Make root path configurable from outside (#217)

README.md

@@ -52,6 +52,8 @@ The following environment variables configure Livebook:
 
   * LIVEBOOK_SECRET_KEY_BASE - sets a secret key that is used to sign and encrypt the session and other payloads used by Livebook. Must be at least 64 characters long and it can be generated by commands such as: `openssl rand -base64 48`. Defaults to a random secret on every boot.
 
+  * LIVEBOOK_ROOT_PATH - the root path to use for file selection.
+
 <!-- Environment variables -->
 ## License
 

config/runtime.exs

@@ -6,6 +6,8 @@ config :livebook, LivebookWeb.Endpoint,
     Livebook.Config.secret!("LIVEBOOK_SECRET_KEY_BASE") ||
       Base.encode64(:crypto.strong_rand_bytes(48))
 
+config :livebook, :root_path, Livebook.Config.root_path!("LIVEBOOK_ROOT_PATH")
+
 if password = Livebook.Config.password!("LIVEBOOK_PASSWORD") do
   config :livebook, authentication_mode: :password, password: password
 else

lib/livebook/config.ex

@@ -28,13 +28,36 @@ defmodule Livebook.Config do
   """
   @spec root_path() :: binary()
   def root_path() do
-    Application.get_env(:livebook, :root_path, File.cwd!())
+    Application.fetch_env!(:livebook, :root_path)
   end
 
   ## Parsing
 
   @doc """
-  Parses a long secret.
+  Parses and validates the root path from env.
+  """
+  def root_path!(env) do
+    if root_path = System.get_env(env) do
+      root_path!("LIVEBOOK_ROOT_PATH", root_path)
+    else
+      File.cwd!()
+    end
+  end
+
+  @doc """
+  Validates `root_path` within context.
+  """
+  def root_path!(context, root_path) do
+    if File.dir?(root_path) do
+      root_path
+    else
+      IO.warn("ignoring #{context} because it doesn't point to a directory: #{root_path}")
+      File.get_cwd!()
+    end
+  end
+
+  @doc """
+  Parses and validates the secret from env.
   """
   def secret!(env) do
     if secret_key_base = System.get_env(env) do
@@ -50,7 +73,7 @@ defmodule Livebook.Config do
   end
 
   @doc """
-  Parses a port.
+  Parses and validates the port from env.
   """
   def port!(env) do
     if port = System.get_env(env) do
@@ -62,7 +85,7 @@ defmodule Livebook.Config do
   end
 
   @doc """
-  Parses a password.
+  Parses and validates the password from env.
   """
   def password!(env) do
     if password = System.get_env(env) do

lib/livebook_cli/server.ex

@@ -24,6 +24,7 @@ defmodule LivebookCLI.Server do
                     If LIVEBOOK_PASSWORD is set, it takes precedence over token auth
       --sname       Set a short name for the app distributed node
       -p, --port    The port to start the web application on, defaults to 8080
+      --root-path   The root path to use for file selection
 
     The --help option can be given to print this notice.
 
@@ -69,14 +70,20 @@ defmodule LivebookCLI.Server do
     end
   end
 
-  defp args_to_config(args) do
-    {opts, _} =
-      OptionParser.parse!(
-        args,
-        strict: [token: :boolean, port: :integer, name: :string, sname: :string],
-        aliases: [p: :port]
-      )
+  @switches [
+    token: :boolean,
+    port: :integer,
+    name: :string,
+    sname: :string,
+    root_path: :string
+  ]
 
+  @aliases [
+    p: :port
+  ]
+
+  defp args_to_config(args) do
+    {opts, _} = OptionParser.parse!(args, strict: @switches, aliases: @aliases)
     validate_options!(opts)
     opts_to_config(opts, [])
   end
@@ -101,6 +108,11 @@ defmodule LivebookCLI.Server do
     opts_to_config(opts, [{:livebook, LivebookWeb.Endpoint, http: [port: port]} | config])
   end
 
+  defp opts_to_config([{:root_path, root_path} | opts], config) do
+    root_path = Livebook.Config.root_path!("--root-path", root_path)
+    opts_to_config(opts, [{:livebook, :root_path, root_path} | config])
+  end
+
   defp opts_to_config([{:sname, sname} | opts], config) do
     sname = String.to_atom(sname)
     opts_to_config(opts, [{:livebook, :node, {:shortnames, sname}} | config])