Get app versions at compile time?

I doubt any measurable performance drawbacks will occur with the following

<%= Application.get_env(:ex, :env) %>:<%= Application.spec(:ex, :vsn) %>

I’m not sure it is expensive (a benchmark would give us some clues here), I haven’t noticed any timing issue when running my app with :application.get_key(:myapp, :vsn)

I like this – but it seems undefined at compile?

for me, this works very well:

{:ok, version} = :application.get_key(:myapp, :vsn)
Logger.info("Application xxx #{version}: started")

you may want to use elem/2 instead of Tuple.to_list |> Tuple.at

I found solution to this: just add mix.lock to .formatter.exs:

[
  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}", "mix.lock"]
]

and then the above works!

Ah, of course I did not think of this!

"mix.lock"
  |> Code.eval_file()
  |> Tuple.to_list()
  |> Enum.at(0)
  |> Enum.reduce(%{}, fn
    {app, {:hex, _, version, _, _, _, _, _}}, acc ->
      Map.put(acc, app, version)

    {app, {:git, _, _, [{_, version}]}}, acc ->
      Map.put(acc, app, version)
  end)

However this has lots of warnings: warning: found quoted keyword "jason" but the quotes are not required.

Is there a way to avoidthose?

Is this on purpose that the mix.lock contains bad format? Shouldn’t have no quotes for keys or use =>?

it just occurred to me that won’t tell you what the version is, just what version you wanted. You could also read the mix.lock file using Code.eval_file/1

your MixProject module is nothing special, it’s a module like any other (I mean aside from the fact that it’s only available at compile time). Make the deps/0 function public instead of private, and you’re good to go.

Oiy, is almost working – this does not work for mix compile
maybe I have to do something in application start?