Fixes #16890 - prevent discovery of managed hosts

app/models/host/discovered.rb

@@ -30,10 +30,6 @@ class Host::Discovered < ::Host::Base
     where(taxonomy_conditions).order("hosts.created_at DESC")
   }
 
-  before_destroy { |record|
-    record.update_attribute(:managed, false)
-  }
-
   def self.import_host facts
     raise(::Foreman::Exception.new(N_("Invalid facts, must be a Hash"))) unless facts.is_a?(Hash)
 
@@ -49,18 +45,18 @@ def self.import_host facts
     name_fact = return_first_valid_fact(Setting::Discovered.discovery_hostname_fact_array, facts)
     raise(::Foreman::Exception.new(N_("Invalid facts: hash does not contain a valid value for any of the facts in the discovery_hostname setting: %s"), Setting::Discovered.discovery_hostname_fact_array.join(', '))) unless name_fact && name_fact.present?
     hostname = normalize_string_for_hostname("#{hostname_prefix}#{name_fact}")
-    Rails.logger.warn "Hostname does not start with an alphabetical character" unless hostname.downcase.match /^[a-z]/
+    Rails.logger.warn "Hostname does not start with an alphabetical character" unless hostname.downcase.match(/^[a-z]/)
 
     # find existing or create new host record
     bootif_mac = FacterUtils::bootif_mac(facts).try(:downcase)
     hosts = ::Nic::Managed.where(:mac => bootif_mac, :primary => true)
-    if hosts.size == 0
+    if hosts.empty?
       host = Host.new(:name => hostname, :type => "Host::Discovered")
     else
       Rails.logger.warn "Multiple discovered hosts found with MAC address #{name_fact}, choosing one" if hosts.size > 1
       host = hosts.first.host
     end
-    host.type = "Host::Discovered"
+    raise ::Foreman::Exception.new("Host already exists as managed: %s", "#{host.name}/#{bootif_mac}") if host.type != "Host::Discovered"
 
     # and save (interfaces are created via puppet parser extension)
     host.save(:validate => false) if host.new_record?

test/unit/host_discovered_test.rb

@@ -121,6 +121,15 @@ class HostDiscoveredTest < ActiveSupport::TestCase
     assert_match(/Unable to detect primary interface using MAC/, exception.message)
   end
 
+  test "should not create discovered host when managed host exists" do
+    FactoryGirl.create(:host, :mac => 'E4:1F:13:CC:36:58')
+    raw = parse_json_fixture('/facts.json')
+    exception = assert_raises(::Foreman::Exception) do
+      Host::Discovered.import_host(raw['facts'])
+    end
+    assert_match(/Host already exists as managed/, exception.message)
+  end
+
   test "should create discovered host with prefix" do
     raw = parse_json_fixture('/facts.json')
     Setting[:discovery_prefix] = 'test'