Fix pylint warnings in python libraries

 - no functional changes
 - fixes 80+ PEP-8 violations

Change-Id: Icf414778ec40d5cb44364fa69a876f9a1870c3c7
Signed-off-by: selias <samelias@cisco.com>

16 files changed, 206 insertions, 89 deletions

diff --git a/resources/libraries/python/Classify.py b/resources/libraries/python/Classify.py
index 8dbe3fb25f..c781bbbd14 100644
--- a/resources/libraries/python/Classify.py
+++ b/resources/libraries/python/Classify.py
@@ -11,12 +11,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+"""Classify utilities library."""
 
 from robot.api import logger
 
 from resources.libraries.python.VatExecutor import VatExecutor, VatTerminal
 
 
+# pylint: disable=too-many-arguments, invalid-name
+
 class Classify(object):
     """Classify utilities."""
 
@@ -117,9 +120,9 @@ class Classify(object):
         return table_index, skip_n, match_n
 
     @staticmethod
-    def vpp_configures_classify_session_l3(node, acl_method, table_index, skip_n,
-                                          match_n, ip_version, direction,
-                                          address):
+    def vpp_configures_classify_session_l3(node, acl_method, table_index,
+                                           skip_n, match_n, ip_version,
+                                           direction, address):
         """Configuration of classify session for IP address filtering.
 
         :param node: VPP node to setup classify session.
@@ -150,8 +153,8 @@ class Classify(object):
                                                     address=address)
 
     @staticmethod
-    def vpp_configures_classify_session_l2(node, acl_method, table_index, skip_n,
-                                          match_n, direction, address):
+    def vpp_configures_classify_session_l2(node, acl_method, table_index,
+                                           skip_n, match_n, direction, address):
         """Configuration of classify session for MAC address filtering.
 
         :param node: VPP node to setup classify session.
@@ -170,17 +173,18 @@ class Classify(object):
         :type address: str
         """
         with VatTerminal(node) as vat:
-            vat.vat_terminal_exec_cmd_from_template("classify_add_session_l2.vat",
-                                                    acl_method=acl_method,
-                                                    table_index=table_index,
-                                                    skip_n=skip_n,
-                                                    match_n=match_n,
-                                                    direction=direction,
-                                                    address=address)
+            vat.vat_terminal_exec_cmd_from_template(
+                "classify_add_session_l2.vat",
+                acl_method=acl_method,
+                table_index=table_index,
+                skip_n=skip_n,
+                match_n=match_n,
+                direction=direction,
+                address=address)
 
     @staticmethod
     def vpp_configures_classify_session_hex(node, acl_method, table_index,
-                                           skip_n, match_n, hex_value):
+                                            skip_n, match_n, hex_value):
         """Configuration of classify session with hex value.
 
         :param node: VPP node to setup classify session.
diff --git a/resources/libraries/python/DUTSetup.py b/resources/libraries/python/DUTSetup.py
index e2d183fe4e..e176dd704a 100644
--- a/resources/libraries/python/DUTSetup.py
+++ b/resources/libraries/python/DUTSetup.py
@@ -11,6 +11,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+"""DUT setup library."""
+
 from robot.api import logger
 
 from resources.libraries.python.topology import NodeType
@@ -20,6 +22,7 @@ from resources.libraries.python.VatExecutor import VatExecutor
 
 
 class DUTSetup(object):
+    """Contains methods for setting up DUTs."""
     @staticmethod
     def start_vpp_service_on_all_duts(nodes):
         """Start up the VPP service on all nodes."""
@@ -29,7 +32,7 @@ class DUTSetup(object):
                 ssh.connect(node)
                 (ret_code, stdout, stderr) = \
                     ssh.exec_command_sudo('service vpp restart')
-                if 0 != int(ret_code):
+                if int(ret_code) != 0:
                     logger.debug('stdout: {0}'.format(stdout))
                     logger.debug('stderr: {0}'.format(stderr))
                     raise Exception('DUT {0} failed to start VPP service'.
@@ -74,6 +77,13 @@ class DUTSetup(object):
 
     @staticmethod
     def setup_dut(node):
+        """Run script over SSH to setup the DUT node.
+
+        :param node: DUT node to set up.
+        :type node: dict
+
+        :raises Exception: If the DUT setup fails.
+        """
         ssh = SSH()
         ssh.connect(node)
 
