Ruby HTTP file download with progress measurement

download-progress.rb

require 'net/http'
require 'uri'

def download(url)
  Thread.new do
    thread = Thread.current
    body = thread[:body] = []
    
    url = URI.parse url
    Net::HTTP.new(url.host, url.port).request_get(url.path) do |response|
      length = thread[:length] = response['Content-Length'].to_i

      response.read_body do |fragment|
        body << fragment
        thread[:done] = (thread[:done] || 0) + fragment.length
        thread[:progress] = thread[:done].quo(length) * 100
      end
    end
  end
end

thread = download 'http://caesar.acc.umu.se/mirror/ubuntu-releases/10.04/ubuntu-10.04-desktop-i386.iso'
puts "%.2f%%" % thread[:progress].to_f until thread.join 1

looks like rubyinstaller does something similar: https://github.com/oneclick/rubyinstaller/blob/master/rake/contrib/uri_ext.rb#L234 though looks like you may be able to do something like response.content_length to simplify, but anyway this seems to be a common way to do it...

Wow, I had forgotten I even wrote this. :D

I’m sure the rubyinstaller way is better; I believe I wrote this example in just a few minutes. It hasn’t been tested much at all.

Interestingly, it appears that you can use open-uri to have a "callback" as well: http://www.ruby-doc.org/stdlib-1.9.3/libdoc/open-uri/rdoc/OpenURI/OpenRead.html :progress_proc if that helps any followers. (open-uri for instance followers redirects, whereas net/http doesn't, so may be a better fit).

How to save the file on the disk?