VM Plugin: make --vm-hostname optional by attempting to find IP address

By leveraging the `avocado.core.virt.VM.ip_address` method, let's make
the `--vm-hostname` optional. If the IP address can not be found, then
ask users to manually provide it.

If the user has a VM running, or has had it running a "while" back,
chances are pretty high Avocado will be able to find it's IP address.
Signed-off-by: NCleber Rosa <crosa@redhat.com>

avocado/core/plugins/vm.py

@@ -47,8 +47,10 @@ class RunVM(plugin.Plugin):
                                     help=('Specify hypervisor URI driver '
                                           'connection. Current: %s' %
                                           default_hypervisor_uri))
-        self.vm_parser.add_argument('--vm-hostname',
-                                    help='Specify VM hostname to login')
+        self.vm_parser.add_argument('--vm-hostname', default=None,
+                                    help=('Specify VM hostname to login. By '
+                                          'default it attempts to automatically'
+                                          ' find the VM IP address.'))
         self.vm_parser.add_argument('--vm-username', default=username,
                                     help='Specify the username to login on VM')
         self.vm_parser.add_argument('--vm-password',
@@ -89,7 +91,6 @@ class RunVM(plugin.Plugin):
         return True
 
     def activate(self, app_args):
-        if self._check_required_args(app_args, 'vm_domain',
-                                     ('vm_domain', 'vm_hostname')):
+        if self._check_required_args(app_args, 'vm_domain', ('vm_domain',)):
             self.vm_parser.set_defaults(remote_result=VMTestResult,
                                         test_runner=RemoteTestRunner)

avocado/core/remote/result.py

@@ -106,11 +106,6 @@ class VMTestResult(RemoteTestResult):
 
     def setup(self):
         # Super called after VM is found and initialized
-        if self.args.vm_hostname is None:
-            e_msg = ('Please set Virtual Machine hostname with option '
-                     '--vm-hostname.')
-            self.stream.notify(event='error', msg=e_msg)
-            raise exceptions.JobError(e_msg)
         self.stream.notify(event='message', msg="DOMAIN     : %s"
                            % self.args.vm_domain)
         self.vm = virt.vm_connect(self.args.vm_domain,
@@ -122,6 +117,14 @@ class VMTestResult(RemoteTestResult):
             e_msg = "Could not start VM '%s'" % self.args.vm_domain
             raise exceptions.JobError(e_msg)
         assert self.vm.domain.isActive() is not False
+        # If hostname wasn't given, let's try to find out the IP address
+        if self.args.vm_hostname is None:
+            self.args.vm_hostname = self.vm.ip_address()
+            if self.args.vm_hostname is None:
+                e_msg = ("Could not find the IP address for VM '%s'. Please "
+                         "set it explicitly with --vm-hostname" %
+                         self.args.vm_domain)
+                raise exceptions.JobError(e_msg)
         if self.args.vm_cleanup is True:
             self.vm.create_snapshot()
             if self.vm.snapshot is None:

docs/source/RunningTestsRemotely.rst

@@ -96,7 +96,8 @@ when using the ``run`` command in the Avocado command line tool::
       --vm-domain VM_DOMAIN
                             Specify domain name (Virtual Machine name)
       --vm-hostname VM_HOSTNAME
-                            Specify VM hostname to login
+                            Specify VM hostname to login. By default it attempts
+                            to automatically find the VM IP address.
       --vm-username VM_USERNAME
                             Specify the username to login on VM
       --vm-password VM_PASSWORD
@@ -108,6 +109,11 @@ From these options, you are normally going to use `--vm-domain`,
 `--vm-hostname` and `--vm-username` in case you did set up your VM with
 password-less SSH connection (through SSH keys).
 
+If you have the VM already running, or have had it running and it a
+"while" back, you can probably skip the `--vm-hostname` option as
+Avocado will attempt to find out the VM IP address based on the MAC
+address and ARP table.
+
 Virtual Machine Setup
 ---------------------