@@ -82,7 +92,7 @@ class DUTSetup(object):
                 Constants.REMOTE_FW_DIR, Constants.RESOURCES_LIB_SH))
         logger.trace(stdout)
         logger.trace(stderr)
-        if 0 != int(ret_code):
+        if int(ret_code) != 0:
             logger.debug('DUT {0} setup script failed: "{1}"'.
                          format(node['host'], stdout + stderr))
             raise Exception('DUT test setup script failed at node {}'.
diff --git a/resources/libraries/python/IPv4Setup.py b/resources/libraries/python/IPv4Setup.py
index d4be4c602a..07089025b0 100644
--- a/resources/libraries/python/IPv4Setup.py
+++ b/resources/libraries/python/IPv4Setup.py
@@ -34,6 +34,15 @@ class IPv4Node(object):
 
     @staticmethod
     def _get_netmask(prefix_length):
+        """Convert IPv4 network prefix length into IPV4 network mask.
+
+        :param prefix_length: Length of network prefix.
+        :type prefix_length: int
+
+        :return: Network mask.
+        :rtype: str
+        """
+
         bits = 0xffffffff ^ (1 << 32 - prefix_length) - 1
         return inet_ntoa(pack('>I', bits))
 
@@ -112,9 +121,25 @@ class Tg(IPv4Node):
         super(Tg, self).__init__(node_info)
 
     def _execute(self, cmd):
+        """Executes the specified command on TG using SSH.
+
+        :param cmd: Command to be executed.
+        :type cmd: str
+
+        :return: Content of stdout and stderr returned by command.
+        :rtype: tuple
+        """
         return exec_cmd_no_error(self.node_info, cmd)
 
     def _sudo_execute(self, cmd):
+        """Executes the specified command with sudo on TG using SSH.
+
+        :param cmd: Command to be executed.
+        :type cmd: str
+
+        :return: Content of stdout and stderr returned by command.
+        :rtype: tuple
+        """
         return exec_cmd_no_error(self.node_info, cmd, sudo=True)
 
     def set_ip(self, interface, address, prefix_length):
@@ -135,6 +160,13 @@ class Tg(IPv4Node):
                            format(network, prefix_length))
 
     def arp_ping(self, destination_address, source_interface):
+        """Execute 'arping' command to send one ARP packet from the TG node.
+
+        :param destination_address: Destination IP address for the ARP packet.
+        :param source_interface: Name of an interface to send ARP packet from.
+        :type destination_address: str
+        :type source_interface: str
+        """
         self._sudo_execute('arping -c 1 -I {} {}'.format(source_interface,
                                                          destination_address))
 
@@ -207,6 +239,7 @@ class Dut(IPv4Node):
                       sw_if_index=self.get_sw_if_index(interface))
 
     def arp_ping(self, destination_address, source_interface):
+        """Does nothing."""
         pass
 
     def flush_ip_addresses(self, interface):
@@ -286,9 +319,9 @@ class IPv4Setup(object):
                 host = port.get('node')
                 dev = port.get('if')
                 if host == node['host'] and dev == interface:
-                    ip = port.get('addr')
-                    if ip is not None:
-                        return ip
+                    ip_addr = port.get('addr')
+                    if ip_addr is not None:
+                        return ip_addr
                     else:
                         raise Exception(
                             'Node {n} port {p} IPv4 address is not set'.format(
diff --git a/resources/libraries/python/IPv4Util.py b/resources/libraries/python/IPv4Util.py
index ca5a1b571f..96572f5e1d 100644
--- a/resources/libraries/python/IPv4Util.py
+++ b/resources/libraries/python/IPv4Util.py
@@ -28,6 +28,15 @@ class IPv4Util(object):
     @keyword('From node "${node}" interface "${port}" ARP-ping '
              'IPv4 address "${ip_address}"')
     def arp_ping(node, interface, ip_address):
+        """Send an ARP ping from the specified node.
+
+        :param node: Node in topology.
+        :param ip_address: Destination IP address for the ARP packet.
+        :param interface: Name of an interface to send the ARP packet from.
+        :type node: dict
+        :type ip_address: str
+        :type interface: str
+        """
         log.debug('From node {} interface {} ARP-ping IPv4 address {}'.
                   format(Topology.get_node_hostname(node),
                          interface, ip_address))
@@ -89,8 +98,8 @@ class IPv4Util(object):
         :rtype: int
         """
         for net in nodes_addr.values():
-            for p in net['ports'].values():
-                if p['node'] == node['host'] and p['if'] == port:
+            for net_port in net['ports'].values():
+                if net_port['node'] == node['host'] and net_port['if'] == port:
                     return net['prefix']
 
         raise Exception('Subnet not found for node {n} port {p}'.
@@ -112,8 +121,8 @@ class IPv4Util(object):
         :rtype: str
         """
         for net in nodes_addr.values():
-            for p in net['ports'].values():
-                if p['node'] == node['host'] and p['if'] == port:
+            for net_port in net['ports'].values():
+                if net_port['node'] == node['host'] and net_port['if'] == port:
                     return net['net_addr']
 
