Always run distribution in long names mode (#2646)

README.md

@@ -220,10 +220,6 @@ The following environment variables can be used to configure Livebook on boot:
     "standalone" (Elixir standalone), "attached:NODE:COOKIE" (Attached node)
     or "embedded" (Embedded). Defaults to "standalone".
 
-  * `LIVEBOOK_DISTRIBUTION` - sets the node distribution for running Livebook in a
-    cluster. Must be "name" (long names) or "sname" (short names). Note that this
-    sets RELEASE_DISTRIBUTION if present when creating a release. Defaults to "sname".
-
   * `LIVEBOOK_EPMDLESS` - if set to "true", it disables the usage of EPMD. This is
     only supported within releases and defaults to true for the Desktop app.
 
@@ -308,9 +304,6 @@ such as:
 
   * [the `PATH` environment variable](https://en.wikipedia.org/wiki/PATH_(variable))
 
-  * set `LIVEBOOK_DISTRIBUTION=name` to enable notebooks to communicate
-    with nodes in other machines
-
   * or to configure the Erlang VM, for instance, by setting
     `ERL_AFLAGS="-proto_dist inet6_tcp"` if you need Livebook to run over IPv6
 

config/test.exs

@@ -28,9 +28,3 @@ config :livebook,
   agent_name: "chonky-cat"
 
 config :livebook, Livebook.Apps.Manager, retry_backoff_base_ms: 0
-
-# Use longnames when running tests in CI, so that no host resolution is required,
-# see https://github.com/livebook-dev/livebook/pull/173#issuecomment-819468549
-if System.get_env("CI") == "true" do
-  config :livebook, :node, {:longnames, :"[email protected]"}
-end

docs/deployment/clustering.md

@@ -1,6 +1,6 @@
 # Clustering
 
-If you plan to run several Livebook instances behind a load balancer, you need to enable clustering via the `LIVEBOOK_CLUSTER` environment variable in your Docker image. `LIVEBOOK_DISTRIBUTION` is automatically set to `name` if clustering is enabled.
+If you plan to run several Livebook instances behind a load balancer, you need to enable clustering via the `LIVEBOOK_CLUSTER` environment variable in your Docker image.
 
 Depending on the clustering strategy of your choice, you must set additional environment variables, oftentimes, at runtime. When using the Livebook Docker image, you can create a file at `/app/user/env.sh` that exports the necessary environment variables. This file is invoked right before booting Livebook.
 

docs/use_cases.md

@@ -44,7 +44,7 @@ system you want to connect to. For example, to connect to a
 you may start it as follows:
 
 ```shell
-$ iex --sname phoenix-app --cookie secret -S mix phx.server
+$ iex --name phoenix-app@127.0.0.1 --cookie secret -S mix phx.server
 ```
 
 With this information in hand, you can query and automate tasks within

lib/livebook.ex

@@ -199,17 +199,23 @@ defmodule Livebook do
       config :livebook, :cacertfile, cacertfile
     end
 
-    if rewrite_on = Livebook.Config.rewrite_on!("LIVEBOOK_PROXY_HEADERS") do
-      config :livebook, :rewrite_on, rewrite_on
-    end
+    config :livebook, :rewrite_on, Livebook.Config.rewrite_on!("LIVEBOOK_PROXY_HEADERS")
 
     config :livebook,
            :cookie,
            Livebook.Config.cookie!("LIVEBOOK_COOKIE") ||
              Livebook.Config.cookie!("RELEASE_COOKIE") ||
              Livebook.Utils.random_cookie()
 
-    if node = Livebook.Config.node!("LIVEBOOK_NODE", "LIVEBOOK_DISTRIBUTION") do
+    # TODO: remove in v1.0
+    if System.get_env("LIVEBOOK_DISTRIBUTION") == "sname" do
+      IO.warn(
+        ~s/Ignoring LIVEBOOK_DISTRIBUTION=sname, because short names are no longer supported./,
+        []
+      )
+    end
+
+    if node = Livebook.Config.node!("LIVEBOOK_NODE") do
       config :livebook, :node, node
     end
 

lib/livebook/application.ex

@@ -13,7 +13,6 @@ defmodule Livebook.Application do
     else
       ensure_epmd!()
       ensure_distribution!()
-      validate_hostname_resolution!()
     end
 
     set_cookie()
@@ -164,9 +163,9 @@ defmodule Livebook.Application do
 
   defp ensure_distribution!() do
     unless Node.alive?() do
-      {type, name} = get_node_type_and_name()
+      node = get_node_name()
 
