Generate S3 signed URL with Elixir

generate-s3-signed-url.ex

defmodule Famiby.Helpers.AWS do
  alias Famiby.Helpers

  @bucket_name Application.get_env(:ex_aws, :bucket)
  @region Application.get_env(:ex_aws, :region)
  @env Application.get_env(:famiby, :env)

  def s3_signed_url(filename, acl \\ "public-read") do
    key = "#{@env}/#{filename}"
    content_type = Helpers.File.file_type(filename)
    query_params = [
      {"ContentType", content_type},
      {"x-amz-acl", acl}
    ]
    presign_options = [virtual_host: false, query_params: query_params]

    case ExAws.Config.new(:s3) |> ExAws.S3.presigned_url(:put, @bucket_name, key, presign_options) do
      {:ok, url} -> {:ok, %{file_url: s3_url(key), signed_url: url, content_type: content_type}}
      err -> err
    end
  end

  def s3_url(key) do
    "http://#{@bucket_name}.s3-#{@region}.amazonaws.com/#{key}"
  end
end