Why do I get this error `(Mix) Could not find an SCM for dependency :cowboy `

Question

I have a elixir project and below is the mix configuration file:

defmodule MyFirstApp.Mixfile do
  use Mix.Project

  def project do
    [
      app: :my_first_app,
      version: "0.1.0",
      elixir: "~> 1.5",
      start_permanent: Mix.env == :prod,
      deps: deps()
    ]
  end

  # Run "mix help compile.app" to learn about applications.
  def application do
    [
      extra_applications: [:logger],
      mod: {MyFirstApp, []}
    ]
  end

  # Run "mix help deps" to learn about dependencies.
  defp deps do
    [
      # {:dep_from_hexpm, "~> 0.3.0"},
      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"},
      {:cowboy, "~> 1.1.2"},
      {:plug, "~> 1.3.4"},
      {:slime, "~> 0.14"}
    ]
  end
end

I got below error when I run mix deps.get on ubuntu:

mix deps.get
Could not find Hex, which is needed to build dependency :cowboy
Shall I install Hex? (if running non-interactively, use "mix local.hex --force") [Yn] ** (Mix) Could not find an SCM for dependency :cowboy from MyFirstApp.Mixfile
Exited with code 1

I don't understand why happens here. It seems that there is a missing dependency of Hex but how I can install Hex on my system?

Answer 1

You should run mix local.hex on your shell. It will installs Hex locally .

Hex is package manager for the Erlang VM, currently provides tasks that integrate with Mix, Elixir's build tool.