-      case Node.start(name, type) do
+      case Node.start(node, :longnames) do
         {:ok, _} ->
           :ok
 
@@ -179,88 +178,24 @@ defmodule Livebook.Application do
   import Record
   defrecordp :hostent, Record.extract(:hostent, from_lib: "kernel/include/inet.hrl")
 
-  # See https://github.com/livebook-dev/livebook/issues/302
-  defp validate_hostname_resolution!() do
-    unless Livebook.Config.longname() do
-      [nodename, hostname] = node() |> Atom.to_charlist() |> :string.split(~c"@")
-
-      # erl_epmd names do not support ipv6 resolution by default,
-      # unless inet6 is configured, so we attempt both.
-      gethostbyname =
-        with {:error, _} <- :inet.gethostbyname(hostname, :inet, :infinity),
-             {:error, _} <- :inet.gethostbyname(hostname, :inet6, :infinity),
-             do: :error
-
-      with {:ok, hostent(h_addr_list: [epmd_addr | _])} <- gethostbyname,
-           {:ok, nodenames} <- :erl_epmd.names(epmd_addr),
-           true <- List.keymember?(nodenames, nodename, 0) do
-        :ok
-      else
-        _ ->
-          hint =
-            cond do
-              is_nil(System.get_env("LIVEBOOK_DESKTOP")) ->
-                """
-                  * If you are using Livebook's CLI or from source, consider using longnames:
-
-                        livebook server --name [email protected]
-                        elixir --name [email protected] -S mix phx.server
-                """
-
-              match?({:win32, _}, :os.type()) ->
-                path =
-                  Path.join(
-                    System.get_env("USERPROFILE", "%USERPROFILE%"),
-                    ".livebookdesktop.bat"
-                  )
-
-                """
-                  * Configure your Livebook Desktop to use long names by creating a file at #{path} with:
-
-                        set LIVEBOOK_DISTRIBUTION=name
-                        set [email protected]
-                """
-
-              true ->
-                path = Path.join(System.get_env("HOME", "~"), ".livebookdesktop.sh")
-
-                """
-                  * Configure your Livebook Desktop to use long names by creating a file at #{path} with:
-
-                        export LIVEBOOK_DISTRIBUTION=name
-                        export [email protected]
-                """
-            end
-
-          Livebook.Config.abort!("""
-          Your hostname \"#{hostname}\" does not resolve to a loopback address (127.0.0.0/8), \
-          which indicates something wrong in your OS configuration, or EPMD is not running.
-
-          To address this issue, you might:
-
-            * Consult our Installation FAQ:
-              https://github.com/livebook-dev/livebook/wiki/Installation-FAQ
-
-          #{hint}\
-
-            * If the issue persists, please file a bug report
-
-          """)
-      end
-    end
-  end
-
   defp set_cookie() do
     cookie = Application.fetch_env!(:livebook, :cookie)
     Node.set_cookie(cookie)
   end
 
-  defp get_node_type_and_name() do
-    Application.get_env(:livebook, :node) || {:shortnames, random_short_name()}
+  defp get_node_name() do
+    Application.get_env(:livebook, :node) || random_long_name()
   end
 
-  defp random_short_name() do
-    :"livebook_#{Livebook.Utils.random_short_id()}"
+  defp random_long_name() do
+    host =
+      if Livebook.Utils.proto_dist() == :inet6_tcp do
+        "::1"
+      else
+        "127.0.0.1"
+      end
+
+    :"livebook_#{Livebook.Utils.random_short_id()}@#{host}"
   end
 
   defp display_startup_info() do

lib/livebook/config.ex

@@ -64,18 +64,6 @@ defmodule Livebook.Config do
     ]
   end
 
-  @doc """
-  Returns the longname if the distribution mode is configured to use long names.
-  """
-  @spec longname() :: binary() | nil
-  def longname() do
-    host = Livebook.Utils.node_host()
-
-    if host =~ "." do
-      host
-    end
-  end
-
   @doc """
   Returns the default runtime.
   """
@@ -532,21 +520,11 @@ defmodule Livebook.Config do
   end
 
