Fixing pylint errors

examples/cluster.py

@@ -87,7 +87,7 @@ from signal import signal, SIGINT, SIG_IGN
 from subprocess import Popen, PIPE, STDOUT
 import os
 from random import randrange
-from sys import exit
+import sys
 import re
 
 from distutils.version import StrictVersion
@@ -282,7 +282,7 @@ class RemoteOVSSwitch( RemoteMixin, OVSSwitch ):
         cls = type( self )
         if self.server not in cls.OVSVersions:
             vers = self.cmd( 'ovs-vsctl --version' )
-            cls.OVSVersions[ self.server ] = re.findall( '\d+\.\d+', vers )[ 0 ]
+            cls.OVSVersions[ self.server ] = re.findall( r'\d+\.\d+', vers )[ 0 ]
         return ( StrictVersion( cls.OVSVersions[ self.server ] ) <
                 StrictVersion( '1.10' ) )
 
@@ -387,7 +387,7 @@ class RemoteLink( Link ):
             tunnel.wait()
             error( ch + tunnel.stdout.read() )
             error( tunnel.stderr.read() )
-            exit( 1 )
+            sys.exit( 1 )
         # 3. Move interfaces if necessary
         for node in node1, node2:
             if node.inNamespace:
@@ -660,7 +660,7 @@ class MininetCluster( Mininet ):
                    '*** Make sure that the above ssh command works correctly.\n'
                    '*** You may also need to run mn -c on all nodes, and/or\n'
                    '*** use sudo -E.\n' )
-            exit( 1 )
+            sys.exit( 1 )
         info( '\n' )
 
     def modifiedaddHost( self, *args, **kwargs ):

mininet/clean.py

@@ -10,7 +10,8 @@ It may also get rid of 'false positives', but hopefully
 nothing irreplaceable!
 """
 
-from subprocess import Popen, PIPE, check_output as co
+from subprocess import ( Popen, PIPE, check_output as co,
+                         CalledProcessError )
 import time
 
 from mininet.log import info
@@ -28,11 +29,11 @@ def killprocs( pattern ):
     # Make sure they are gone
     while True:
         try:
-            pids = co( 'pgrep -f %s' % pattern )
+            pids = co( [ 'pgrep', '-f', pattern ] )
-        except:
+        except CalledProcessError:
             pids = ''
         if pids:
-            sh( 'pkill -f 9 mininet:' )
+            sh( 'pkill -9 -f %s' % pattern )
             time.sleep( .5 )
         else:
             break

mininet/cli.py

@@ -96,7 +96,7 @@ class CLI( Cmd ):
     # Disable pylint "Unused argument: 'arg's'" messages, as well as
     # "method could be a function" warning, since each CLI function
     # must have the same interface
-    # pylint: disable-msg=R0201
+    # pylint: disable=R0201
 
     helpStr = (
         'You may also send a command to a node using:\n'
@@ -128,7 +128,7 @@ class CLI( Cmd ):
         nodes = ' '.join( sorted( self.mn ) )
         output( 'available nodes are: \n%s\n' % nodes )
 
-    def do_ports( self, line ):
+    def do_ports( self, _line ):
         "display ports and interfaces for each switch"
         dumpPorts( self.mn.switches )
 
@@ -142,7 +142,7 @@ class CLI( Cmd ):
         call( line, shell=True )
 
     # do_py() and do_px() need to catch any exception during eval()/exec()
-    # pylint: disable-msg=W0703
+    # pylint: disable=W0703
 
     def do_py( self, line ):
         """Evaluate a Python expression.
@@ -159,7 +159,7 @@ class CLI( Cmd ):
             output( str( e ) + '\n' )
 
     # We are in fact using the exec() pseudo-function
-    # pylint: disable-msg=W0122
+    # pylint: disable=W0122
 
     def do_px( self, line ):
         """Execute a Python statement.
@@ -169,7 +169,7 @@ class CLI( Cmd ):
         except Exception, e:
             output( str( e ) + '\n' )
 
-    # pylint: enable-msg=W0703,W0122
+    # pylint: enable=W0703,W0122
 
     def do_pingall( self, line ):
         "Ping between all hosts."
@@ -346,7 +346,7 @@ class CLI( Cmd ):
         elapsed = time.time() - start
         self.stdout.write("*** Elapsed time: %0.6f secs\n" % elapsed)
 
