Questions & Help>Questions

Run function on startup

#startup
jeroenhouben

jeroenhouben

Simple question I could not find an answer for…

I want to perform a HTTP request once at startup of my app and log the output. Phoenix app in my case but the question is general really. I don’t need a whole genserver and all, just a function to run… somewhere

Where do I put this code?

6 comments
#startup
3264 6

Marked As Solved

hauleth

hauleth

Add one of task in your supervisor children list. You can use Task.child_spec/1 for that. This is what I am using for such jobs like Slack notifications or systemd notifications.

5
Post #1

Also Liked

entone

entone

You can also use the :ignore return value in a GenServer init callback in your supervision tree, that will run your init callback and then kill/ignore the process after it’s run.

1
Post #2

Last Post!

ityonemo

ityonemo 

defmodule Foo do 

  def go do
    GenServer.start_link(__MODULE__, :ok)
  end

  def init(_) do
    :ignore
  end

end

defmodule Bar do 

  def go do
    GenServer.start_link(__MODULE__, :ok)
  end

  def init(_) do
    {:stop, :reason}
  end

end

defmodule Baz do 

  def go do
    GenServer.start_link(__MODULE__, :ok)
  end

  def init(_) do
    {:stop, :normal}
  end

end

defmodule Quux do

  def go do
    Task.start_link(fn -> :do_something end)
  end

end

try them all in the console to get a feel of what the supervisors see.

0
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