         raise Exception('Subnet not found for node {n} port {p}'.
@@ -189,32 +198,32 @@ class IPv4Util(object):
                 interface, ping_count, destination)
         else:
             cmd = 'ping -c{0} {1}'.format(ping_count, destination)
-        rc, stdout, stderr = exec_cmd(node, cmd, sudo=True)
-        if rc != 0:
+        ret_code, _, _ = exec_cmd(node, cmd, sudo=True)
+        if ret_code != 0:
             raise RuntimeError("Ping Not Successful")
 
     @staticmethod
-    def set_linux_interface_arp(node, interface, ip, mac, namespace=None):
+    def set_linux_interface_arp(node, interface, ip_addr, mac, namespace=None):
         """Set arp on interface in linux.
 
         :param node: Node where to execute command.
         :param interface: Interface in namespace.
-        :param ip: IP for arp.
+        :param ip_addr: IP address for ARP entry.
         :param mac: MAC address.
         :param namespace: Execute command in namespace. Optional
         :type node: dict
         :type interface: str
-        :type ip: str
+        :type ip_addr: str
         :type mac: str
         :type namespace: str
         :raises RuntimeError: Could not set ARP properly.
         """
         if namespace is not None:
             cmd = 'ip netns exec {} arp -i {} -s {} {}'.format(
-                namespace, interface, ip, mac)
+                namespace, interface, ip_addr, mac)
         else:
-            cmd = 'arp -i {} -s {} {}'.format(interface, ip, mac)
-        rc, _, stderr = exec_cmd(node, cmd, sudo=True)
-        if rc != 0:
+            cmd = 'arp -i {} -s {} {}'.format(interface, ip_addr, mac)
+        ret_code, _, stderr = exec_cmd(node, cmd, sudo=True)
+        if ret_code != 0:
             raise RuntimeError("Arp set not successful, reason:{}".
                                format(stderr))
diff --git a/resources/libraries/python/IPv6Util.py b/resources/libraries/python/IPv6Util.py
index 54196ebf52..2a4704dff2 100644
--- a/resources/libraries/python/IPv6Util.py
+++ b/resources/libraries/python/IPv6Util.py
@@ -46,7 +46,7 @@ class IPv6Util(object):
         cmd = "ping6 -c {c} -s {s} -W {W} {dst}".format(c=count, s=data_size,
                                                         W=timeout,
                                                         dst=dst_addr)
-        (ret_code, stdout, _) = ssh.exec_command(cmd)
+        (_, stdout, _) = ssh.exec_command(cmd)
 
         regex = re.compile(r'(\d+) packets transmitted, (\d+) received')
         match = regex.search(stdout)
@@ -99,9 +99,9 @@ class IPv6Util(object):
                 host = port.get('node')
                 dev = port.get('if')
                 if host == node['host'] and dev == interface:
-                    ip = port.get('addr')
-                    if ip is not None:
-                        return ip
+                    ip_addr = port.get('addr')
+                    if ip_addr is not None:
+                        return ip_addr
                     else:
                         raise Exception(
                             'Node {n} port {p} IPv6 address is not set'.format(
diff --git a/resources/libraries/python/LispSetup.py b/resources/libraries/python/LispSetup.py
index ee2ae5d8a3..99e3de8f74 100644
--- a/resources/libraries/python/LispSetup.py
+++ b/resources/libraries/python/LispSetup.py
@@ -103,6 +103,8 @@ class LispRemoteMapping(object):
                                       seid=seid,
                                       seid_prefix=seid_prefix,
                                       rloc=rloc)
+
+
 class LispAdjacency(object):
     """Class for lisp adjacency API."""
 
@@ -117,7 +119,7 @@ class LispAdjacency(object):
         :param node: VPP node.
         :param vni: Vni.
         :param deid: Destination eid address.
-        :param deid_predix: Destination eid address prefix_len.
+        :param deid_prefix: Destination eid address prefix_len.
         :param seid: Source eid address.
         :param seid_prefix: Source eid address prefix_len.
         :type node: dict
@@ -144,7 +146,7 @@ class LispAdjacency(object):
         :param node: VPP node.
         :param vni: Vni.
         :param deid: Destination eid address.
-        :param deid_predix: Destination eid address prefix_len.
+        :param deid_prefix: Destination eid address prefix_len.
         :param seid: Source eid address.
         :param seid_prefix: Source eid address prefix_len.
         :type node: dict
@@ -216,11 +218,13 @@ class LispGpeForwardEntry(object):
 