-    def do_links( self, line ):
+    def do_links( self, _line ):
         "Report on links"
         for link in self.mn.links:
             print link, link.status()
@@ -355,7 +355,8 @@ class CLI( Cmd ):
         "Starts or stops a switch"
         args = line.split()
         if len(args) != 2:
-            error( 'invalid number of args: switch <switch name> {start, stop}\n' )
+            error( 'invalid number of args: switch <switch name>'
+                   '{start, stop}\n' )
             return
         sw = args[ 0 ]
         command = args[ 1 ]
@@ -397,7 +398,7 @@ class CLI( Cmd ):
         else:
             error( '*** Unknown command: %s\n' % line )
 
-    # pylint: enable-msg=R0201
+    # pylint: enable=R0201
 
     def waitForNode( self, node ):
         "Wait for a node to finish, and print its output."

mininet/link.py

@@ -33,7 +33,7 @@ class Intf( object ):
     "Basic interface object that can configure itself."
 
     def __init__( self, name, node=None, port=None, link=None,
-                  mac=None, srcNode=None, **params ):
+                  mac=None, **params ):
         """name: interface name (e.g. h1-eth0)
            node: owning node (where this intf most likely lives)
            link: parent link if we're part of a link
@@ -71,7 +71,8 @@ class Intf( object ):
             return self.ifconfig( ipstr, 'up' )
         else:
             if prefixLen is None:
-                raise Exception( 'No prefix length set for IP address %s' % ( ipstr, ) )
+                raise Exception( 'No prefix length set for IP address %s'
+                                 % ( ipstr, ) )
             self.ip, self.prefixLen = ipstr, prefixLen
             return self.ifconfig( '%s/%s' % ( ipstr, prefixLen ) )
 
@@ -196,7 +197,7 @@ class Intf( object ):
 
     def status( self ):
         "Return intf status as a string"
-        links, err_, result_ = self.node.pexec( 'ip link show' )
+        links, _err, _result = self.node.pexec( 'ip link show' )
         if self.name in links:
             return "OK"
         else:
@@ -419,15 +420,19 @@ class Link( object ):
 
     def intfName( self, node, n ):
         "Construct a canonical interface name node-ethN for interface n."
+        # Leave this as an instance method for now
+        assert self
         return node.name + '-eth' + repr( n )
 
     @classmethod
-    def makeIntfPair( _cls, intfname1, intfname2, addr1=None, addr2=None ):
+    def makeIntfPair( cls, intfname1, intfname2, addr1=None, addr2=None ):
         """Create pair of interfaces
            intfname1: name of interface 1
            intfname2: name of interface 2
            (override this method [and possibly delete()]
            to change link type)"""
+        # Leave this as a class method for now
+        assert cls
         return makeIntfPair( intfname1, intfname2, addr1, addr2 )
 
     def delete( self ):

mininet/log.py

@@ -124,7 +124,7 @@ class MininetLogger( Logger, object ):
         self.setLevel( level )
         self.handlers[ 0 ].setLevel( level )
 
-    # pylint: disable-msg=E0202
+    # pylint: disable=E0202
     # "An attribute inherited from mininet.log hide this method"
     # Not sure why this is occurring - this function definitely gets called.
 
@@ -142,7 +142,7 @@ class MininetLogger( Logger, object ):
         if self.isEnabledFor( OUTPUT ):
             self._log( OUTPUT, msg, args, kwargs )
 
-    # pylint: enable-msg=E0202
+    # pylint: enable=E0202
 
 lg = MininetLogger()
 

mininet/net.py

@@ -98,7 +98,8 @@ from math import ceil
 
 from mininet.cli import CLI
 from mininet.log import info, error, debug, output, warn
-from mininet.node import Host, OVSKernelSwitch, DefaultController, Controller
+from mininet.node import ( Node, Host, OVSKernelSwitch, DefaultController,
+                          Controller )
 from mininet.nodelib import NAT
 from mininet.link import Link, Intf
 from mininet.util import quietRun, fixLimits, numCores, ensureRoot
@@ -264,14 +265,24 @@ class Mininet( object ):
             self.nameToNode[ name ] = controller_new
         return controller_new
 