   @doc """
-  Parses node and distribution type from env.
+  Parses node from env.
   """
-  def node!(node_env, distribution_env) do
-    case {System.get_env(node_env), System.get_env(distribution_env, "sname")} do
-      {nil, _} ->
-        nil
-
-      {name, "name"} ->
-        {:longnames, String.to_atom(name)}
-
-      {sname, "sname"} ->
-        {:shortnames, String.to_atom(sname)}
-
-      {_, other} ->
-        abort!(~s(#{distribution_env} must be one of "name" or "sname", got "#{other}"))
+  def node!(env) do
+    if node = System.get_env(env) do
+      String.to_atom(node)
     end
   end
 

lib/livebook/runtime/elixir_standalone.ex

@@ -140,8 +140,8 @@ defmodule Livebook.Runtime.ElixirStandalone do
   # Also note that we explicitly halt, just in case `System.no_halt(true)` is
   # called within the runtime.
   @child_node_eval_string """
-  {:ok, [[mode, node]]} = :init.get_argument(:livebook_current);\
-  {:ok, _} = :net_kernel.start(List.to_atom(node), %{name_domain: List.to_atom(mode)});\
+  {:ok, [[node]]} = :init.get_argument(:livebook_current);\
+  {:ok, _} = :net_kernel.start(List.to_atom(node), %{name_domain: :longnames});\
   {:ok, [[parent_node, _port]]} = :init.get_argument(:livebook_parent);\
   dist_port = :persistent_term.get(:livebook_dist_port, 0);\
   init_ref = make_ref();\
@@ -164,8 +164,6 @@ defmodule Livebook.Runtime.ElixirStandalone do
     parent_name = node()
     parent_port = Livebook.EPMD.dist_port()
 
-    mode = if Livebook.Config.longname(), do: :longnames, else: :shortnames
-
     epmdless_flags =
       if parent_port != 0 do
         "-epmd_module Elixir.Livebook.EPMD -start_epmd false -erl_epmd_port 0 "
@@ -181,8 +179,9 @@ defmodule Livebook.Runtime.ElixirStandalone do
       # Enable ANSI escape codes as we handle them with HTML.
       # Disable stdin, so that the system process never tries to read terminal input.
       "+sbwt none +sbwtdcpu none +sbwtdio none +sssdio 128 -elixir ansi_enabled true -noinput " <>
+        "-proto_dist #{Livebook.Utils.proto_dist()} " <>
         epmdless_flags <>
-        "-livebook_parent #{parent_name} #{parent_port} -livebook_current #{mode} #{node_name}",
+        "-livebook_parent #{parent_name} #{parent_port} -livebook_current #{node_name}",
       # Add the location of Livebook.EPMD
       "-pa",
       Application.app_dir(:livebook, "priv/epmd"),

lib/livebook/utils.ex

@@ -133,6 +133,18 @@ defmodule Livebook.Utils do
     host
   end
 
+  @doc """
+  Returns the protocol for Erlang distribution used by the current node.
+  """
+  @spec proto_dist() :: :inet_tcp | :inet6_tcp | :inet_tls
+  def proto_dist() do
+    case :init.get_argument(:proto_dist) do
+      {:ok, [[~c"inet6_tcp"]]} -> :inet6_tcp
+      {:ok, [[~c"inet_tls"]]} -> :inet_tls
+      _ -> :inet_tcp
+    end
+  end
+
   @doc """
   Registers the given process under `name` for the time of `fun` evaluation.
   """

lib/livebook_cli/server.ex

@@ -44,7 +44,6 @@ defmodule LivebookCLI.Server do
                            Must be a valid IPv4 or IPv6 address
       --name               Sets a name for the app distributed node
       -p, --port           The port to start the web application on, defaults to 8080
-      --sname              Sets a short name for the app distributed node
 
     The --help option can be given to print this notice.
 
