guests/redhat: set hostname on EL7 [GH-4352]

CHANGELOG.md

@@ -71,6 +71,7 @@ BUG FIXES:
   - guests/redhat: NFS setup should use systemd for RH7+ [GH-4228]
   - guests/redhat: Detect RHEL 7 (and CentOS) and install Docker properly. [GH-4402]
   - guests/redhat: Configuring networks on EL7 works. [GH-4195]
+  - guests/redhat: Setting hostname on EL7 works. [GH-4352]
   - guests/smartos: Use `pfexec` for rsync. [GH-4274]
   - guests/windows: Reboot after hostname change. [GH-3987]
   - hosts/arch: NFS works with latest versions. [GH-4224]

plugins/guests/redhat/cap/change_host_name.rb

@@ -3,7 +3,16 @@ module GuestRedHat
     module Cap
       class ChangeHostName
         def self.change_host_name(machine, name)
-          new(machine, name).change!
+          case machine.guest.capability("flavor")
+          when :rhel_7
+            change_host_name_rhel7(machine, name)
+          else
+            new(machine, name).change!
+          end
+        end
+
+        def self.change_host_name_rhel7(machine, name)
+          machine.communicate.sudo("homenamectl set-hostname #{name}")
         end
 
         attr_reader :machine, :new_hostname

test/unit/plugins/guests/redhat/cap/change_host_name_test.rb

@@ -7,17 +7,20 @@
   end
   let(:machine) { double("machine") }
   let(:communicator) { VagrantTests::DummyCommunicator::Communicator.new(machine) }
+  let(:guest) { double("guest") }
 
   before do
+    allow(guest).to receive(:capability).and_return(nil)
     allow(machine).to receive(:communicate).and_return(communicator)
+    allow(machine).to receive(:guest).and_return(guest)
     communicator.stub_command('hostname -f', stdout: old_hostname)
     communicator.expect_command('hostname -f')
   end
 
   after do
     communicator.verify_expectations!
   end
-  
+
   context 'when oldhostname is qualified' do
     let(:old_hostname) { 'oldhostname.olddomain.tld' }
     let(:similar_hostname) {'oldhostname'}
@@ -26,7 +29,7 @@
 
     include_examples 'inserting hostname in /etc/hosts'
     include_examples 'swapping simple hostname in /etc/hosts'
-    include_examples 'swapping qualified hostname in /etc/hosts' 
+    include_examples 'swapping qualified hostname in /etc/hosts'
   end
 
   context 'when oldhostname is simple' do