-    def addNAT( self, name='nat0', connect=True, inNamespace=False, **params ):
+    def addNAT( self, name='nat0', connect=True, inNamespace=False,
+                **params):
+        """Add a NAT to the Mininet network
+           name: name of NAT node
+           connect: switch to connect to | True (s1) | None
+           inNamespace: create in a network namespace
+           params: other NAT node params, notably:
+               ip: used as default gateway address"""
         nat = self.addHost( name, cls=NAT, inNamespace=inNamespace,
                             subnet=self.ipBase, **params )
         # find first switch and create link
         if connect:
-            # connect the nat to the first switch
+            if not isinstance( connect, Node ):
+                # Use first switch if not specified
+                connect = self.switches[ 0 ]
+            # Connect the nat to the switch
             self.addLink( nat, self.switches[ 0 ] )
-            # set the default route on hosts
+            # Set the default route on hosts
             natIP = nat.params[ 'ip' ].split('/')[ 0 ]
             for host in self.hosts:
                 if host.inNamespace:
@@ -486,7 +497,8 @@ class Mininet( object ):
             info( '*** Stopping %i terms\n' % len( self.terms ) )
             self.stopXterms()
         info( '*** Stopping %i switches\n' % len( self.switches ) )
-        for swclass, switches in groupby( sorted( self.switches, key=type ), type ):
+        for swclass, switches in groupby(
+                sorted( self.switches, key=type ), type ):
             if hasattr( swclass, 'batchShutdown' ):
                 swclass.batchShutdown( switches )
         for switch in self.switches:
@@ -521,13 +533,13 @@ class Mininet( object ):
         if hosts is None:
             hosts = self.hosts
         poller = select.poll()
-        Node = hosts[ 0 ]  # so we can call class method fdToNode
+        h1 = hosts[ 0 ]  # so we can call class method fdToNode
         for host in hosts:
             poller.register( host.stdout )
         while True:
             ready = poller.poll( timeoutms )
             for fd, event in ready:
-                host = Node.fdToNode( fd )
+                host = h1.fdToNode( fd )
                 if event & select.POLLIN:
                     line = host.readline()
                     if line is not None:
@@ -574,7 +586,8 @@ class Mininet( object ):
                     if timeout:
                         opts = '-W %s' % timeout
                     if dest.intfs:
-                        result = node.cmd( 'ping -c1 %s %s' % (opts, dest.IP()) )
+                        result = node.cmd( 'ping -c1 %s %s' %
+                                           (opts, dest.IP()) )
                         sent, received = self._parsePing( result )
                     else:
                         sent, received = 0, 0
@@ -699,13 +712,13 @@ class Mininet( object ):
 
     # XXX This should be cleaned up
 
-    def iperf( self, hosts=None, l4Type='TCP', udpBw='10M', format=None,
+    def iperf( self, hosts=None, l4Type='TCP', udpBw='10M', fmt=None,
                seconds=5):
         """Run iperf between two hosts.
-           hosts: list of hosts; if None, uses opposite hosts
+           hosts: list of hosts; if None, uses first and last hosts
            l4Type: string, one of [ TCP, UDP ]
            udpBw: bandwidth target for UDP test
-           format: iperf format argument if any
+           fmt: iperf format argument if any
            seconds: iperf time to transmit
            returns: two-element array of [ server, client ] speeds
            note: send() is buffered, so client rate can be much higher than
@@ -729,8 +742,8 @@ class Mininet( object ):
             bwArgs = '-b ' + udpBw + ' '
         elif l4Type != 'TCP':
             raise Exception( 'Unexpected l4 type: %s' % l4Type )
-        if format:
+        if fmt:
-          iperfArgs += '-f %s ' %format
+            iperfArgs += '-f %s ' % fmt
         server.sendCmd( iperfArgs + '-s', printPid=True )
         servout = ''
         while server.lastPid is None:
@@ -755,7 +768,7 @@ class Mininet( object ):
     def runCpuLimitTest( self, cpu, duration=5 ):
         """run CPU limit test with 'while true' processes.
         cpu: desired CPU fraction of each host
-        duration: test duration in seconds
+        duration: test duration in seconds (integer)
         returns a single list of measured CPU fractions as floats.
         """
         cores = int( quietRun( 'nproc' ) )
@@ -776,12 +789,14 @@ class Mininet( object ):
         # get the initial cpu time for each host
         for host in hosts:
             outputs[ host ] = []
-            with open( '/sys/fs/cgroup/cpuacct/%s/cpuacct.usage' % host, 'r' ) as f:
+            with open( '/sys/fs/cgroup/cpuacct/%s/cpuacct.usage' %
+                       host, 'r' ) as f:
                 time[ host ] = float( f.read() )
-        for _ in range( 5 ):
+        for _ in range( duration ):
             sleep( 1 )
             for host in hosts:
-                with open( '/sys/fs/cgroup/cpuacct/%s/cpuacct.usage' % host, 'r' ) as f:
+                with open( '/sys/fs/cgroup/cpuacct/%s/cpuacct.usage' %
+                           host, 'r' ) as f:
                     readTime = float( f.read() )
                 outputs[ host ].append( ( ( readTime - time[ host ] )
                                         / 1000000000 ) / cores * 100 )

