Add first-class listener connection caps

test/parrhesia/config_test.exs

@@ -1,6 +1,8 @@
 defmodule Parrhesia.ConfigTest do
   use ExUnit.Case, async: true
 
+  alias Parrhesia.Web.Listener
+
   test "returns configured relay limits/policies/features" do
     assert Parrhesia.Config.get([:limits, :max_frame_bytes]) == 1_048_576
     assert Parrhesia.Config.get([:limits, :max_event_bytes]) == 262_144
@@ -22,6 +24,11 @@ defmodule Parrhesia.ConfigTest do
     assert Parrhesia.Config.get([:features, :verify_event_signatures]) == false
     assert Parrhesia.Config.get([:features, :nip_50_search]) == true
     assert Parrhesia.Config.get([:features, :marmot_push_notifications]) == false
+
+    assert Application.get_env(:parrhesia, :listeners, %{})
+           |> Keyword.get(:public)
+           |> then(&Listener.from_opts(listener: &1))
+           |> Map.get(:max_connections) == 20_000
   end
 
   test "returns default for unknown keys" do

test/parrhesia/web/listener_test.exs

@@ -0,0 +1,71 @@
+defmodule Parrhesia.Web.ListenerTest do
+  use ExUnit.Case, async: true
+
+  alias Parrhesia.Web.Listener
+
+  test "listener max_connections is translated to ThousandIsland num_connections" do
+    options =
+      listener(%{max_connections: 20_000})
+      |> Listener.bandit_options()
+
+    assert Keyword.get(options, :thousand_island_options) == [num_connections: 200]
+  end
+
+  test "listener max_connections honors custom num_acceptors when deriving the limit" do
+    options =
+      listener(%{
+        max_connections: 20_000,
+        bandit_options: [thousand_island_options: [num_acceptors: 80]]
+      })
+      |> Listener.bandit_options()
+
+    thousand_island_options = Keyword.get(options, :thousand_island_options)
+
+    assert Keyword.get(thousand_island_options, :num_acceptors) == 80
+    assert Keyword.get(thousand_island_options, :num_connections) == 250
+  end
+
+  test "explicit ThousandIsland num_connections overrides the first-class listener cap" do
+    options =
+      listener(%{
+        max_connections: 20_000,
+        bandit_options: [thousand_island_options: [num_acceptors: 80, num_connections: 50]]
+      })
+      |> Listener.bandit_options()
+
+    thousand_island_options = Keyword.get(options, :thousand_island_options)
+
+    assert Keyword.get(thousand_island_options, :num_acceptors) == 80
+    assert Keyword.get(thousand_island_options, :num_connections) == 50
+  end
+
+  test "metrics listeners default to a lower max_connections ceiling" do
+    listener = Listener.from_opts(listener: %{id: :metrics, bind: %{port: 9568}})
+
+    assert listener.max_connections == 1_024
+  end
+
+  defp listener(overrides) do
+    Listener.from_opts(
+      listener:
+        Map.merge(
+          %{
+            id: :public,
+            enabled: true,
+            bind: %{ip: {127, 0, 0, 1}, port: 4413},
+            transport: %{scheme: :http, tls: %{mode: :disabled}},
+            proxy: %{trusted_cidrs: [], honor_x_forwarded_for: true},
+            network: %{allow_all: true},
+            features: %{
+              nostr: %{enabled: true},
+              admin: %{enabled: true},
+              metrics: %{enabled: true, access: %{private_networks_only: true}, auth_token: nil}
+            },
+            auth: %{nip42_required: false, nip98_required_for_admin: true},
+            baseline_acl: %{read: [], write: []}
+          },
+          overrides
+        )
+    )
+  end
+end