefixRequestsPerWindow = 1;
+        options.HttpOptionalIpPrefixRequestsPerWindow = 1;
+        AbuseProtectionService protection = new(Options.Create(options));
+        bool dispatched = false;
+        HttpAbuseProtectionMiddleware middleware = new(
+            _ =>
+            {
+                dispatched = true;
+                return Task.CompletedTask;
+            },
+            protection);
+
+        DefaultHttpContext first = Context("198.51.100.10");
+        first.SetEndpoint(new Endpoint(
+            _ => Task.CompletedTask,
+            new EndpointMetadataCollection(new EndpointNameMetadata("GetOperatorStatus")),
+            "operator-status"));
+        await middleware.InvokeAsync(first);
+        Assert.Equal(StatusCodes.Status404NotFound, first.Response.StatusCode);
+
+        DefaultHttpContext repeated = Context("198.51.100.10");
+        repeated.SetEndpoint(first.GetEndpoint());
+        await middleware.InvokeAsync(repeated);
+        Assert.Equal(StatusCodes.Status429TooManyRequests, repeated.Response.StatusCode);
+        Assert.False(dispatched);
+    }
+
     [Fact]
     public void ResourceBudgetsRemainIsolatedAcrossTenantAndPrincipalScopes()
     {
@@ -354,7 +409,8 @@ public sealed class AbuseProtectionTests
     {
         const string canary = "credential-canary <script> endpoint=203.0.113.8:9000";
         DefaultHttpContext context = Context("198.51.100.10");
-        RendezvousExceptionHandler handler = new();
+        RendezvousExceptionHandler handler = new(
+            NullLogger<RendezvousExceptionHandler>.Instance);
 
         Assert.True(await handler.TryHandleAsync(
             context,
@@ -438,6 +494,11 @@ public sealed class AbuseProtectionTests
         HealthGlobalConcurrency = 10_000,
         HealthIpPrefixRequestsPerWindow = 10_000,
         HealthIpPrefixConcurrency = 1_000,
+        OperatorAllowedAddresses = ["198.51.100.10"],
+        OperatorGlobalRequestsPerWindow = 10_000,
+        OperatorGlobalConcurrency = 10_000,
+        OperatorIpPrefixRequestsPerWindow = 10_000,
+        OperatorIpPrefixConcurrency = 1_000,
         HttpGlobalRequestsPerWindow = 10_000,
         HttpOptionalRequestsPerWindow = 9_000,
         HttpIpPrefixRequestsPerWindow = 10_000,