mininet/node.py

@@ -189,6 +189,8 @@ class Node( object ):
         """Internal method: spawn and return a process
             cmd: command to run (list)
             params: parameters to Popen()"""
+        # Leave this is as an instance method for now
+        assert self
         return Popen( cmd, **params )
 
     def cleanup( self ):
@@ -240,8 +242,11 @@ class Node( object ):
                 os.killpg( self.shell.pid, signal.SIGHUP )
         self.cleanup()
 
-    def stop( self ):
+    def stop( self, deleteIntfs=False ):
-        "Stop node."
+        """Stop node.
+           deleteIntfs: delete interfaces? (False)"""
+        if deleteIntfs:
+            self.deleteIntfs()
         self.terminate()
 
     def waitReadable( self, timeoutms=None ):
@@ -324,7 +329,7 @@ class Node( object ):
         log = info if verbose else debug
         output = ''
         while self.waiting:
-            data = self.monitor()
+            data = self.monitor( findPid=findPid )
             output += data
             log( data )
         return output
@@ -421,7 +426,7 @@ class Node( object ):
             warn( '*** defaultIntf: warning:', self.name,
                   'has no interfaces\n' )
 
-    def intf( self, intf='' ):
+    def intf( self, intf=None ):
         """Return our interface object with given string name,
            default intf if name is falsy (None, empty string, etc).
            or the input intf arg.
@@ -682,8 +687,8 @@ class CPULimitedHost( Host ):
             if int( self.cgroupGet( 'rt_runtime_us', 'cpu' ) ) <= 0:
                 mncmd += [ '-r', str( self.rtprio ) ]
             else:
-                debug( '*** error: not enough cpu time available for %s.' % self.name,
+                debug( '*** error: not enough cpu time available for %s.' %
-                      'Using cfs scheduler for subprocess\n' )
+                       self.name, 'Using cfs scheduler for subprocess\n' )
         return Host.popen( self, *args, mncmd=mncmd, **kwargs )
 
     def cleanup( self ):
@@ -698,9 +703,11 @@ class CPULimitedHost( Host ):
         "Check (Ubuntu,Debian) kernel config for CONFIG_RT_GROUP_SCHED for RT"
         if not cls._rtGroupSched:
             release = quietRun( 'uname -r' ).strip('\r\n')
-            output = quietRun( 'grep CONFIG_RT_GROUP_SCHED /boot/config-%s' % release )
+            output = quietRun( 'grep CONFIG_RT_GROUP_SCHED /boot/config-%s' %
+                               release )
             if output == '# CONFIG_RT_GROUP_SCHED is not set\n':
-                error( '\n*** error: please enable RT_GROUP_SCHED in your kernel\n' )
+                error( '\n*** error: please enable RT_GROUP_SCHED'
+                       'in your kernel\n' )
                 exit( 1 )
             cls._rtGroupSched = True
 
@@ -755,8 +762,8 @@ class CPULimitedHost( Host ):
             sched = self.sched
         if sched == 'rt':
             if not f or f < 0:
-                raise Exception( 'Please set a positive CPU fraction for sched=rt\n' )
+                raise Exception( 'Please set a positive CPU fraction'
-                return
+                                 ' for sched=rt\n' )
             pstr, qstr, period, quota = self.rtInfo( f )
         elif sched == 'cfs':
             pstr, qstr, period, quota = self.cfsInfo( f )
@@ -881,7 +888,8 @@ class Switch( Node ):
 
     def connected( self ):
         "Is the switch connected to a controller? (override this method)"
-        return False and self  # satisfy pylint
+        raise NotImplementedError( "connected() needs to be implemented in"
+                                   " Switch subclass %s" % self.__class__ )
 
     def __repr__( self ):
         "More informative string representation"
@@ -890,6 +898,7 @@ class Switch( Node ):
         return '<%s %s: %s pid=%s> ' % (
             self.__class__.__name__, self.name, intfs, self.pid )
 
+
 class UserSwitch( Switch ):
     "User-space switch."
 
