lxc-network/lxc_net/parse_network.py

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2020-03-12 11:40:17 +01:00
import yaml
import sys
from . import network, container
class YamlTopology:
""" Parse a YAML description of a network topology. The networks' links and domains
are contained in the `links` and `domains` attributes, but their `create` methods
are not called. """
class InvalidConfiguration(Exception):
def __init__(self, reason):
self.reason = reason
def __str__(self):
return "Bad topology configuration: {}".format(self.reason)
def __init__(self, path, conn):
self.path = path
self.conn = conn
self.domains = None
self.links = None
self._parse()
def _parse(self):
with open(self.path, "r") as handle:
topology = yaml.safe_load(handle)
if "links" not in topology:
raise self.InvalidConfiguration("links definition is mandatory")
link_descr = topology["links"]
self.links = []
dom_descr = {}
for link_conf in link_descr:
if "domains" not in link_conf:
raise self.InvalidConfiguration(
"a 'domains' attribute is mandatory for each link"
)
cur_link = network.Network(self.conn)
self.links.append(cur_link)
for dom in link_conf["domains"]:
if dom not in dom_descr:
dom_descr[dom] = {"links": []}
dom_descr[dom]["links"].append(cur_link)
for dom_conf_name in topology.get("domains", None):
if dom_conf_name not in dom_descr:
# Domain does not participate in any link: warn and ignore
print(
(
"WARNING: domain {} does not participate in any link. "
"Ignored."
).format(dom_conf_name),
file=sys.stderr,
)
continue
dom_conf = topology["domains"][dom_conf_name]
dom_descr[dom_conf_name]["enable_v4"] = dom_conf.get("enable_v4", True)
sorted_dom_names = sorted(list(dom_descr.keys()))
self.domains = [
container.Container(
self.conn,
dom_descr[dom]["links"],
enable_v4=dom_descr[dom].get("enable_v4", True),
)
for dom in sorted_dom_names
]