Add :peer_applications

Author: probably-not

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## [0.2.1] - 2026-01-27
+
+### Added
+
+- `:peer_applications` - For custom pools, you can decide which applications will be started on the peer nodes. In the default pool this defaults to only `:safe_nif`, and if not passed in to custom pools it will default to `:safe_nif` as well
+
 ## [0.2.0] - 2026-01-27
 
 Pooling `:peer` nodes has been implemented!

lib/safe_nif.ex

@@ -31,8 +31,11 @@ defmodule SafeNIF do
     * `:name` (**required**) - An `t:atom/0` name to give to the pool.
     * `:size` - How many workers to put in the pool. Defaults to `System.schedulers_online/0`.
     * `:idle_timeout` - How long to allow the pool and nodes to be idle until we start scaling them down.
+    * `:peer_applications` - A list of applications to start on the peer node, defaulting to just `:safe_nif`.
+      If you need a custom list of applications that must start on the peer node, make sure to pass their names into the pool.
   """
-  @type pool_start_opt() :: {:name, atom()} | {:size, pos_integer()} | {:idle_timeout, timeout()}
+  @type pool_start_opt() ::
+          {:name, atom()} | {:size, pos_integer()} | {:idle_timeout, timeout()} | {:peer_applications, [atom()]}
 
   @doc false
   defdelegate child_spec(args), to: SafeNIF.Pool
@@ -77,6 +80,8 @@ defmodule SafeNIF do
     * `:name` (**required**) - An `t:atom/0` name to give to the pool.
     * `:size` - How many workers to put in the pool. Defaults to `System.schedulers_online/0`.
     * `:idle_timeout` - How long to allow the pool and nodes to be idle until we start scaling them down.
+    * `:peer_applications` - A list of applications to start on the peer node, defaulting to just `:safe_nif`.
+      If you need a custom list of applications that must start on the peer node, make sure to pass their names into the pool.
 
   """
   @spec wrap(runnable(), [wrap_opt()]) :: {:ok, term()} | {:error, term()}

lib/safe_nif/application.ex

@@ -5,7 +5,7 @@ defmodule SafeNIF.Application do
 
   @impl true
   def start(_type, _args) do
-    children = [{SafeNIF, name: SafeNIF.Pool.default_pool_name()}]
+    children = [{SafeNIF, name: SafeNIF.Pool.default_pool_name(), peer_applications: [:safe_nif]}]
     opts = [strategy: :one_for_one, name: SafeNIF.Supervisor]
     Supervisor.start_link(children, opts)
   end

lib/safe_nif/pool.ex

@@ -10,7 +10,8 @@ defmodule SafeNIF.Pool do
 
   defmodule State do
     @moduledoc false
-    defstruct [:activity_info, :pool_max_idle_time]
+    @enforce_keys [:activity_info, :pool_max_idle_time, :peer_applications]
+    defstruct [:activity_info, :pool_max_idle_time, :peer_applications]
   end
 
   def default_pool_name do
@@ -69,14 +70,22 @@ defmodule SafeNIF.Pool do
   @impl NimblePool
   def init_pool(opts) do
     idle_timeout = Keyword.get(opts, :idle_timeout, @default_idle_timeout)
-    pool_state = %__MODULE__.State{activity_info: init_activity_info(), pool_max_idle_time: idle_timeout}
+    peer_applications = Keyword.get(opts, :peer_applications, [:safe_nif])
+
+    pool_state = %__MODULE__.State{
+      activity_info: init_activity_info(),
+      pool_max_idle_time: idle_timeout,
+      peer_applications: peer_applications
+    }
+
     {:ok, pool_state}
   end
 
   @impl NimblePool
   def init_worker(%__MODULE__.State{} = pool_state) do
     pool_pid = self()
-    async = fn -> start_peer(pool_pid) end
+    peer_applications = pool_state.peer_applications
+    async = fn -> start_peer(pool_pid, peer_applications) end
     {:async, async, pool_state}
   end
 
@@ -212,7 +221,7 @@ defmodule SafeNIF.Pool do
     Node.spawn_monitor(peer, WrappedCall.call(caller, runnable))
   end
 
-  defp start_peer(pool_pid) do
+  defp start_peer(pool_pid, peer_applications) do
     node_name = :peer.random_name()
     caller = self()
 
@@ -232,7 +241,7 @@ defmodule SafeNIF.Pool do
 
     add_code_paths(peer)
     transfer_configuration(peer)
-    ensure_apps_started(peer)
+    ensure_apps_started(peer, peer_applications)
     send(pool_pid, {:link_controller, peer})
     %__MODULE__{node: peer, controller_pid: controller_pid, last_checkin: System.monotonic_time()}
   end
@@ -255,10 +264,8 @@ defmodule SafeNIF.Pool do
     end)
   end
 
-  defp ensure_apps_started(node) do
-    started_names = Enum.map(Application.started_applications(), fn {name, _, _} -> name end)
-
-    Enum.reduce(started_names, MapSet.new(), fn app, started ->
+  defp ensure_apps_started(node, peer_applications) do
+    Enum.reduce(peer_applications, MapSet.new(), fn app, started ->
       maybe_start_app(node, app, started)
     end)
   end

mix.exs

@@ -1,7 +1,7 @@
 defmodule SafeNIF.MixProject do
   use Mix.Project
 
-  @version "0.2.0"
+  @version "0.2.1"
   @source_url "https://github.com/probably-not/safe-nif"
   @homepage_url @source_url