@@ -982,7 +991,8 @@ class UserSwitch( Switch ):
                     self.TCReapply( intf )
 
     def stop( self, deleteIntfs=True ):
-        "Stop OpenFlow reference user datapath."
+        """Stop OpenFlow reference user datapath.
+           deleteIntfs: delete interfaces? (True)"""
         self.cmd( 'kill %ofdatapath' )
         self.cmd( 'kill %ofprotocol' )
         if deleteIntfs:
@@ -1033,7 +1043,8 @@ class OVSLegacyKernelSwitch( Switch ):
         self.execed = False
 
     def stop( self, deleteIntfs=True ):
-        "Terminate kernel datapath."
+        """Terminate kernel datapath."
+           deleteIntfs: delete interfaces? (True)"""
         quietRun( 'ovs-dpctl del-dp ' + self.dp )
         self.cmd( 'kill %ovs-openflowd' )
         if deleteIntfs:
@@ -1075,11 +1086,12 @@ class OVSSwitch( Switch ):
                    'You may wish to try '
                    '"service openvswitch-switch start".\n' )
             exit( 1 )
-        info = quietRun( 'ovs-vsctl --version' )
+        version = quietRun( 'ovs-vsctl --version' )
-        cls.OVSVersion =  findall( '\d+\.\d+', info )[ 0 ]
+        cls.OVSVersion =  findall( r'\d+\.\d+', version )[ 0 ]
 
     @classmethod
     def isOldOVS( cls ):
+        "Is OVS ersion < 1.10?"
         return ( StrictVersion( cls.OVSVersion ) <
              StrictVersion( '1.10' ) )
 
@@ -1186,7 +1198,8 @@ class OVSSwitch( Switch ):
 
 
     def stop( self, deleteIntfs=True ):
-        "Terminate OVS switch."
+        """Terminate OVS switch.
+           deleteIntfs: delete interfaces? (True)"""
         self.cmd( 'ovs-vsctl del-br', self )
         if self.datapath == 'user':
             self.cmd( 'ip link del', self )
@@ -1255,7 +1268,8 @@ class IVSSwitch( Switch ):
         self.cmd( ' '.join(args) + ' >' + logfile + ' 2>&1 </dev/null &' )
 
     def stop( self, deleteIntfs=True ):
-        "Terminate IVS switch."
+        """Terminate IVS switch.
+           deleteIntfs: delete interfaces? (True)"""
         self.cmd( 'kill %ivs' )
         self.cmd( 'wait' )
         if deleteIntfs:
@@ -1276,6 +1290,10 @@ class IVSSwitch( Switch ):
         return self.cmd( 'ovs-ofctl ' + ' '.join( args ) +
                          ' tcp:127.0.0.1:%i' % self.listenPort )
 
+    def connected( self ):
+        "For now, return True since we can't tell if we're connected"
+        return True
+
 
 class Controller( Node ):
     """A Controller is a Node that is running (or has execed?) an
@@ -1323,11 +1341,11 @@ class Controller( Node ):
                   ' 1>' + cout + ' 2>' + cout + ' &' )
         self.execed = False
 
