Command to print last N log messages from the default log.

deps/rabbitmq_cli/lib/rabbitmq/cli/core/log_files.ex

@@ -0,0 +1,61 @@
+## The contents of this file are subject to the Mozilla Public License
+## Version 1.1 (the "License"); you may not use this file except in
+## compliance with the License. You may obtain a copy of the License
+## at https://www.mozilla.org/MPL/
+##
+## Software distributed under the License is distributed on an "AS IS"
+## basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+## the License for the specific language governing rights and
+## limitations under the License.
+##
+## The Original Code is RabbitMQ.
+##
+## The Initial Developer of the Original Code is GoPivotal, Inc.
+## Copyright (c) 2019 Pivotal Software, Inc.  All rights reserved.
+
+defmodule RabbitMQ.CLI.Core.LogFiles do
+  @spec get_log_locations(atom, integer | :infinity) :: [String.t] | {:badrpc, term}
+  def get_log_locations(node_name, timeout) do
+    case :rabbit_misc.rpc_call(node_name,
+                               :rabbit_lager, :log_locations, [],
+                               timeout) do
+      {:badrpc, _} = error -> error;
+      list -> Enum.map(list, &to_string/1)
+    end
+  end
+
+  @spec get_default_log_location(atom, integer | :infinity) ::
+    {:ok, String.t} | {:badrpc, term} | {:error, term}
+  def get_default_log_location(node_name, timeout) do
+    case get_log_locations(node_name, timeout) do
+      {:badrpc, _} = error -> error;
+      [] -> {:error, "No log files configured on the node"};
+      [first_log | _] = log_locations ->
+        case get_log_config_file_location(node_name, timeout) do
+          {:badrpc, _} = error -> error;
+          nil      -> {:ok, first_log};
+          location ->
+            case Enum.member?(log_locations, location) do
+              true  -> {:ok, to_string(location)};
+              ## Configured location was not propagated to lager?
+              false -> {:ok, first_log}
+            end
+        end
+    end
+  end
+
+  defp get_log_config_file_location(node_name, timeout) do
+    case :rabbit_misc.rpc_call(node_name,
+                               :application, :get_env, [:rabbit, :log, :none],
+                               timeout) do
+      {:badrpc, _} = error -> error;
+      :none      -> nil;
+      log_config ->
+        case log_config[:file] do
+          nil -> nil;
+          file_config ->
+            file_config[:file]
+        end
+    end
+  end
+end

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

@@ -19,6 +19,8 @@ defmodule RabbitMQ.CLI.Diagnostics.Commands.LogLocationCommand do
   """
   @behaviour RabbitMQ.CLI.CommandBehaviour
 
+  alias RabbitMQ.CLI.Core.LogFiles
+
   def switches, do: [all: :boolean]
   def aliases, do: [a: :all]
 
@@ -29,44 +31,9 @@ defmodule RabbitMQ.CLI.Diagnostics.Commands.LogLocationCommand do
   use RabbitMQ.CLI.Core.AcceptsNoPositionalArguments
 
   def run([], %{node: node_name, timeout: timeout, all: all}) do
-    case :rabbit_misc.rpc_call(node_name,
-                               :rabbit_lager, :log_locations, [],
-                               timeout) do
-      {:badrpc, _} = error ->
-        error;
-      ## No log files?
-      [] -> {:error, "No log files configured on the node"};
-      [first_log | _] = log_locations ->
-        case all do
-          true  -> log_locations;
-          false ->
-            ## Select the "main" file
-            case get_log_config_file_location(node_name, timeout) do
-              {:badrpc, _} = error -> error;
-              nil      -> to_string(first_log);
-              location ->
-                case Enum.member?(log_locations, location) do
-                  true  -> to_string(location);
-                  ## Configured location was not propagated to lager?
-                  false -> to_string(first_log)
-                end
-            end
-        end
-    end
-  end
-
-  def get_log_config_file_location(node_name, timeout) do
-    case :rabbit_misc.rpc_call(node_name,
-                               :application, :get_env, [:rabbit, :log, :none],
-                               timeout) do
-      {:badrpc, _} = error -> error;
-      :none      -> nil;
-      log_config ->
-        case log_config[:file] do
-          nil -> nil;
-          file_config ->
-            file_config[:file]
-        end
+    case all do
+      true  -> LogFiles.get_log_locations(node_name, timeout);
+      false -> LogFiles.get_default_log_location(node_name, timeout)
     end
   end
 
@@ -76,7 +43,7 @@ defmodule RabbitMQ.CLI.Diagnostics.Commands.LogLocationCommand do
 
   def description(), do: "Shows the log file location(s) on the target node"
 
-  def usage, do: "log_location"
+  def usage, do: "log_location [--all|-a]"
 
   def banner([], %{node: node_name}) do
     "Log file location on node #{node_name} ..."

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

@@ -0,0 +1,59 @@
+## The contents of this file are subject to the Mozilla Public License
+## Version 1.1 (the "License"); you may not use this file except in
+## compliance with the License. You may obtain a copy of the License
+## at https://www.mozilla.org/MPL/
+##
+## Software distributed under the License is distributed on an "AS IS"
+## basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+## the License for the specific language governing rights and
+## limitations under the License.
+##
+## The Original Code is RabbitMQ.
+##
+## The Initial Developer of the Original Code is GoPivotal, Inc.
+## Copyright (c) 2019 Pivotal Software, Inc.  All rights reserved.
+
+defmodule RabbitMQ.CLI.Diagnostics.Commands.LogTailCommand do
+  @moduledoc """
+  Displays standard log file location on the target node
+  """
+  @behaviour RabbitMQ.CLI.CommandBehaviour
+
+  alias RabbitMQ.CLI.Core.LogFiles
+
+  def switches, do: [number: :integer]
+  def aliases, do: ['N': :number]
+
+  def merge_defaults(args, opts) do
+    {args, Map.merge(%{number: 10}, opts)}
+  end
+  use RabbitMQ.CLI.Core.AcceptsNoPositionalArguments
+
+  def run([], %{node: node_name, timeout: timeout, number: n}) do
+    case LogFiles.get_default_log_location(node_name, timeout) do
+      {:ok, file} ->
+        :rabbit_misc.rpc_call(node_name,
+                              :rabbit_log_tail, :tail_n_lines, [file, n],
+                              timeout)
+      error -> error
+    end
+  end
+
+  use RabbitMQ.CLI.DefaultOutput
+
+  def help_section(), do: :configuration
+
+  def description(), do: "Prints the last N lines of the log on the node"
+
+  def usage, do: "log_tail [--number|-N <number>]"
+
+  def usage_additional do
+    [
+      ["<number>", "number of lines to print. 10 by default"]
+    ]
+  end
+
+  def banner([], %{node: node_name, number: n}) do
+    "Last #{n} lines of the log on node #{node_name} ..."
+  end
+end

deps/rabbitmq_cli/lib/rabbitmqctl.ex

@@ -510,7 +510,7 @@ defmodule RabbitMQCtl do
   defp format_error({:error, :check_failed, err}, %{formatter: "json"}, _) do
     {:error, ExitCodes.exit_unavailable(), err}
   end
-  defp format_error({:error, :check_failed}, _, _) do
+  defp format_error({:error, :check_failed, _}, _, _) do
     {:error, ExitCodes.exit_unavailable(), nil}
   end