59 lines
1.9 KiB
Elixir
59 lines
1.9 KiB
Elixir
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defmodule Envars do
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@moduledoc """
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`Envars` provides a convenience function to fetch and parse environment
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variables all in once place. This has the benefit of also providing an error
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message listing all missing required values.
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## Example
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%{
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"PORT" => port,
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"ENABLE_SSL" => enable_ssl,
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"AWS_ACCESS_KEY_ID" => access_key_id,
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"PHX_HOST" => phx_host
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} = Envars.read!(%{
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"PORT" => [type: :integer, required: false, default: 4000],
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"ENABLE_SSL" => [type: :boolean],
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"AWS_ACCESS_KEY_ID" => [type: :string],
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"PHX_HOST" => [type: :string]
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})
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"""
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@type field_type :: :string | :integer | :boolean
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@type options :: [
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{:type, field_type()} | {:required, boolean()} | {:default, term()}
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]
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@spec read!(fields :: %{(field :: String.t()) => options()}) :: %{String.t() => term()}
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def read!(fields) do
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{valid, invalid} =
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for {field, opts} <- fields do
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type = Keyword.get(opts, :type, :string)
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required = Keyword.get(opts, :required, true)
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default = Keyword.get(opts, :default)
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value = System.get_env(field)
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case {value, required, default} do
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{nil, true, nil} -> {:error, {field, :undefined}}
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{nil, _, default} -> {:ok, {field, default}}
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{value, _, _} -> {:ok, {field, parse(type, value)}}
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end
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end
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|> Enum.split_with(&(elem(&1, 0) == :ok))
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if Enum.empty?(invalid) do
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for {:ok, {field, value}} <- valid, into: %{}, do: {field, value}
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else
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missing_fields = for {:error, {field, _}} <- invalid, do: field
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raise "Missing environment variables:\n\n - #{Enum.join(missing_fields, "\n - ")}"
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end
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end
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defp parse(:string, value), do: value
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defp parse(:integer, value), do: String.to_integer(value)
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defp parse(:boolean, "0"), do: false
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defp parse(:boolean, "1"), do: true
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defp parse(:boolean, value), do: String.downcase(value) == "true"
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end
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