-    def stop( self ):
+    def stop( self, *args, **kwargs ):
         "Stop controller."
         self.cmd( 'kill %' + self.command )
         self.cmd( 'wait %' + self.command )
-        self.terminate()
+        super( Controller, self ).stop( *args, **kwargs )
 
     def IP( self, intf=None ):
         "Return IP address of the Controller"
@@ -1343,7 +1361,8 @@ class Controller( Node ):
             self.__class__.__name__, self.name,
             self.IP(), self.port, self.pid )
     @classmethod
-    def isAvailable( self ):
+    def isAvailable( cls ):
+        "Is controller available?"
         return quietRun( 'which controller' )
 
 class OVSController( Controller ):
@@ -1353,8 +1372,9 @@ class OVSController( Controller ):
             command = 'test-controller'
         Controller.__init__( self, name, command=command, **kwargs )
     @classmethod
-    def isAvailable( self ):
+    def isAvailable( cls ):
-        return quietRun( 'which ovs-controller' ) or quietRun( 'which test-controller' )
+        return ( quietRun( 'which ovs-controller' ) or
+                 quietRun( 'which test-controller' ) )
 
 class NOX( Controller ):
     "Controller to run a NOX application."
@@ -1432,7 +1452,7 @@ class RemoteController( Controller ):
                   " at %s:%d\n" % ( self.ip, self.port ) )
 
 
-DefaultControllers = [ Controller, OVSController ]
+DefaultControllers = ( Controller, OVSController )
 
 def findController( controllers=DefaultControllers ):
     "Return first available controller from list, if any"
@@ -1446,4 +1466,3 @@ def DefaultController( name, controllers=DefaultControllers, **kwargs ):
     if not controller:
         raise Exception( 'Could not find a default OpenFlow controller' )
     return controller( name, **kwargs )
-

mininet/nodelib.py

@@ -33,7 +33,7 @@ class LinuxBridge( Switch ):
         else:
             return True
 
-    def start( self, controllers ):
+    def start( self, _controllers ):
         "Start Linux bridge"
         self.cmd( 'ifconfig', self, 'down' )
         self.cmd( 'brctl delbr', self )
@@ -62,21 +62,22 @@ class LinuxBridge( Switch ):
 
 
 class NAT( Node ):
-    """NAT: Provides connectivity to external network"""
+    "NAT: Provides connectivity to external network"
-
-    def __init__( self, name, inetIntf=None, subnet='10.0/8', localIntf=None, **params):
-        super( NAT, self ).__init__( name, **params )
 
+    def __init__( self, name, inetIntf=None, subnet='10.0/8',
+                  localIntf=None, **params):
         """Start NAT/forwarding between Mininet and external network
            inetIntf: interface for internet access
            subnet: Mininet subnet (default 10.0/8)="""
+        super( NAT, self ).__init__( name, **params )
+
         self.inetIntf = inetIntf if inetIntf else self.getGatewayIntf()
         self.subnet = subnet
         self.localIntf = localIntf
 
     def config( self, **params ):
-        super( NAT, self).config( **params )
         """Configure the NAT and iptables"""
+        super( NAT, self).config( **params )
 
         if not self.localIntf:
             self.localIntf =  self.defaultIntf()
@@ -94,10 +95,14 @@ class NAT( Node ):
         self.cmd( 'iptables -P FORWARD DROP' )
 
         # Configure NAT
-        self.cmd( 'iptables -I FORWARD -i', self.localIntf, '-d', self.subnet, '-j DROP' )
+        self.cmd( 'iptables -I FORWARD',
-        self.cmd( 'iptables -A FORWARD -i', self.localIntf, '-s', self.subnet, '-j ACCEPT' )
+                  '-i', self.localIntf, '-d', self.subnet, '-j DROP' )
-        self.cmd( 'iptables -A FORWARD -i', self.inetIntf, '-d', self.subnet, '-j ACCEPT' )
+        self.cmd( 'iptables -A FORWARD',
-        self.cmd( 'iptables -t nat -A POSTROUTING -o ', self.inetIntf, '-s', self.subnet, '-j MASQUERADE' )
+                  '-i', self.localIntf, '-s', self.subnet, '-j ACCEPT' )
+        self.cmd( 'iptables -A FORWARD',
+                  '-i', self.inetIntf, '-d', self.subnet, '-j ACCEPT' )
+        self.cmd( 'iptables -t nat -A POSTROUTING',
+                  '-o', self.inetIntf, '-s', self.subnet, '-j MASQUERADE' )
 
         # Instruct the kernel to perform forwarding
         self.cmd( 'sysctl net.ipv4.ip_forward=1' )
@@ -116,14 +121,17 @@ class NAT( Node ):
         # hopefully this won't disconnect you
         self.cmd( 'service network-manager restart' )
 
