An Elixir port of the node.js module 'gravatar-url'. People often ask «where are the packages for Elixir?» Often the answer is «they are baked in; for anything else try out Hex.pm»

gravatar.ex

defmodule Gravatar do
  @base_url "https://secure.gravatar.com/avatar/"

  @doc """
  Will get the corresponding gravatar url for a given email address. Options
  can be passed in using a keyword list or a map.

    iex> Gravatar.url("martin@gausby.dk", size: 200)
    https://secure.gravatar.com/avatar/0e6a9f19e77fa18bf6f185258f2507d6?size=200

  Read this site for a list of options:
  https://secure.gravatar.com/site/implement/images/
  """
  @spec url(String.t, Map) :: String.t
  def url(email, opts \\ []) do
    email = String.downcase(email)
    hash = :crypto.hash(:md5, email) |> Base.encode16(case: :lower)
    "#{@base_url}#{hash}?#{URI.encode_query(opts)}"
  end
end

If you are looking for a gravatar module for your own Elixir project you should check out https://github.com/scrogson/exgravatar