     @staticmethod
     def add_lisp_gpe_forward_entry(node, *args):
+        """Not implemented"""
         # TODO: Implement when VPP-334 is fixed.
         pass
 
     @staticmethod
     def del_lisp_gpe_forward_entry(node, *args):
+        """Not implemented"""
         # TODO: Implement when VPP-334 is fixed.
         pass
 
diff --git a/resources/libraries/python/Namespaces.py b/resources/libraries/python/Namespaces.py
index d92dfd7e26..00d615350e 100644
--- a/resources/libraries/python/Namespaces.py
+++ b/resources/libraries/python/Namespaces.py
@@ -13,7 +13,7 @@
 
 """Linux namespace utilities library."""
 
-from resources.libraries.python.ssh import exec_cmd_no_error, exec_cmd, SSH
+from resources.libraries.python.ssh import exec_cmd_no_error, exec_cmd
 
 
 class Namespaces(object):
@@ -46,14 +46,14 @@ class Namespaces(object):
         :raises RuntimeError: Interface could not be attached.
         """
         cmd = 'ip link set {0} netns {1}'.format(interface, namespace)
-        (rc, _, stderr) = exec_cmd(node, cmd, timeout=5, sudo=True)
-        if rc != 0:
+        (ret_code, _, stderr) = exec_cmd(node, cmd, timeout=5, sudo=True)
+        if ret_code != 0:
             raise RuntimeError(
                 'Could not attach interface, reason:{}'.format(stderr))
         cmd = 'ip netns exec {} ip link set {} up'.format(
             namespace, interface)
-        (rc, _, stderr) = exec_cmd(node, cmd, timeout=5, sudo=True)
-        if rc != 0:
+        (ret_code, _, stderr) = exec_cmd(node, cmd, timeout=5, sudo=True)
+        if ret_code != 0:
             raise RuntimeError(
                 'Could not set interface state, reason:{}'.format(stderr))
 
@@ -91,6 +91,6 @@ class Namespaces(object):
         for namespace in self._namespaces:
             print "Cleaning namespace {}".format(namespace)
             cmd = 'ip netns delete {}'.format(namespace)
-            (rc, stdout, stderr) = exec_cmd(node, cmd, timeout=5, sudo=True)
-            if rc != 0:
+            (ret_code, _, _) = exec_cmd(node, cmd, timeout=5, sudo=True)
+            if ret_code != 0:
                 raise RuntimeError('Could not delete namespace')
diff --git a/resources/libraries/python/PacketVerifier.py b/resources/libraries/python/PacketVerifier.py
index 59ea2db5a3..bbfdfe8688 100644
--- a/resources/libraries/python/PacketVerifier.py
+++ b/resources/libraries/python/PacketVerifier.py
@@ -68,7 +68,7 @@ import socket
 import select
 
 from scapy.all import ETH_P_IP, ETH_P_IPV6, ETH_P_ALL, ETH_P_ARP
-from scapy.all import Ether, ARP, Packet
+from scapy.all import Ether, ARP
 from scapy.layers.inet6 import IPv6
 
 __all__ = ['RxQueue', 'TxQueue', 'Interface', 'create_gratuitous_arp_request',
@@ -276,17 +276,32 @@ class TxQueue(PacketVerifier):
 
 
 class Interface(object):
+    """Class for network interfaces. Contains methods for sending and receiving
+     packets."""
     def __init__(self, if_name):
+        """Initialize the interface class.
+
+        :param if_name: Name of the interface.
+        :type if_name: str
+        """
         self.if_name = if_name
         self.sent_packets = []
         self.rxq = RxQueue(if_name)
         self.txq = TxQueue(if_name)
 
     def send_pkt(self, pkt):
+        """Send the provided packet out the interface."""
         self.sent_packets.append(pkt)
         self.txq.send(pkt)
 
     def recv_pkt(self, timeout=3):
+        """Read one packet from the interface's receive queue.
+
+        :param timeout: Timeout value in seconds.
+        :type timeout: int
+        :return: Ether() initialized object from packet data.
+        :rtype: scapy.Ether
+        """
         return self.rxq.recv(timeout, self.sent_packets)
 