-    def getGatewayIntf( self ):
+    def getGatewayIntf( self, fallback='eth0' ):
+        """Return gateway interface name
+           fallback: default device to fall back to"""
         routes = self.cmd( 'ip route show' )
-        match = re.search('default via \S+ dev (\S+)', routes )
+        match = re.search( r'default via \S+ dev (\S+)', routes )
         if match:
             return match.group( 1 )
         else:
-            warn( 'There is no default route set. Using eth0 as gateway interface...\n' )
+            warn( 'There is no default route set.',
-            return 'eth0'
+                  'Using', fallback, 'as gateway interface...\n' )
+            return fallback
 
     def terminate( self ):
         """Stop NAT/forwarding between Mininet and external network"""
@@ -136,4 +144,3 @@ class NAT( Node ):
         self.cmd( 'sysctl net.ipv4.ip_forward=0' )
 
         super( NAT, self ).terminate()
-

mininet/topo.py

@@ -111,7 +111,8 @@ class Topo( object ):
         self.hopts = params.pop( 'hopts', {} )
         self.sopts = params.pop( 'sopts', {} )
         self.lopts = params.pop( 'lopts', {} )
-        self.ports = {}  # ports[src][dst][sport] is port on dst that connects to src
+        # ports[src][dst][sport] is port on dst that connects to src
+        self.ports = {}
         self.build( *args, **params )
 
     def build( self, *args, **params ):
@@ -187,7 +188,7 @@ class Topo( object ):
            withKeys: return link keys
            withInfo: return link info
            returns: list of ( src, dst [,key, info ] )"""
-        for src, dst, key, info in self.g.edges_iter( data=True, keys=True ):
+        for _src, _dst, key, info in self.g.edges_iter( data=True, keys=True ):
             node1, node2 = info[ 'node1' ], info[ 'node2' ]
             if withKeys:
                 if withInfo:
@@ -207,7 +208,7 @@ class Topo( object ):
            withInfo: return link info
            returns: list of ( src, dst [,key, info ] )"""
         links = list( self.iterLinks( withKeys, withInfo ) )
-        if not sorted:
+        if not sort:
             return links
         # Ignore info when sorting
         tupleSize = 3 if withKeys else 2
@@ -287,10 +288,13 @@ class Topo( object ):
         return sorted( items, key=natural )
 
 
+# Our idiom defines additional parameters in build(param...)
+# pylint: disable=arguments-differ, attribute-defined-outside-init
+
 class SingleSwitchTopo( Topo ):
     "Single switch connected to k hosts."
 
-    def build( self, k=2, **opts ):
+    def build( self, k=2, **_opts ):
         "k: number of hosts"
         self.k = k
         switch = self.addSwitch( 's1' )
@@ -317,7 +321,7 @@ class SingleSwitchReversedTopo( Topo ):
 class LinearTopo( Topo ):
     "Linear topology of k switches, with n hosts per switch."
 
-    def build( self, k=2, n=1, **opts):
+    def build( self, k=2, n=1, **_opts):
         """k: number of switches
            n: number of hosts per switch"""
         self.k = k
@@ -340,3 +344,5 @@ class LinearTopo( Topo ):
             if lastSwitch:
                 self.addLink( switch, lastSwitch )
             lastSwitch = switch
+
+# pylint: enable=arguments-differ, attribute-defined-outside-init

mininet/topolib.py

@@ -3,6 +3,9 @@
 from mininet.topo import Topo
 from mininet.net import Mininet
 
+# The build() method is expected to do both of these things:
+# pylint: disable=attribute-defined-outside-init, arguments-differ
+
 class TreeTopo( Topo ):
     "Topology for a tree network with a given depth and fanout."
 
@@ -53,7 +56,8 @@ class TorusTopo( Topo ):
                 loc = '%dx%d' % ( i + 1, j + 1 )
                 # dpid cannot be zero for OVS
                 dpid = ( i + 1 ) * 256 + ( j + 1 )
-                switch = switches[ i, j ] = self.addSwitch( 's' + loc, dpid='%016x' % dpid )
+                switch = switches[ i, j ] = self.addSwitch(
+                    's' + loc, dpid='%016x' % dpid )
                 host = hosts[ i, j ] = self.addHost( 'h' + loc )
                 self.addLink( host, switch )
         # Connect switches
@@ -65,5 +69,4 @@ class TorusTopo( Topo ):
                 self.addLink( sw1, sw2 )
                 self.addLink( sw1, sw3 )
 
