feat: cookie name as cluster name

README.md

@@ -37,11 +37,13 @@ config :libcluster,
           database: "postgres",
           port: 5432,
           parameters: [],
+          # optional, defaults to node cookie
           channel_name: "cluster"
       ],
     ]
   ]
 ```
+
 Then add it to your supervision tree:
 
 ```elixir
@@ -60,6 +62,6 @@ defmodule MyApp do
 end
 ```
 
-
 ## Acknowledgements
-A special thank you to [@gotbones](https://twitter.com/gotbones) for creating libcluster and [@kevinbuch_](https://twitter.com/kevinbuch_) for the original inspiration for this strategy.
+
+A special thank you to [@gotbones](https://twitter.com/gotbones) for creating libcluster and [@kevinbuch\_](https://twitter.com/kevinbuch_) for the original inspiration for this strategy.

lib/strategy.ex

@@ -11,7 +11,7 @@ defmodule LibclusterPostgres.Strategy do
   ## Options
 
   * `heartbeat_interval` - The interval at which to send heartbeat messages in milliseconds (optional; default: 5_000)
-  * `channel_name` - The name of the channel to which nodes will listen and notify (optional; default: "cluster")
+  * `channel_name` - The name of the channel to which nodes will listen and notify (optional; defaults to the result of `Node.get_cookie/0`)
   """
   use GenServer
 
@@ -24,18 +24,21 @@ defmodule LibclusterPostgres.Strategy do
           {:ok, %{:config => list(), :meta => map(), optional(any()) => any()},
            {:continue, :connect}}
   def init([state]) do
+    channel_name = Keyword.get(state.config, :channel_name, clean_cookie(Node.get_cookie()))
+
     opts = [
       hostname: Keyword.fetch!(state.config, :hostname),
       username: Keyword.fetch!(state.config, :username),
       password: Keyword.fetch!(state.config, :password),
       database: Keyword.fetch!(state.config, :database),
       port: Keyword.fetch!(state.config, :port),
       parameters: Keyword.fetch!(state.config, :parameters),
-      channel_name: Keyword.fetch!(state.config, :channel_name)
+      channel_name: channel_name
     ]
 
     config =
       state.config
+      |> Keyword.put_new(:channel_name, channel_name)
       |> Keyword.put_new(:heartbeat_interval, 5_000)
       |> Keyword.delete(:url)
 
@@ -103,4 +106,11 @@ defmodule LibclusterPostgres.Strategy do
   defp heartbeat(interval) when interval >= 0 do
     Process.send_after(self(), :heartbeat, interval)
   end
+
+  # Replaces all non alphanumeric values into underescore
+  defp clean_cookie(cookie) when is_atom(cookie), do: cookie |> Atom.to_string() |> clean_cookie()
+
+  defp clean_cookie(str) when is_binary(str) do
+    String.replace(str, ~r/\W/, "_")
+  end
 end

mix.exs

@@ -11,6 +11,7 @@ defmodule LibclusterPostgres.MixProject do
       deps: deps(),
       package: package(),
       docs: docs(),
+      aliases: aliases(),
       source_url: "https://github.com/supabase/libcluster_postgres",
       elixirc_paths: elixirc_paths(Mix.env()),
       description: "Postgres strategy for libcluster"
@@ -49,4 +50,10 @@ defmodule LibclusterPostgres.MixProject do
 
   defp elixirc_paths(:test), do: ["lib", "test", "test/support"]
   defp elixirc_paths(_), do: ["lib"]
+
+  defp aliases() do
+    [
+      test: ["cmd epmd -daemon", "test"]
+    ]
+  end
 end

test/strategy_test.exs

@@ -1,5 +1,5 @@
 defmodule LibclusterPostgres.StrategyTest do
-  use ExUnit.Case
+  use ExUnit.Case, async: false
 
   alias Postgrex.Notifications
 
@@ -25,4 +25,30 @@ defmodule LibclusterPostgres.StrategyTest do
 
     assert_receive {:notification, _, _, ^channel_name, ^node}, 1000
   end
+
+  describe "connect via cookie" do
+    @cookie_config Keyword.put(@config, :channel_name, "my_random__123_long_cookie")
+    @cookie :"my-random-#123-long-cookie"
+    setup do
+      cookie = Node.get_cookie()
+      Node.set_cookie(Node.self(), @cookie)
+
+      on_exit(fn ->
+        Node.set_cookie(Node.self(), cookie)
+      end)
+    end
+
+    test "cookie default connection" do
+      verify_conn_notification = start_supervised!({Notifications, @cookie_config})
+      Notifications.listen(verify_conn_notification, @cookie_config[:channel_name])
+
+      config = Keyword.delete(@cookie_config, :channel_name)
+      topologies = [postgres: [strategy: LibclusterPostgres.Strategy, config: config]]
+      start_supervised!({Cluster.Supervisor, [topologies]})
+
+      channel_name = @cookie_config[:channel_name]
+      node = "#{node()}"
+      assert_receive {:notification, _, _, ^channel_name, ^node}, 1000
+    end
+  end
 end

test/test_helper.exs

@@ -1 +1,4 @@
+# start distributed node
+:net_kernel.start([:"[email protected]"])
+
 ExUnit.start()