 
diff --git a/resources/libraries/python/QemuUtils.py b/resources/libraries/python/QemuUtils.py
index bc854350dd..aa149da185 100644
--- a/resources/libraries/python/QemuUtils.py
+++ b/resources/libraries/python/QemuUtils.py
@@ -215,10 +215,10 @@ class QemuUtils(object):
             '{ \\"execute\\": \\"' + cmd + '\\" }" | sudo -S nc -U ' + \
             self.__QMP_SOCK
         (ret_code, stdout, stderr) = self._ssh.exec_command(qmp_cmd)
-        if 0 != int(ret_code):
+        if int(ret_code) != 0:
             logger.debug('QMP execute failed {0}'.format(stderr))
-            raise RuntimeError('QMP execute "{0}" failed on {1}'.format(cmd,
-                self._node['host']))
+            raise RuntimeError('QMP execute "{0}"'
+                               ' failed on {1}'.format(cmd, self._node['host']))
         logger.trace(stdout)
         # Skip capabilities negotiation messages.
         out_list = stdout.splitlines()
@@ -233,10 +233,10 @@ class QemuUtils(object):
         qga_cmd = 'printf "\xFF" | sudo -S nc ' \
             '-q 1 -U ' + self.__QGA_SOCK
         (ret_code, stdout, stderr) = self._ssh.exec_command(qga_cmd)
-        if 0 != int(ret_code):
+        if int(ret_code) != 0:
             logger.debug('QGA execute failed {0}'.format(stderr))
-            raise RuntimeError('QGA execute "{0}" failed on {1}'.format(cmd,
-                self._node['host']))
+            raise RuntimeError('QGA execute "{0}" '
+                               'failed on {1}'.format(cmd, self._node['host']))
         logger.trace(stdout)
         if not stdout:
             return {}
@@ -253,10 +253,10 @@ class QemuUtils(object):
         qga_cmd = 'echo "{ \\"execute\\": \\"' + cmd + '\\" }" | sudo -S nc ' \
             '-q 1 -U ' + self.__QGA_SOCK
         (ret_code, stdout, stderr) = self._ssh.exec_command(qga_cmd)
-        if 0 != int(ret_code):
+        if int(ret_code) != 0:
             logger.debug('QGA execute failed {0}'.format(stderr))
-            raise RuntimeError('QGA execute "{0}" failed on {1}'.format(cmd,
-                self._node['host']))
+            raise RuntimeError('QGA execute "{0}"'
+                               ' failed on {1}'.format(cmd, self._node['host']))
         logger.trace(stdout)
         if not stdout:
             return {}
@@ -353,8 +353,10 @@ class QemuUtils(object):
                         self._node['host']))
             # If we do not want to allocate dynamicaly end with error
             else:
-                raise RuntimeError('Not enough free huge pages: {0}, '
-                    '{1} MB'.format(huge_free, huge_free * huge_size))
+                raise RuntimeError(
+                    'Not enough free huge pages: {0}, '
+                    '{1} MB'.format(huge_free, huge_free * huge_size)
+                )
         # Check if huge pages mount point exist
         has_huge_mnt = False
         (_, output, _) = self._ssh.exec_command('cat /proc/mounts')
@@ -395,7 +397,7 @@ class QemuUtils(object):
         # Memory and huge pages
         mem = '-object memory-backend-file,id=mem,size={0}M,mem-path={1},' \
             'share=on -m {0} -numa node,memdev=mem'.format(
-            self._qemu_opt.get('mem_size'), self._qemu_opt.get('huge_mnt'))
+                self._qemu_opt.get('mem_size'), self._qemu_opt.get('huge_mnt'))
 
         # By default check only if hugepages are availbale.
         # If 'huge_allocate' is set to true try to allocate as well.
@@ -406,7 +408,7 @@ class QemuUtils(object):
         # Setup serial console
         serial = '-chardev socket,host=127.0.0.1,port={0},id=gnc0,server,' \
             'nowait -device isa-serial,chardev=gnc0'.format(
-            self._qemu_opt.get('serial_port'))
+                self._qemu_opt.get('serial_port'))
         # Setup QGA via chardev (unix socket) and isa-serial channel
         qga = '-chardev socket,path=/tmp/qga.sock,server,nowait,id=qga0 ' \
             '-device isa-serial,chardev=qga0'
@@ -443,15 +445,18 @@ class QemuUtils(object):
         out = self._qemu_qmp_exec('system_powerdown')
         err = out.get('error')
         if err is not None:
-            raise RuntimeError('QEMU system powerdown failed on {0}, '
-                'error: {1}'.format(self._node['host'], json.dumps(err)))
+            raise RuntimeError(
+                'QEMU system powerdown failed on {0}, '
+                'error: {1}'.format(self._node['host'], json.dumps(err))
+            )
 
     def qemu_system_reset(self):
         """Reset the system."""
         out = self._qemu_qmp_exec('system_reset')
         err = out.get('error')
         if err is not None:
-            raise RuntimeError('QEMU system reset failed on {0}, '
+            raise RuntimeError(
+                'QEMU system reset failed on {0}, '
                 'error: {1}'.format(self._node['host'], json.dumps(err)))
 
     def qemu_kill(self):
@@ -501,7 +506,8 @@ class QemuUtils(object):
             return ret.get('status')
         else:
             err = out.get('error')
-            raise RuntimeError('QEMU query-status failed on {0}, '
+            raise RuntimeError(
+                'QEMU query-status failed on {0}, '
                 'error: {1}'.format(self._node['host'], json.dumps(err)))
 
