#!/usr/bin/python # # Copyright 2015 Cumulus Networks, Inc. All rights reserved. # # ''' The PolicyManager should be subclassed by addon modules to read a JSON policy config file that is later used to set defaults: Initialize: This module defines a list of config file location based on module. There are defined in the __init__(): All the addon modules need to do is import the policymanager module. import ifupdown.policymanager as policymanager Provides: an API to retrieve link attributes based on addon module name, interface name, and attribute. The ifupdown.policymanager module provides a global object policymanager_api that can be called like so: speed_default = policymanager.policymanager_api.get_default( module_name='ethtool', ifname=ifaceobj.name, attr='link-speed' ) ''' import json import logging import glob class policymanager(): def __init__(self): # we should check for these files in order # so that customers can override the /var/lib file settings self.logger = logging.getLogger('ifupdown.' + self.__class__.__name__) # we grab the json files from a known location and make sure that # the defaults_policy is checked first user_files = glob.glob('/etc/network/ifupdown2/policy.d/*.json') # grab the default module files default_files = glob.glob('/var/lib/ifupdown2/policy.d/*.json') # keep an array of defaults indexed by module name self.system_policy_array = {} for filename in default_files: system_array = {} try: fd = open(filename,'r') system_array = json.load(fd) self.logger.debug('reading %s system policy defaults config' \ % filename) except Exception, e: self.logger.info('could not read %s system policy defaults config' \ % filename) self.logger.info(' exception is %s' % str(e)) for module in system_array.keys(): if self.system_policy_array.has_key(module): self.logger.debug('warning: overwriting system module %s from file %s' \ % (module,filename)) self.system_policy_array[module] = system_array[module] # take care of user defined policy defaults self.user_policy_array = {} for filename in user_files: user_array = {} try: fd = open(filename,'r') user_array = json.load(fd) self.logger.debug('reading %s policy user defaults config' \ % filename) except Exception, e: self.logger.debug('could not read %s user policy defaults config' \ % filename) self.logger.debug(' exception is %s' % str(e)) # customer added module attributes for module in user_array.keys(): if self.system_policy_array.has_key(module): # warn user that we are overriding the system module setting self.logger.debug('warning: overwriting system with user module %s from file %s' \ % (module,filename)) self.user_policy_array[module] = user_array[module] return def get_iface_default(self,module_name=None,ifname=None,attr=None): ''' get_iface_default: Addon modules must use one of two types of access methods to the default configs. In this method, we expect the default to be either in [module]['iface_defaults'][ifname][attr] or [module]['defaults'][attr] We first check the user_policy_array and return that value. But if the user did not specify an override, we use the system_policy_array. ''' # make sure we have an index if (not ifname or not attr or not module_name): return None val = None # users can specify defaults to override the systemwide settings # look for user specific interface attribute iface_defaults first try: # looks for user specified value val = self.user_policy_array[module_name]['iface_defaults'][ifname][attr] return val except (TypeError, KeyError, IndexError): pass try: # failing that, there may be a user default for all intefaces val = self.user_policy_array[module_name]['defaults'][attr] return val except (TypeError, KeyError, IndexError): pass try: # failing that, look for system setting for the interface val = self.system_policy_array[module_name]['iface_defaults'][ifname][attr] return val except (TypeError, KeyError, IndexError): pass try: # failing that, look for system setting for all interfaces val = self.system_policy_array[module_name]['defaults'][attr] return val except (TypeError, KeyError, IndexError): pass # could not find any system or user default so return Non return val def get_attr_default(self,module_name=None,attr=None): ''' get_attr_default: Addon modules must use one of two types of access methods to the default configs. In this method, we expect the default to be in [module]['defaults'][attr] We first check the user_policy_array and return that value. But if the user did not specify an override, we use the system_policy_array. ''' if (not attr or not module_name): return None # users can specify defaults to override the systemwide settings # look for user specific attribute defaults first val = None try: # looks for user specified value val = self.user_policy_array[module_name]['defaults'][attr] return val except (TypeError, KeyError, IndexError): pass try: # failing that, look for system setting val = self.system_policy_array[module_name]['defaults'][attr] return val except (TypeError, KeyError, IndexError): pass return val def get_module_globals(self,module_name=None,attr=None): ''' get_module_globals: Addon modules must use one of two types of access methods to the default configs. In this method, we expect the default to be in [module]['module_globals'][attr] We first check the user_policy_array and return that value. But if the user did not specify an override, we use the system_policy_array. ''' if (not attr or not module_name): return None # users can specify defaults to override the systemwide settings # look for user specific attribute defaults first val = None try: # looks for user specified value val = self.user_policy_array[module_name]['module_globals'][attr] return val except (TypeError, KeyError, IndexError): pass try: # failing that, look for system setting val = self.system_policy_array[module_name]['module_globals'][attr] return val except (TypeError, KeyError, IndexError): pass return val def get_module_default(self,module_name=None): ''' get_module_default: Addon modules can also access the entire config This method returns indexed by "system" and "user": these are the system-wide and user-defined policy arrays for a specific module. ''' if not module_name: return None if self.system_policy_array.get(module_name) and \ self.user_policy_array.get(module_name): mod_array = {"system":self.system_policy_array[module_name], "user":self.user_policy_array[module_name]} else: # the module must not have these defined, return None mod_array = None return mod_array policymanager_api = policymanager()