require 'zlib'
require 'rubygems/package'
require 'open-uri'

# Download file here
mirror = 'http://nl.alpinelinux.org/alpine'
uri = "#{mirror}/edge/main/x86_64/APKINDEX.tar.gz"

archive = open(uri)

Zlib::GzipReader.open(archive) do |gz|
  Gem::Package::TarReader.new(gz) do |tar|
    tar.each { |entry| puts entry.full_name  }
  end
end