@@ -195,24 +194,15 @@ defmodule LivebookCLI.Server do
     ip: :string,
     name: :string,
     port: :integer,
-    home: :string,
-    sname: :string
+    home: :string
   ]
 
   @aliases [
     p: :port
   ]
 
   defp args_to_options(args) do
-    {opts, extra_args} = OptionParser.parse!(args, strict: @switches, aliases: @aliases)
-    validate_options!(opts)
-    {opts, extra_args}
-  end
-
-  defp validate_options!(opts) do
-    if Keyword.has_key?(opts, :name) and Keyword.has_key?(opts, :sname) do
-      raise "the provided --sname and --name options are mutually exclusive, please specify only one of them"
-    end
+    OptionParser.parse!(args, strict: @switches, aliases: @aliases)
   end
 
   defp opts_to_config([], config), do: config
@@ -230,14 +220,9 @@ defmodule LivebookCLI.Server do
     ])
   end
 
-  defp opts_to_config([{:sname, sname} | opts], config) do
-    sname = String.to_atom(sname)
-    opts_to_config(opts, [{:livebook, :node, {:shortnames, sname}} | config])
-  end
-
   defp opts_to_config([{:name, name} | opts], config) do
     name = String.to_atom(name)
-    opts_to_config(opts, [{:livebook, :node, {:longnames, name}} | config])
+    opts_to_config(opts, [{:livebook, :node, name} | config])
   end
 
   defp opts_to_config([{:cookie, cookie} | opts], config) do

lib/livebook_web/live/session_live/attached_live.ex

@@ -60,11 +60,7 @@ defmodule LivebookWeb.SessionLive.AttachedLive do
         Make sure to give the node a name and a cookie, for example:
       </p>
       <div class="text-gray-700 markdown">
-        <%= if longname = Livebook.Config.longname() do %>
-          <pre><code>iex --name test@<%= longname %> --cookie mycookie -S mix</code></pre>
-        <% else %>
-          <pre><code>iex --sname test --cookie mycookie -S mix</code></pre>
-        <% end %>
+        <pre><code>iex --name <%= test_node() %> --cookie mycookie -S mix</code></pre>
       </div>
       <p class="text-gray-700">
         Then enter the connection information below:
@@ -79,7 +75,7 @@ defmodule LivebookWeb.SessionLive.AttachedLive do
         spellcheck="false"
       >
         <div class="flex flex-col space-y-4 mb-5">
-          <.text_field field={f[:name]} label="Name" placeholder={name_placeholder()} />
+          <.text_field field={f[:name]} label="Name" placeholder={test_node()} />
           <.text_field field={f[:cookie]} label="Cookie" placeholder="mycookie" />
         </div>
         <.button type="submit" disabled={not @changeset.valid?}>
@@ -138,7 +134,7 @@ defmodule LivebookWeb.SessionLive.AttachedLive do
     changeset.valid? and changeset.data == apply_changes(changeset)
   end
 
-  defp name_placeholder do
-    if longname = Livebook.Config.longname(), do: "test@#{longname}", else: "test"
+  defp test_node() do
+    "test@#{Livebook.Utils.node_host()}"
   end
 end

rel/app/env.bat.eex

@@ -13,8 +13,7 @@ set ELIXIR_ERL_OPTIONS=!ELIXIR_ERL_OPTIONS! -epmd_module Elixir.Livebook.EPMD -s
 :continue
 for /f "skip=1" %%X in ('wmic os get localdatetime') do if not defined TIMESTAMP set TIMESTAMP=%%X
 
-if defined LIVEBOOK_DISTRIBUTION set RELEASE_DISTRIBUTION=!LIVEBOOK_DISTRIBUTION!
-if not defined RELEASE_DISTRIBUTION set RELEASE_DISTRIBUTION=sname
+set RELEASE_DISTRIBUTION="name"
 
 if defined LIVEBOOK_NODE set RELEASE_NODE=!LIVEBOOK_NODE!
 if not defined RELEASE_NODE set RELEASE_NODE=livebook-app-!TIMESTAMP:~8,6!-!RANDOM!

rel/app/env.sh.eex

@@ -2,7 +2,7 @@ if [ -f "$HOME/.livebookdesktop.sh" ]; then
   . "$HOME/.livebookdesktop.sh"
 fi
 
-export RELEASE_DISTRIBUTION=${LIVEBOOK_DISTRIBUTION:-${RELEASE_DISTRIBUTION:-"sname"}}
+export RELEASE_DISTRIBUTION="name"
 export RELEASE_NODE=${LIVEBOOK_NODE:-${RELEASE_NODE:-"livebook-app-$(cat /dev/urandom | env LC_ALL=C tr -dc 'a-zA-Z0-9' | fold -w 8 | head -n 1)"}}
 export RELEASE_MODE=interactive
 export MIX_ARCHIVES="${RELEASE_ROOT}/vendor/archives"