Fetch expiry date and other info from certificate

get_cert_expire_info.rb

#!/usr/bin/env ruby

# frozen_string_literal: true

require "time"
require "openssl"

def get_expiry_date(host)
  ctx = OpenSSL::SSL::SSLContext.new
  sock = TCPSocket.new(host, 443)

  ssl = OpenSSL::SSL::SSLSocket.new(sock, ctx)
  ssl.hostname = host
  ssl.connect

  cert = ssl.peer_cert

  {
    hostname: host,
    expires_in_days: (cert.not_after - Time.now).to_i / (24 * 60 * 60),
    vertion: cert.version,
    not_before: cert.not_before,
    not_after: cert.not_after
  }
end

p get_expiry_date(ARGV[0])