Allow passing an :env option to set the environment on the Port transport

lib/playwright_ex/processes/port_transport.ex

@@ -31,7 +31,7 @@ defmodule PlaywrightEx.PortTransport do
   Start the PortTransport and link it to the connection process.
   """
   def start_link(opts) do
-    opts = Keyword.validate!(opts, [:executable, :name, :connection_name])
+    opts = Keyword.validate!(opts, [:executable, :name, :connection_name, :env])
     name = Keyword.get(opts, :name, @default_name)
     GenServer.start_link(__MODULE__, Map.new(opts), name: name)
   end
@@ -42,12 +42,19 @@ defmodule PlaywrightEx.PortTransport do
   end
 
   @impl GenServer
-  def init(%{executable: executable} = opts) do
+  def init(%{executable: executable, env: env} = opts) when map_size(env) == 0 do
     port = Port.open({:spawn_executable, executable}, [:binary, :stderr_to_stdout, args: ["run-driver"]])
     connection_name = Map.get(opts, :connection_name, Connection)
     {:ok, %__MODULE__{port: port, connection_name: connection_name}}
   end
 
+  def init(%{executable: executable, env: env} = opts) when map_size(env) > 0 do
+    env = Enum.map(env, fn {k, v} -> {maybe_charlist(k), maybe_charlist(v)} end)
+    port = Port.open({:spawn_executable, executable}, [:binary, :stderr_to_stdout, {:args, ["run-driver"]}, {:env, env}])
+    connection_name = Map.get(opts, :connection_name, Connection)
+    {:ok, %__MODULE__{port: port, connection_name: connection_name}}
+  end
+
   @impl GenServer
   def handle_cast({:post, msg}, state) do
     frame = to_json(msg)
@@ -105,4 +112,7 @@ defmodule PlaywrightEx.PortTransport do
     |> Serialization.deep_key_underscore()
     |> Map.update(:method, nil, &Serialization.underscore/1)
   end
+
+  defp maybe_charlist(value) when is_list(value), do: value
+  defp maybe_charlist(value) when is_binary(value), do: String.to_charlist(value)
 end

lib/playwright_ex/supervisor.ex

@@ -11,6 +11,7 @@ defmodule PlaywrightEx.Supervisor do
     If provided, uses WebSocket transport. Otherwise uses local Port.
     If no browser param is provided, `chromium` is used by default.
   - `:executable` - Path to playwright CLI (only for Port transport)
+  - `:env` - A `%{String.t() => String.t()}` map of environment variables to set for the browser instance (only for Port transport).
   - `:timeout` - Connection timeout
   - `:js_logger` - Module for logging JS console messages
   - `:name` - Optional name for this supervisor instance. Defaults to `PlaywrightEx.Supervisor`.
@@ -43,7 +44,8 @@ defmodule PlaywrightEx.Supervisor do
         :fail_on_unknown_opts,
         executable: "playwright",
         js_logger: nil,
-        name: __MODULE__
+        name: __MODULE__,
+        env: %{}
       ])
 
     Supervisor.start_link(__MODULE__, Map.new(opts), name: opts[:name])
@@ -100,12 +102,12 @@ defmodule PlaywrightEx.Supervisor do
     {child_spec, {WebSocketTransport, transport_name}}
   end
 
-  defp transport_child_spec(%{executable: executable, name: name}, connection_name) do
+  defp transport_child_spec(%{executable: executable, name: name, env: env}, connection_name) do
     executable = validate_executable!(executable)
 
     transport_name = Module.concat(name, "PortTransport")
 
-    child_spec = {PortTransport, executable: executable, name: transport_name, connection_name: connection_name}
+    child_spec = {PortTransport, executable: executable, name: transport_name, connection_name: connection_name, env: env}
     {child_spec, {PortTransport, transport_name}}
   end