---

observer_cli

Visualize Erlang/Elixir Nodes On The Command Line base on recon. Document in detail.

Goal

• Provide a high-performance tool usable both in development and production settings.
• Focus on important and detailed information about real-time running system.
• Keep minimal consumption.

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Installation

Erlang

%% rebar.config
{deps, [observer_cli]}
%% erlang.mk
dep_observer_cli = hex 1.5.3

Elixir

# mix.exs
   def deps do
     [{:observer_cli, "~> 1.5"}]
   end

---

How-To

Try in local shell.

%% rebar3 project
rebar3 shell
1> observer_cli:start().
%% mix project
iex -S mix
iex(1)> :observer_cli.start

Monitor remote node

%% rebar3 project
rebar3 shell --name '[email protected]'
1> observer_cli:start('target@host', 'magic_cookie').
%% mix project
iex --name "[email protected]" -S mix
iex(1)> :observer_cli.start(:'target@host', :'magic_cookie')

❗ ensure observer_cli application been loaded on target node.

Try in Elixir 1.9.x release

%% create elixir release
mix release
%% rpc current node
_build/dev/rel/example/bin/example rpc ":observer_cli.start"

❗ ensure observer_cli application been loaded on current node.

Escriptize

1. cd path/to/observer_cli/
2. rebar3 escriptize to generate an escript executable containing the project's and its dependencies' BEAM files. Place script(_build/default/bin/observer_cli) anywhere in your path and use observer_cli command.
3. observer_cli TARGETNODE [TARGETCOOKIE REFRESHMS] to monitor remote node.

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DEMO

How to write your own plugin?

If you need to customize some of your internal metrics and integrate it into observer_ci, you only need to write a observer_cli_plugin behaviour in a few simple steps to get a nice presentation.

1. Configure observer_cli，tell observer_cli how to find your plugin.

%% module       - Specific module implements plugin behavior. It's mandatory.
%% title        - Menu title. It's mandatory.
%% shortcut     - Switch plugin by shortcut. It's mandatory.
%% interval     - Refresh interval ms. It's optional. default is 1500ms.
%% sort_column  - Sort the sheet by this index. It's optional default is 2.

{plugins,
  [
    #{module => observer_cli_plug_behaviour1, title => "XPlug",
      interval => 1500, shortcut => "X", sort_column => 3},
    #{module => observer_cli_plug_behaviour2, title => "YPlug",
      interval => 1600, shortcut => "Y", sort_column => 3}
  ]
}

2. Write observer_cli_plugin behaviour. observer_cli_plugin has 3 callbacks.

2.1 attributes.

-callback atributes(PrevState) -> {[Rows], NewState} when
    Rows :: #{content => string()|integer()|{byte, pos_integer()},
              width => pos_integer(), color => binary()}.

for example:

attributes(PrevState) ->
    Attrs =
    [
        [
            #{content => "XXX Ets Size", width => 20},
            #{content => ets:info(xxx,size), width => 10},
            #{content => "Pool1 Size", width => 15},
            #{content => application:get_env(app,pool1_size), width => 30},
            #{content => "XYZ1 Process Mem", width => 18,
            #{content => {byte, element(2, erlang:process_info(xyz1, memory))}, width => 16}
        ],
        [
            #{content => "YYY Ets Size", width =>20},
            #{content => ets:info(yyy,size), width => 10},
            #{content => "Pool2 Size", width =>15},
            #{content => application:get_env(app,pool2_size), width => 30},
            #{content =>"XYZ2 Process Mem", width =>18},
            #{content => {byte, element(2, erlang:process_info(xyz2, memory))}, width => 16}
        ],
        [
            #{content => "ZZZ Ets Size", width =>20},
            #{content => ets:info(zzz,size), width => 10},
            #{content => "Pool3 Size", width =>15},
            #{content => application:get_env(app,pool3_size), width => 30},
            #{content => "XYZ3 Process Mem", width =>18},
            #{content => {byte, element(2, erlang:process_info(xyz3, memory))}, width => 16}
        ]
    ],
    NewState = PrevState,
    {Attrs, NewState}.

-callback sheet_header() -> [SheetHeader] when
    SheetHeader :: #{title => string(), width => pos_integer(), shortcut => string()}.

for example:

sheet_header() ->
    [
        #{title => "Pid", width => 25},
        #{title => "Status", width => 25},
        #{title => "Memory", width => 24, shortcut => "S"},
        #{title => "Reductions", width => 24, shortcut => "R"},
        #{title => "Message Queue Len", width => 25, shortcut => "Q"}
    ].

-callback sheet_body(PrevState) -> {[SheetBody], NewState} when
    PrevState :: any(),
    SheetBody :: list(),
    NewState :: any().

for example:

sheet_body(PrevState) ->
    Body =
      [begin
         [
             Pid,
             element(2, erlang:process_info(Pid, status)),
             element(2, erlang:process_info(Pid, memory)),
             element(2, erlang:process_info(Pid, reductions)),
             element(2, erlang:process_info(Pid, message_queue_len))
         ]
     end||Pid <- erlang:processes()
    ],
    NewState = PrevState,
    {Body, NewState}.

Support F/B to page up/down.

A more specific plugin can collect linux system information such as kernel vsn, loadavg, disk, memory usage, cpu utilization, IO statistics.

---

Changelog

• 1.5.2

  • Use erlang:system_info(otp_release) when can't find OTP_VERSION file for the full version.

• 1.5.1

  • Hide mnesia tab when it's not started
  • Show specific erl version such as '22.0.5'

• 1.5.0

  • Bump Recon to 2.5.0

• 1.4.5

  • Include a minimal mix.exs build file
  • Make sure EXIT message has been clear

• 1.4.4

  • Make sure connection errors can be handled

• 1.4.3

  • Bump Recon to 2.4.0

• 1.4.2

  • Hidden schedule process bar when core > 100.
  • Allow to compile escript w/ inet6 based distribution.
  • Rewrite plugin callback, rename kv_label/0 to attributes/1.

• 1.4.1

  • Fixed ets view memory usage wrong.
  • mnesia view memory usage According to bytes.

• 1.4.0

  • Support write your own plugin.

• 1.3.4

  • View(ets mnesia) support page down/up; support sort by memory or size.
  • Fixed pause crash.
  • Make refresh interval configurable.

• 1.3.3

  • fixed io:format(Format,Args) Format not support iolist OTP R21

• 1.3.2

  • Make sure all observer_cli process exit when quit.
  • Upgrade recon to 2.3.6

• 1.3.1

  • Add atom limit/count in home.
  • Escript support short name and long name.
  • Fixed store process not exit.
  • Upgrade recon to 2.3.5

• 1.3.0

  • Rewrite Network/Process view.
  • Support PageDown/PageUp for top n list.
  • Escript auto load observer_cli when it's not load on target node.

• 1.2.2

  • fix schedule number >= 32 display wrong.
  • improve memory(byte/kilobyte/megabyte/gigabyte) unit.

• 1.2.1

  • fixed autosize not work.
  • try best to make color adjust all platform.

• 1.2.0

  • add application GUI.
  • Rearrange GUI and optimize render.
  • Always automatically adapt to the window size.

• 1.1.0

  • Support escript, observer_cli <TARGETNODE> <COOKIE>

• 1.0.9

  • Upgrade rebar3 to 3.3.3 for publish hex repo.

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Contributors

zhongwencool 💻	Dimitrios Zorbas 💻	taotao 💻	Trevor Brown 💻	Zaiming Shi 💻

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License

See the LICENSE file for license rights and limitations (MIT).