Better error messages when switch setup() fails.

mininet/moduledeps.py

@@ -47,19 +47,21 @@ def moduleDeps( subtract=None, add=None ):
             info( '*** Loading ' + mod + '\n' )
             modprobeOutput = modprobe( mod )
             if modprobeOutput:
-                error( 'Error inserting ' + mod + '- is it installed?\n' +
-                    'Error was: "%s"\n' % modprobeOutput )
+                error( 'Error inserting ' + mod + 
+                ' - is it installed and available via modprobe?\n' +
+                'Error was: "%s"\n' % modprobeOutput )
             if mod not in lsmod():
-                error( 'Failed to insert ' + mod + '\n' )
+                error( 'Failed to insert ' + mod + ' - quitting.\n' )
                 exit( 1 )
         else:
             debug( '*** ' + mod + ' already loaded\n' )
 
-def pathCheck( *args ):
+def pathCheck( *args, **kwargs ):
     "Make sure each program in *args can be found in $PATH."
+    moduleName = kwargs.get( 'moduleName', 'it' )
     for arg in args:
         if not quietRun( 'which ' + arg ):
-            error( 'Cannot find required executable %s -'
-                ' is it installed somewhere in your $PATH?\n(%s)\n' %
-                    ( arg, environ[ 'PATH' ] ) )
+            error( 'Cannot find required executable %s.\n' % arg +
+                'Please make sure that %s is installed ' % moduleName + 
+                'and available in your $PATH:\n(%s)\n' % environ[ 'PATH' ] )
             exit( 1 )

mininet/node.py

@@ -465,7 +465,8 @@ class UserSwitch( Switch ):
         """Init.
            name: name for the switch"""
         Switch.__init__( self, name, **kwargs )
-        pathCheck( 'ofdatapath', 'ofprotocol' )
+        pathCheck( 'ofdatapath', 'ofprotocol', 
+            moduleName='the OpenFlow reference user switch (openflow.org)' )
 
     @staticmethod
     def setup():
@@ -521,8 +522,10 @@ class KernelSwitch( Switch ):
     @staticmethod
     def setup():
         "Ensure any dependencies are loaded; if not, try to load them."
+        pathCheck( 'ofprotocol',
+            moduleName='the OpenFlow reference kernel switch'
+            ' (openflow.org) (NOTE: not available in OpenFlow 1.0!)' )
         moduleDeps( subtract=OVS_KMOD, add=OF_KMOD )
-        pathCheck( 'ofprotocol' )
 
     def start( self, controllers ):
         "Start up reference kernel datapath."
@@ -575,8 +578,9 @@ class OVSKernelSwitch( Switch ):
     @staticmethod
     def setup():
         "Ensure any dependencies are loaded; if not, try to load them."
-        moduleDeps( subtract = OF_KMOD, add = OVS_KMOD )
-        pathCheck( 'ovs-dpctl', 'ovs-openflowd' )
+        pathCheck( 'ovs-dpctl', 'ovs-openflowd',
+            moduleName='Open vSwitch (openvswitch.org)')
+        moduleDeps( subtract=OF_KMOD, add=OVS_KMOD )
 
     def start( self, controllers ):
         "Start up kernel datapath."