     @staticmethod
@@ -518,6 +524,6 @@ class QemuUtils(object):
             ssh.exec_command('sudo -Sn bash {0}/{1}/qemu_build.sh'.format(
                 Constants.REMOTE_FW_DIR, Constants.RESOURCES_LIB_SH), 1000)
         logger.trace(stdout)
-        if 0 != int(ret_code):
+        if int(ret_code) != 0:
             logger.debug('QEMU build failed {0}'.format(stderr))
             raise RuntimeError('QEMU build failed on {0}'.format(node['host']))
diff --git a/resources/libraries/python/Routing.py b/resources/libraries/python/Routing.py
index fbe7b60183..ff675f39a9 100644
--- a/resources/libraries/python/Routing.py
+++ b/resources/libraries/python/Routing.py
@@ -17,10 +17,12 @@ from resources.libraries.python.VatExecutor import VatTerminal
 from resources.libraries.python.topology import Topology
 from resources.libraries.python.ssh import exec_cmd_no_error
 
+
 class Routing(object):
 
     """Routing utilities."""
 
+    # pylint: disable=too-many-arguments
     @staticmethod
     def vpp_route_add(node, network, prefix_len, gateway=None,
                       interface=None, use_sw_index=True, resolve_attempts=10,
@@ -101,23 +103,23 @@ class Routing(object):
                                                     where=place)
 
     @staticmethod
-    def add_route(node, ip, prefix, gw, namespace=None):
+    def add_route(node, ip_addr, prefix, gateway, namespace=None):
         """Add route in namespace.
 
         :param node: Node where to execute command.
-        :param ip: Route destination IP.
+        :param ip_addr: Route destination IP address.
         :param prefix: IP prefix.
-        :param namespace: Execute command in namespace. Optional
-        :param gw: Gateway.
+        :param namespace: Execute command in namespace. Optional.
+        :param gateway: Gateway address.
         :type node: dict
-        :type ip: str
+        :type ip_addr: str
         :type prefix: int
-        :type gw: str
+        :type gateway: str
         :type namespace: str
         """
         if namespace is not None:
             cmd = 'ip netns exec {} ip route add {}/{} via {}'.format(
-                namespace, ip, prefix, gw)
+                namespace, ip_addr, prefix, gateway)
         else:
-            cmd = 'ip route add {}/{} via {}'.format(ip, prefix, gw)
+            cmd = 'ip route add {}/{} via {}'.format(ip_addr, prefix, gateway)
         exec_cmd_no_error(node, cmd, sudo=True)
diff --git a/resources/libraries/python/SetupFramework.py b/resources/libraries/python/SetupFramework.py
index 1a1e991b3b..d0059ebed8 100644
--- a/resources/libraries/python/SetupFramework.py
+++ b/resources/libraries/python/SetupFramework.py
@@ -58,7 +58,7 @@ def pack_framework_dir():
     logger.debug(stderr)
 
     return_code = proc.wait()
-    if 0 != return_code:
+    if return_code != 0:
         raise Exception("Could not pack testing framework.")
 
     return file_name
@@ -99,7 +99,7 @@ def extract_tarball_at_node(tarball, node):
     cmd = 'sudo rm -rf {1}; mkdir {1} ; tar -zxf {0} -C {1}; ' \
         'rm -f {0}'.format(tarball, con.REMOTE_FW_DIR)
     (ret_code, _, stderr) = ssh.exec_command(cmd, timeout=30)
-    if 0 != ret_code:
+    if ret_code != 0:
         logger.error('Unpack error: {0}'.format(stderr))
         raise Exception('Failed to unpack {0} at node {1}'.format(
             tarball, node['host']))
@@ -116,7 +116,7 @@ def create_env_directory_at_node(node):
         '. env/bin/activate && '
         'pip install -r requirements.txt'
         .format(con.REMOTE_FW_DIR), timeout=100)
-    if 0 != ret_code:
+    if ret_code != 0:
         logger.error('Virtualenv creation error: {0}'.format(stdout + stderr))
         raise Exception('Virtualenv setup failed')
     else:
diff --git a/resources/libraries/python/VatExecutor.py b/resources/libraries/python/VatExecutor.py
index a0f9634d8c..03b7321020 100644
--- a/resources/libraries/python/VatExecutor.py
+++ b/resources/libraries/python/VatExecutor.py
@@ -11,6 +11,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+"""VAT executor library."""
+
 import json
 
