Making HEAD request in Ruby - ruby

Question

I am kind of new to ruby and from a python background
I want to make a head request to a URL and check some information like if the file exists on the server and timestamp, etag etc.,I am not able to get this done in RUBY.
In Python:
import httplib2
print httplib2.Http().request('url.com/file.xml','HEAD')
In Ruby: I tried this and throwing some error
require 'net/http'
Net::HTTP.start('url.com'){|http|
response = http.head('/file.xml')
}
puts response
SocketError: getaddrinfo: nodename nor servname provided, or not known
from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:877:in `initialize'
from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:877:in `open'
from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:877:in `block in connect'
from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/timeout.rb:51:in `timeout'
from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:876:in `connect'
from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:861:in `do_start'
from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:850:in `start'
from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/lib/ruby/2.0.0/net/http.rb:582:in `start'
from (irb):2
from /Users/comcast/.rvm/rubies/ruby-2.0.0-p0/bin/irb:16:in `<main>'

Answer 1

I realize this has been answered but I had to go through some hoops, too. Here's something more concrete to start with:
#!/usr/bin/env ruby
require 'net/http'
require 'net/https' # for openssl
uri = URI('http://stackoverflow.com')
path = '/questions/16325918/making-head-request-in-ruby'
response=nil
http = Net::HTTP.new(uri.host, uri.port)
# http.use_ssl = true # if using SSL
# http.verify_mode = OpenSSL::SSL::VERIFY_NONE # for example, when using self-signed certs
response = http.head(path)
response.each { |key, value| puts key.ljust(40) + " : " + value }

Answer 2

I don't think that passing in a string to :start is enough; in the docs it looks like it requires a URI object's host and port for a correct address:
uri = URI('http://example.com/some_path?query=string')
Net::HTTP.start(uri.host, uri.port) do |http|
request = Net::HTTP::Get.new uri
response = http.request request # Net::HTTPResponse object
end
You can try this:
require 'net/http'
url = URI('yoururl.com')
Net::HTTP.start(url.host, url.port){|http|
response = http.head('/file.xml')
puts response
}
One thing I noticed - your puts response needs to be inside the block! Otherwise, the variable response is not in scope.
Edit: You can also treat the response as a hash to get the values of the headers:
response.each_value { |value| puts value }

Answer 3

headers = nil
url = URI('http://my-bucket.amazonaws.com/filename.mp4')
Net::HTTP.start(url.host, url.port) do |http|
headers = http.head(url.path).to_hash
end
And now you have a hash of headers in headers