guests/debian: setting hostname works without 127.0.1.1 [GH-3271]

CHANGELOG.md

@@ -75,6 +75,8 @@ BUG FIXES:
   - commands/rsync-auto: Interrupt exits properly. [GH-3552]
   - commands/rsync-auto: Run properly on Windows. [GH-3547]
   - communicators/ssh: Detect if `config.ssh.shell` is invalid. [GH-3040]
+  - guests/debian: Can set hostname if hosts doesn't contain an entry
+      already for 127.0.1.1 [GH-3271]
   - guests/linux: For `read_ip_address` capability, set `LANG=en` so
       it works on international systems. [GH-3029]
   - providers/virtualbox: VirtalBox detection works properly again on

plugins/guests/debian/cap/change_host_name.rb

@@ -48,12 +48,18 @@ module VagrantPlugins
         # 127.0.0.1   localhost
         # 127.0.1.1   host.fqdn.com host.fqdn host
         def update_etc_hosts
-          ip_address = '([0-9]{1,3}\.){3}[0-9]{1,3}'
-          search     = "^(#{ip_address})\\s+#{Regexp.escape(current_hostname)}(\\s.*)?$"
-          replace    = "\\1 #{fqdn} #{short_hostname}"
-          expression = ['s', search, replace, 'g'].join('@')
+          if test("grep '#{current_hostname}' /etc/hosts")
+            # Current hostname entry is in /etc/hosts
+            ip_address = '([0-9]{1,3}\.){3}[0-9]{1,3}'
+            search     = "^(#{ip_address})\\s+#{Regexp.escape(current_hostname)}(\\s.*)?$"
+            replace    = "\\1 #{fqdn} #{short_hostname}"
+            expression = ['s', search, replace, 'g'].join('@')
 
-          sudo("sed -ri '#{expression}' /etc/hosts")
+            sudo("sed -ri '#{expression}' /etc/hosts")
+          else
+            # Current hostname entry isn't in /etc/hosts, just append it
+            sudo("echo '127.0.1.1 #{fqdn} #{short_hostname}' >>/etc/hosts")
+          end
         end
 
         def refresh_hostname_service
@@ -79,6 +85,10 @@ module VagrantPlugins
         def sudo(cmd, &block)
           machine.communicate.sudo(cmd, &block)
         end
+
+        def test(cmd)
+          machine.communicate.test(cmd)
+        end
       end
     end
   end