 from robot.api import logger
@@ -39,6 +41,7 @@ def cleanup_vat_json_output(json_output):
 
 
 class VatExecutor(object):
+    """Contains methods for executing VAT commands on DUTs."""
     def __init__(self):
         self._stdout = None
         self._stderr = None
@@ -62,7 +65,7 @@ class VatExecutor(object):
                                                 Constants.RESOURCES_TPL_VAT,
                                                 vat_name)
         # TODO this overwrites the output if the vat script has been used twice
-        remote_file_out = remote_file_path + ".out"
+        # remote_file_out = remote_file_path + ".out"
 
         cmd = "sudo -S {vat} {json} < {input}".format(
             vat=Constants.VAT_BIN_NAME,
@@ -81,17 +84,29 @@ class VatExecutor(object):
         # self._delete_files(node, remote_file_path, remote_file_out)
 
     def execute_script_json_out(self, vat_name, node, timeout=10):
+        """Pass all arguments to 'execute_script' method, then cleanup returned
+        json output."""
         self.execute_script(vat_name, node, timeout, json_out=True)
         self._stdout = cleanup_vat_json_output(self._stdout)
 
     @staticmethod
     def _delete_files(node, *files):
+        """Use SSH to delete the specified files on node.
+
+        :param node: Node in topology.
+        :param files: Files to delete.
+        :type node: dict
+        :type files: iterable
+        """
+
         ssh = SSH()
         ssh.connect(node)
         files = " ".join([str(x) for x in files])
         ssh.exec_command("rm {0}".format(files))
 
     def script_should_have_failed(self):
+        """Read return code from last executed script and raise exception if the
+        script didn't fail."""
         if self._ret_code is None:
             raise Exception("First execute the script!")
         if self._ret_code == 0:
@@ -99,6 +114,8 @@ class VatExecutor(object):
                 "Script execution passed, but failure was expected")
 
     def script_should_have_passed(self):
+        """Read return code from last executed script and raise exception if the
+        script failed."""
         if self._ret_code is None:
             raise Exception("First execute the script!")
         if self._ret_code != 0:
@@ -106,9 +123,11 @@ class VatExecutor(object):
                 "Script execution failed, but success was expected")
 
     def get_script_stdout(self):
+        """Returns value of stdout from last executed script."""
         return self._stdout
 
     def get_script_stderr(self):
+        """Returns value of stderr from last executed script."""
         return self._stderr
 
     @staticmethod
diff --git a/resources/libraries/python/VatJsonUtil.py b/resources/libraries/python/VatJsonUtil.py
index 1cafff0d27..6445d8c387 100644
--- a/resources/libraries/python/VatJsonUtil.py
+++ b/resources/libraries/python/VatJsonUtil.py
@@ -173,7 +173,7 @@ class VatJsonUtil(object):
         :type err_msg: str
         :raises RuntimeError: If VAT command return value is incorrect.
         """
-        if type(vat_out) is dict:
+        if isinstance(vat_out, dict):
             retval = vat_out.get('retval')
             if retval is not None:
                 if retval != exp_retval:
diff --git a/resources/libraries/python/ssh.py b/resources/libraries/python/ssh.py
index b470e86ccc..287ad31d65 100644
--- a/resources/libraries/python/ssh.py
+++ b/resources/libraries/python/ssh.py
@@ -11,6 +11,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+"""Library for SSH connection management."""
+
 import StringIO
 from time import time, sleep
 
@@ -19,7 +21,7 @@ import paramiko
 from paramiko import RSAKey
 from paramiko.ssh_exception import SSHException
 from scp import SCPClient
-from interruptingcow import timeout
+from interruptingcow import timeout as icTimeout
 from robot.api import logger
 from robot.utils.asserts import assert_equal
 
@@ -29,6 +31,7 @@ __all__ = ["exec_cmd", "exec_cmd_no_error"]
 
 
 class SSH(object):
+    """Contains methods for managing and using SSH connections."""
 
