Distillery pseudo-plugin for appending git revision and branch (if not master) to a release version

version_builder.exs

defmodule VersionBuilder do

  @doc """
  Returns the current git info, consisting of the current revision and
  the current branch, if it should differ from being "master"
  """
  def git_info do
    "#{git_revision()}#{git_branch()}"
  end

  defp git_revision do
    {revision, 0} = System.cmd("git", ~w(rev-parse --short HEAD))
    "+#{String.trim(revision)}"
  end

  defp git_branch do
    {branches, 0} = System.cmd("git", ~w(branch))
    branch = branches
    |> String.split("\n")
    |> Enum.find(fn(x) -> String.contains?(x, "*") end)
    |> String.replace("*", "")
    |> String.trim()

    case branch do
      "master" -> ""
      other -> "+#{other}"
    end
  end
end