Fix RemoteClient usage in scenario tests

Some scenario tests use the following patter to work with RemoteClient:

   client = self.get_remote_client(ip,
                                   private_key=keypair.private_key)
   return client.ssh_client

ssh_client is directly accessed because exec_command method
is not directly available in RemoteClient

In order to preserve encapsulation, RemoteClient should be improved to
expose that method.

Change-Id: I054762d769d002b5fb45c871d85a8ca8ff294695
Closes-Bug: #1285539

tempest/common/utils/linux/remote_client.py

@@ -43,6 +43,9 @@ class RemoteClient():
                                      ssh_timeout, pkey=pkey,
                                      channel_timeout=ssh_channel_timeout)
 
+    def exec_command(self, cmd):
+        return self.ssh_client.exec_command(cmd)
+
     def validate_authentication(self):
         """Validate ssh connection and authentication
            This method raises an Exception when the validation fails.
@@ -51,33 +54,33 @@ class RemoteClient():
 
     def hostname_equals_servername(self, expected_hostname):
         # Get host name using command "hostname"
-        actual_hostname = self.ssh_client.exec_command("hostname").rstrip()
+        actual_hostname = self.exec_command("hostname").rstrip()
         return expected_hostname == actual_hostname
 
     def get_files(self, path):
         # Return a list of comma separated files
         command = "ls -m " + path
-        return self.ssh_client.exec_command(command).rstrip('\n').split(', ')
+        return self.exec_command(command).rstrip('\n').split(', ')
 
     def get_ram_size_in_mb(self):
-        output = self.ssh_client.exec_command('free -m | grep Mem')
+        output = self.exec_command('free -m | grep Mem')
         if output:
             return output.split()[1]
 
     def get_number_of_vcpus(self):
         command = 'cat /proc/cpuinfo | grep processor | wc -l'
-        output = self.ssh_client.exec_command(command)
+        output = self.exec_command(command)
         return int(output)
 
     def get_partitions(self):
         # Return the contents of /proc/partitions
         command = 'cat /proc/partitions'
-        output = self.ssh_client.exec_command(command)
+        output = self.exec_command(command)
         return output
 
     def get_boot_time(self):
         cmd = 'cut -f1 -d. /proc/uptime'
-        boot_secs = self.ssh_client.exec_command(cmd)
+        boot_secs = self.exec_command(cmd)
         boot_time = time.time() - int(boot_secs)
         return time.localtime(boot_time)
 
@@ -85,27 +88,27 @@ class RemoteClient():
         message = re.sub("([$\\`])", "\\\\\\\\\\1", message)
         # usually to /dev/ttyS0
         cmd = 'sudo sh -c "echo \\"%s\\" >/dev/console"' % message
-        return self.ssh_client.exec_command(cmd)
+        return self.exec_command(cmd)
 
     def ping_host(self, host):
         cmd = 'ping -c1 -w1 %s' % host
-        return self.ssh_client.exec_command(cmd)
+        return self.exec_command(cmd)
 
     def get_mac_address(self):
         cmd = "/sbin/ifconfig | awk '/HWaddr/ {print $5}'"
-        return self.ssh_client.exec_command(cmd)
+        return self.exec_command(cmd)
 
     def get_ip_list(self):
         cmd = "/bin/ip address"
-        return self.ssh_client.exec_command(cmd)
+        return self.exec_command(cmd)
 
     def assign_static_ip(self, nic, addr):
         cmd = "sudo /bin/ip addr add {ip}/{mask} dev {nic}".format(
             ip=addr, mask=CONF.network.tenant_network_mask_bits,
             nic=nic
         )
-        return self.ssh_client.exec_command(cmd)
+        return self.exec_command(cmd)
 
     def turn_nic_on(self, nic):
         cmd = "sudo /bin/ip link set {nic} up".format(nic=nic)
-        return self.ssh_client.exec_command(cmd)
+        return self.exec_command(cmd)

tempest/scenario/test_snapshot_pattern.py

@@ -45,11 +45,10 @@ class TestSnapshotPattern(manager.OfficialClientTest):
 
     def _ssh_to_server(self, server_or_ip):
         try:
-            linux_client = self.get_remote_client(server_or_ip)
+            return self.get_remote_client(server_or_ip)
         except Exception:
             LOG.exception()
             self._log_console_output()
-        return linux_client.ssh_client
 
     def _write_timestamp(self, server_or_ip):
         ssh_client = self._ssh_to_server(server_or_ip)

tempest/scenario/test_stamp_pattern.py

@@ -72,8 +72,7 @@ class TestStampPattern(manager.OfficialClientTest):
         server.add_floating_ip(floating_ip)
 
     def _ssh_to_server(self, server_or_ip):
-        linux_client = self.get_remote_client(server_or_ip)
-        return linux_client.ssh_client
+        return self.get_remote_client(server_or_ip)
 
     def _create_volume_snapshot(self, volume):
         snapshot_name = data_utils.rand_name('scenario-snapshot-')

tempest/scenario/test_volume_boot_pattern.py

@@ -101,14 +101,13 @@ class TestVolumeBootPattern(manager.OfficialClientTest):
             ip = server.networks[network_name_for_ssh][0]
 
         try:
-            client = self.get_remote_client(
+            return self.get_remote_client(
                 ip,
                 private_key=keypair.private_key)
         except Exception:
             LOG.exception('ssh to server failed')
             self._log_console_output()
             raise
-        return client.ssh_client
 
     def _get_content(self, ssh_client):
         return ssh_client.exec_command('cat /tmp/text')