     __MAX_RECV_BUF = 10*1024*1024
     __existing_connections = {}
@@ -39,6 +42,14 @@ class SSH(object):
 
     @staticmethod
     def _node_hash(node):
+        """Get IP address and port hash from node dictionary.
+
+        :param node: Node in topology.
+        :type node: dict
+        :return: IP address and port for the specified node.
+        :rtype: int
+        """
+
         return hash(frozenset([node['host'], node['port']]))
 
     def connect(self, node):
@@ -56,7 +67,7 @@ class SSH(object):
             pkey = None
             if 'priv_key' in node:
                 pkey = RSAKey.from_private_key(
-                        StringIO.StringIO(node['priv_key']))
+                    StringIO.StringIO(node['priv_key']))
 
             self._ssh = paramiko.SSHClient()
             self._ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
@@ -90,6 +101,8 @@ class SSH(object):
             ssh.close()
 
     def _reconnect(self):
+        """Close the SSH connection and open it again."""
+
         node = self._node
         self.disconnect(node)
         self.connect(node)
@@ -100,8 +113,8 @@ class SSH(object):
         """Execute SSH command on a new channel on the connected Node.
 
         :param cmd: Command to run on the Node.
-        :param timeout: Maximal time in seconds to wait while the command is
-        done. If is None then wait forever.
+        :param timeout: Maximal time in seconds to wait until the command is
+        done. If set to None then wait forever.
         :type cmd: str
         :type timeout: int
         :return return_code, stdout, stderr
@@ -203,7 +216,7 @@ class SSH(object):
 
         buf = ''
         try:
-            with timeout(time_out, exception=RuntimeError):
+            with icTimeout(time_out, exception=RuntimeError):
                 while not buf.endswith(':~$ '):
                     if chan.recv_ready():
                         buf = chan.recv(4096)
@@ -235,7 +248,7 @@ class SSH(object):
         chan.sendall('{c}\n'.format(c=cmd))
         buf = ''
         try:
-            with timeout(time_out, exception=RuntimeError):
+            with icTimeout(time_out, exception=RuntimeError):
                 while not buf.endswith(prompt):
                     if chan.recv_ready():
                         buf += chan.recv(4096)
@@ -283,8 +296,8 @@ def exec_cmd(node, cmd, timeout=600, sudo=False):
     ssh = SSH()
     try:
         ssh.connect(node)
-    except Exception, e:
-        logger.error("Failed to connect to node" + str(e))
+    except Exception as err:
+        logger.error("Failed to connect to node" + str(err))
         return None, None, None
 
     try:
@@ -293,8 +306,8 @@ def exec_cmd(node, cmd, timeout=600, sudo=False):
         else:
             (ret_code, stdout, stderr) = ssh.exec_command_sudo(cmd,
                                                                timeout=timeout)
-    except Exception, e:
-        logger.error(e)
+    except Exception as err:
+        logger.error(err)
         return None, None, None
 
     return ret_code, stdout, stderr
@@ -307,7 +320,7 @@ def exec_cmd_no_error(node, cmd, timeout=600, sudo=False):
 
     Returns (stdout, stderr).
     """
-    (rc, stdout, stderr) = exec_cmd(node, cmd, timeout=timeout, sudo=sudo)
-    assert_equal(rc, 0, 'Command execution failed: "{}"\n{}'.
+    (ret_code, stdout, stderr) = exec_cmd(node, cmd, timeout=timeout, sudo=sudo)
+    assert_equal(ret_code, 0, 'Command execution failed: "{}"\n{}'.
                  format(cmd, stderr))
     return stdout, stderr
diff --git a/resources/libraries/python/topology.py b/resources/libraries/python/topology.py
index c02991fbde..02f326a1df 100644
--- a/resources/libraries/python/topology.py
+++ b/resources/libraries/python/topology.py
@@ -34,6 +34,7 @@ def load_topo_from_yaml():
     with open(topo_path) as work_file:
         return load(work_file.read())['nodes']
 
+
 # pylint: disable=invalid-name
 class NodeType(object):
     """Defines node types used in topology dictionaries."""
@@ -46,6 +47,7 @@ class NodeType(object):
 
 
 class NodeSubTypeTG(object):
+    """Defines node sub-type TG - traffic generator."""
     # T-Rex traffic generator
     TREX = 'TREX'
     # Moongen
diff --git a/resources/tools/topology/update_topology.py b/resources/tools/topology/update_topology.py
index a5711d0922..f60fdf1653 100755
--- a/resources/tools/topology/update_topology.py
+++ b/resources/tools/topology/update_topology.py
@@ -59,7 +59,7 @@ def ssh_no_error(ssh, cmd):
     :rtype: str
     """
     ret, stdo, stde = ssh.exec_command(cmd)
-    if 0 != ret:
+    if ret != 0:
         print 'Command execution failed: "{}"'.format(cmd)
         print 'stdout: {0}'.format(stdo)
         print 'stderr: {0}'.format(stde)