check-dns.rb has 2 checks, better than none.

ci/tasks/check-dns.rb

@@ -1 +1,23 @@
 #!/usr/bin/env ruby
+
+domain=ENV['DOMAIN']
+
+def check_domain(domain)
+  raise "'DOMAIN' environment variable not set!" if domain.nil?
+  raise "'DOMAIN' environment variable is empty string!" if domain == ""
+end
+
+def get_whois_nameservers(domain)
+  whois_output = `whois #{domain}`
+  whois_lines = whois_output.split(/\n+/)
+  nameserver_lines = whois_lines.select { |line| line =~ /^NS/ }
+  nameservers = nameserver_lines.map { |line| line.split.last }
+  raise "#{domain}'s whois entry has no name servers" unless nameservers.length > 0
+  nameservers
+end
+
+check_domain(domain)
+puts "[PASS] #{domain} basic check ('DOMAIN' variable set & not empty)"
+
+whois_nameservers = get_whois_nameservers(domain)
+puts "[PASS] #{domain} has whois entry with nameservers"