Merge pull request #7971 from rabbitmq/mergify/bp/v3.12.x/pr-7970

CLI: more OTP 26 compatibility for remote_shell (backport #7970)

Author: michaelklishin

deps/rabbitmq_cli/lib/rabbitmq/cli/diagnostics/commands/remote_shell_command.ex

@@ -7,6 +7,7 @@
 defmodule RabbitMQ.CLI.Diagnostics.Commands.RemoteShellCommand do
   @behaviour RabbitMQ.CLI.CommandBehaviour
   @dialyzer :no_missing_calls
+  @dialyzer {:nowarn_function, [run: 2, start_shell_on_otp_26_plus: 1, start_shell_on_otp_25: 1]}
 
   use RabbitMQ.CLI.Core.MergesNoDefaults
   use RabbitMQ.CLI.Core.AcceptsNoPositionalArguments
@@ -15,18 +16,9 @@ defmodule RabbitMQ.CLI.Diagnostics.Commands.RemoteShellCommand do
     _ = :c.l(:shell)
 
     if :erlang.function_exported(:shell, :start_interactive, 1) do
-      :shell.start_interactive({node_name, :shell, :start, []})
-      :timer.sleep(:infinity)
+      start_shell_on_otp_26_plus(node_name)
     else
-      _ = Supervisor.terminate_child(:kernel_sup, :user)
-      Process.flag(:trap_exit, true)
-      user_drv = :user_drv.start(['tty_sl -c -e', {node_name, :shell, :start, []}])
-      Process.link(user_drv)
-
-      receive do
-        {'EXIT', _user_drv, _} ->
-          {:ok, "Disconnected from #{node_name}."}
-      end
+      start_shell_on_otp_25(node_name)
     end
   end
 
@@ -41,4 +33,26 @@ defmodule RabbitMQ.CLI.Diagnostics.Commands.RemoteShellCommand do
   def banner(_, %{node: node_name}) do
     "Starting an interactive Erlang shell on node #{node_name}... Press 'Ctrl+G' then 'q' to exit."
   end
+
+  defp start_shell_on_otp_26_plus(node_name) do
+    case :shell.start_interactive({node_name, {:shell, :start, []}}) do
+      :ok -> :ok
+      {:error, :already_started} -> :ok
+      {error, _} -> {:error, {:badrpc, :nodedown}}
+    end
+
+    :timer.sleep(:infinity)
+  end
+
+  defp start_shell_on_otp_25(node_name) do
+    _ = Supervisor.terminate_child(:kernel_sup, :user)
+    Process.flag(:trap_exit, true)
+    user_drv = :user_drv.start(['tty_sl -c -e', {node_name, :shell, :start, []}])
+    Process.link(user_drv)
+
+    receive do
+      {'EXIT', _user_drv, _} ->
+        {:ok, "Disconnected from #{node_name}."}
+    end
+  end
 end