Add the ability to specify PCI address in dpdk-bond-mappings.

[PanosKostopoulos]

Since mac addresses change often in deployment, an option for specifying PCI address is very useful.

[fnordahl]

1. The purpose of the resolve_pci_from_mapping_config function is to translate MAC into PCI addresses and as such I'd not modify it for your purpose.
   Instead, I'd suggest to create a new function that can be called from somewhere around here:

   charm-helpers/charmhelpers/contrib/openstack/context.py

   Lines 2698 to 2712 in 5488b35

   	def __call__(self):
   	"""Populate context.
   	:returns: context
   	:rtype: Dict[str,Union[str,collections.OrderedDict[str,str]]]
   	"""
   	driver = config(self.driver_key)
   	if driver is None:
   	return {}
   	# Resolve PCI devices for both directly used devices (_bridges)
   	# and devices for use in dpdk bonds (_bonds)
   	pci_devices = resolve_pci_from_mapping_config(self.bridges_key)
   	pci_devices.update(resolve_pci_from_mapping_config(self.bonds_key))
   	return {'devices': pci_devices,
   	'driver': driver}

2. Regular expressions are prohibitively difficult to read and maintain, please make use of the rich Python string helpers instead, there is some potential inspiration in the parse_* functions here:

   charm-helpers/charmhelpers/contrib/openstack/neutron.py

   Lines 274 to 351 in 5488b35

   	def parse_mappings(mappings, key_rvalue=False):
   	"""By default mappings are lvalue keyed.
   	If key_rvalue is True, the mapping will be reversed to allow multiple
   	configs for the same lvalue.
   	"""
   	parsed = {}
   	if mappings:
   	mappings = mappings.split()
   	for m in mappings:
   	p = m.partition(':')
   	if key_rvalue:
   	key_index = 2
   	val_index = 0
   	# if there is no rvalue skip to next
   	if not p[1]:
   	continue
   	else:
   	key_index = 0
   	val_index = 2
   	key = p[key_index].strip()
   	parsed[key] = p[val_index].strip()
   	return parsed
   	def parse_bridge_mappings(mappings):
   	"""Parse bridge mappings.
   	Mappings must be a space-delimited list of provider:bridge mappings.
   	Returns dict of the form {provider:bridge}.
   	"""
   	return parse_mappings(mappings)
   	def parse_data_port_mappings(mappings, default_bridge='br-data'):
   	"""Parse data port mappings.
   	Mappings must be a space-delimited list of bridge:port.
   	Returns dict of the form {port:bridge} where ports may be mac addresses or
   	interface names.
   	"""
   	# NOTE(dosaboy): we use rvalue for key to allow multiple values to be
   	# proposed for <port> since it may be a mac address which will differ
   	# across units this allowing first-known-good to be chosen.
   	_mappings = parse_mappings(mappings, key_rvalue=True)
   	if not _mappings or list(_mappings.values()) == ['']:
   	if not mappings:
   	return {}
   	# For backwards-compatibility we need to support port-only provided in
   	# config.
   	_mappings = {mappings.split()[0]: default_bridge}
   	ports = _mappings.keys()
   	if len(set(ports)) != len(ports):
   	raise Exception("It is not allowed to have the same port configured "
   	"on more than one bridge")
   	return _mappings
   	def parse_vlan_range_mappings(mappings):
   	"""Parse vlan range mappings.
   	Mappings must be a space-delimited list of provider:start:end mappings.
   	The start:end range is optional and may be omitted.
   	Returns dict of the form {provider: (start, end)}.
   	"""
   	_mappings = parse_mappings(mappings)
   	return {p: tuple(r.split(':')) for p, r in _mappings.items()}