How to determine if app is launched standalone vs in umbrella?

Phoenix Forum Chat / Discussions
1

I’m building an umbrella app where at least some of the apps are Phoenix apps. Most of the time (including in production), I launch the “main” app and have it forward requests to the appropriate child. Sometimes, though, I want to test just this application.

So that means I need the child app’s endpoint to be launched, but only when launching standalone. Right now I’m doing that by sniffing the output of System.get_cwd/0 like this:

was_launched_standalone? = System.cwd |> Path.basename |> String.equivalent?("user")

but that feels hacky. Is there a more appropriate way to ask this question?

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Mix detects wether the current task is executed in umbrella child this way:

https://github.com/elixir-lang/elixir/blob/master/lib/mix/lib/mix/tasks/new.ex#L187

So it looks like they check if grandparent path is umbrella project and current project root is a child app.

If you know the other apps you could also determine if the other app is loaded/started with:

iex(1)> Application.loaded_applications
[{:compiler, 'ERTS  CXC 138 10', '7.0'}, {:logger, 'logger', '1.3.3'},
 {:stdlib, 'ERTS  CXC 138 10', '3.0'}, {:kernel, 'ERTS  CXC 138 10', '5.0'},
 {:elixir, 'elixir', '1.3.3'}, {:iex, 'iex', '1.3.3'}]
iex(2)> Application.started_applications
[{:logger, 'logger', '1.3.3'}, {:iex, 'iex', '1.3.3'},
 {:elixir, 'elixir', '1.3.3'}, {:compiler, 'ERTS  CXC 138 10', '7.0'},
 {:stdlib, 'ERTS  CXC 138 10', '3.0'}, {:kernel, 'ERTS  CXC 138 10', '5.0'}]
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OK, thanks. I’ve since redesigned in such a way as to avoid this question altogether, but this looks helpful.