The application is not listed in observer
<p>Although the phenix server starts normally, but I can't see it in the applications list at the observer.</p>

<p>What I did is:</p>

<pre><code>elixir -S mix phoenix.server
</code></pre>

<p>And, it another terminal:</p>

<pre><code>iMac:~ Apple$ iex
Erlang/OTP 18 [erts-7.3] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false] [dtrace]

Interactive Elixir (1.2.4) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)&gt; :observer.start
:ok
</code></pre>

<p>Here is how my app is started:</p>

<pre><code>defmodule Rumbl do
  use Application

  # See http://elixir-lang.org/docs/stable/elixir/Application.html
  # for more information on OTP Applications
  def start(_type, _args) do
    import Supervisor.Spec, warn: false

    children = [
      # Start the endpoint when the application starts
      supervisor(Rumbl.Endpoint, []),
      # Start the Ecto repository
      supervisor(Rumbl.Repo, []),
      # Here you could define other workers and supervisors as children
      # worker(Rumbl.Worker, [arg1, arg2, arg3]),
    ]

    # See http://elixir-lang.org/docs/stable/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: Rumbl.Supervisor]
    Supervisor.start_link(children, opts)
  end

  # Tell Phoenix to update the endpoint configuration
  # whenever the application is updated.
  def config_change(changed, _new, removed) do
    Rumbl.Endpoint.config_change(changed, removed)
    :ok
  end
end
</code></pre>

<p>The observer:
<a href="https://i.stack.imgur.com/4xhpV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4xhpV.png" alt="enter image description here"></a></p>

<p>So, why I can't see it in observer?</p>

<p><strong>EDIT</strong></p>

<p>I clicked on Nodes in the observer, then "enable distribution" , then nodes appeared, but once I chose rumbl node, I get an error:</p>

<pre><code>11:17:11.379 [error] [node: :rumbl@iMac, call: {:observer_backend, :sys_info, []}, reason: {:badrpc, :nodedown}]
</code></pre>

<p>although the node is up and running:</p>

<pre><code>$ elixir --name rumbl -S mix phoenix.server
[info] Running Rumbl.Endpoint with Cowboy using http on port 4000
14 May 11:10:33 - info: compiled 5 files into 2 files, copied 3 in 2.9 sec
[info] GET /
[debug] Processing by Rumbl.PageController.index/2
  Parameters: %{}
  Pipelines: [:browser]
[info] Sent 200 in 104ms
</code></pre>

<p>I tried to chose rumbl@iMac again, then I got error:</p>

<pre><code>Child (unknown) crashed exiting:  &lt;0.67.0&gt; {{badmatch,{badrpc,nodedown}},
                                            [{observer_app_wx,handle_info,2,
                                              [{file,"observer_app_wx.erl"},
                                               {line,283}]},
                                             {wx_object,handle_msg,5,
                                              [{file,"wx_object.erl"},
                                               {line,432}]},
                                             {proc_lib,init_p_do_apply,3,
                                              [{file,"proc_lib.erl"},
                                               {line,240}]}]}
iex(2)&gt; 
11:19:56.534 [error] ** wx object server #PID&lt;0.67.0&gt; terminating 
** Last message in was {:active, :rumbl@iMac}
** When Server state == {:state, #PID&lt;0.59.0&gt;, {:wx_ref, 327, :wxPanel, []},
 {:wx_ref, 330, :wxListBox, []}, {:wx_ref, 333, :wxScrolledWindow, []},
 {:paint, {:wx_ref, 342, :wxFont, []}, {:wx_ref, 346, :wxPen, []},
  {:wx_ref, 343, :wxBrush, []}, {:wx_ref, 344, :wxBrush, []},
  {:wx_ref, 345, :wxPen, []}}, :elixir,
 {:app,
  {{:box, 16, 47, 57, 23, {:str, 5, 5, '&lt;0.35.0&gt;', #PID&lt;0.35.0&gt;}},
   [{{:box, 89, 47, 58, 23, {:str, 5, 5, '&lt;0.36.0&gt;', #PID&lt;0.36.0&gt;}},
     [{{:box, 163, 47, 58, 23, {:str, 5, 5, 'elixir_sup', #PID&lt;0.37.0&gt;}},
       [{{:box, 237, 12, 103, 23,
          {:str, 5, 5, 'elixir_code_server', #PID&lt;0.39.0&gt;}}, []},
        {{:box, 237, 47, 72, 23, {:str, 5, 5, 'elixir_config', #PID&lt;0.38.0&gt;}},
         []},
        {{:box, 237, 82, 80, 23, {:str, 5, 5, 'elixir_counter', #PID&lt;0.40.0&gt;}},
         []}]}]}]}, :undefined, [], {356, 117}}, :undefined, :undefined, true}
** Reason for termination == 
** {{:badmatch, {:badrpc, :nodedown}},
 [{:observer_app_wx, :handle_info, 2, [file: 'observer_app_wx.erl', line: 283]},
  {:wx_object, :handle_msg, 5, [file: 'wx_object.erl', line: 432]},
  {:proc_lib, :init_p_do_apply, 3, [file: 'proc_lib.erl', line: 240]}]}


11:19:56.549 [error] GenServer :appmon_info terminating
** (MatchError) no match of right hand side value: {:badrpc, :nodedown}
    observer_app_wx.erl:283: :observer_app_wx.handle_info/2
    wx_object.erl:432: :wx_object.handle_msg/5
    (stdlib) proc_lib.erl:240: :proc_lib.init_p_do_apply/3
Last message: {:EXIT, #PID&lt;0.67.0&gt;, {{:badmatch, {:badrpc, :nodedown}}, [{:observer_app_wx, :handle_info, 2, [file: 'observer_app_wx.erl', line: 283]}, {:wx_object, :handle_msg, 5, [file: 'wx_object.erl', line: 432]}, {:proc_lib, :init_p_do_apply, 3, [file: 'proc_lib.erl', line: 240]}]}}
State: {:state, #PID&lt;0.67.0&gt;, [], 20507, [#PID&lt;0.67.0&gt;]}
</code></pre>

<p><strong>Fixed</strong></p>

<p>When I enable "enable distribution", I have have entered the same cookie used in the rumbl node as:</p>

<pre><code>elixir --sname rumbl --cookie secret_token -S mix phoenix.server
</code></pre>

<p>then, I chose rumbl node and all apps are listed!</p>