-
+# pylint: enable=attribute-defined-outside-init, arguments-differ
-

mininet/util.py

@@ -25,7 +25,7 @@ def checkRun( cmd ):
     return check_call( cmd.split( ' ' ) )
 
 # pylint doesn't understand explicit type checking
-# pylint: disable-msg=E1103
+# pylint: disable=E1103
 
 def oldQuietRun( *cmd ):
     """Run a command, routing stderr to stdout, and return the output.
@@ -119,8 +119,8 @@ def quietRun( cmd, **kwargs ):
     "Run a command and return merged stdout and stderr"
     return errRun( cmd, stderr=STDOUT, **kwargs )[ 0 ]
 
-# pylint: enable-msg=E1103
+# pylint: enable=E1103
-# pylint: disable-msg=E1101
+# pylint: disable=E1101
 
 def isShellBuiltin( cmd ):
     "Return True if cmd is a bash builtin."
@@ -133,7 +133,7 @@ def isShellBuiltin( cmd ):
 
 isShellBuiltin.builtIns = None
 
-# pylint: enable-msg=E1101
+# pylint: enable=E1101
 
 # Interface management
 #
@@ -148,22 +148,22 @@ isShellBuiltin.builtIns = None
 # live in the root namespace and thus do not have to be
 # explicitly moved.
 
-def makeIntfPair( intf1, intf2, addr1=None, addr2=None, run=quietRun ):
+def makeIntfPair( intf1, intf2, addr1=None, addr2=None, runCmd=quietRun ):
     """Make a veth pair connecting intf1 and intf2.
        intf1: string, interface
        intf2: string, interface
-       node: node to run on or None (default)
+       runCmd: function to run shell commands (quietRun)
        returns: ip link add result"""
     # Delete any old interfaces with the same names
-    run( 'ip link del ' + intf1 )
+    runCmd( 'ip link del ' + intf1 )
-    run( 'ip link del ' + intf2 )
+    runCmd( 'ip link del ' + intf2 )
     # Create new pair
     if addr1 is None and addr2 is None:
         cmd = 'ip link add name ' + intf1 + ' type veth peer name ' + intf2
     else:
         cmd = ( 'ip link add name ' + intf1 + ' address ' + addr1 +
                 ' type veth peer name ' + intf2 + ' address ' + addr2 )
-    cmdOutput = run( cmd )
+    cmdOutput = runCmd( cmd )
     if cmdOutput == '':
         return True
     else:
@@ -202,7 +202,7 @@ def moveIntfNoRetry( intf, dstNode, printError=False ):
         return False
     return True
 
-def moveIntf( intf, dstNode, srcNode=None, printError=True,
+def moveIntf( intf, dstNode, printError=True,
              retries=3, delaySecs=0.001 ):
     """Move interface to node, retrying on failure.
        intf: string, interface
@@ -296,7 +296,7 @@ def ipAdd( i, prefixLen=8, ipBaseNum=0x0a000000 ):
 def ipParse( ip ):
     "Parse an IP address and return an unsigned int."
     args = [ int( arg ) for arg in ip.split( '.' ) ]
-    while ( len(args) < 4 ):
+    while len(args) < 4:
         args.append( 0 )
     return ipNum( *args )
 
@@ -427,7 +427,7 @@ def fixLimits():
         sysctlTestAndSet( 'net.ipv4.route.max_size', 32768 )
         #Increase number of PTYs for nodes
         sysctlTestAndSet( 'kernel.pty.max', 20000 )
-    except:
+    except Exception:
         warn( "*** Error setting resource limits. "
               "Mininet's performance may be affected.\n" )
 
@@ -545,9 +545,9 @@ def ensureRoot():
 def waitListening( client=None, server='127.0.0.1', port=80, timeout=None ):
     """Wait until server is listening on port.
        returns True if server is listening"""
-    run = ( client.cmd if client else
+    runCmd = ( client.cmd if client else
                 partial( quietRun, shell=True ) )
-    if not run( 'which telnet' ):
+    if not runCmd( 'which telnet' ):
         raise Exception('Could not find telnet' )
     serverIP = server if isinstance( server, basestring ) else server.IP()
     cmd = ( 'sh -c "echo A | telnet -e A %s %s"' %