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-rw-r--r--cloudinit/net/__init__.py82
1 files changed, 80 insertions, 2 deletions
diff --git a/cloudinit/net/__init__.py b/cloudinit/net/__init__.py
index 799cb97e..b45153f4 100644
--- a/cloudinit/net/__init__.py
+++ b/cloudinit/net/__init__.py
@@ -20,6 +20,7 @@ import errno
import glob
import os
import re
+import string
from cloudinit import log as logging
from cloudinit import util
@@ -46,6 +47,8 @@ NET_CONFIG_BRIDGE_OPTIONS = [
"bridge_hello", "bridge_maxage", "bridge_maxwait", "bridge_stp",
]
+DEFAULT_PRIMARY_INTERFACE = 'eth0'
+
def sys_dev_path(devname, path=""):
return SYS_CLASS_NET + devname + "/" + path
@@ -442,8 +445,83 @@ def is_disabled_cfg(cfg):
def generate_fallback_config():
- # FIXME: add implementation here
- return None
+ """Determine which attached net dev is most likely to have a connection and
+ generate network state to run dhcp on that interface"""
+ # by default use eth0 as primary interface
+ nconf = {'config': {'interfaces': {},
+ 'dns': {'search': [], 'nameservers': []}, 'routes': []
+ },
+ 'version': 1
+ }
+
+ # get list of interfaces that could have connections
+ invalid_interfaces = set(['lo'])
+ potential_interfaces = set(os.listdir(SYS_CLASS_NET))
+ potential_interfaces = potential_interfaces.difference(invalid_interfaces)
+ # sort into interfaces with carrier, interfaces which could have carrier,
+ # and ignore interfaces that are definitely disconnected
+ connected = []
+ possibly_connected = []
+ for interface in potential_interfaces:
+ try:
+ sysfs_carrier = os.path.join(SYS_CLASS_NET, interface, 'carrier')
+ carrier = int(util.load_file(sysfs_carrier).strip())
+ if carrier:
+ connected.append(interface)
+ continue
+ except OSError:
+ pass
+ # check if nic is dormant or down, as this may make a nick appear to
+ # not have a carrier even though it could acquire one when brought
+ # online by dhclient
+ try:
+ sysfs_dormant = os.path.join(SYS_CLASS_NET, interface, 'dormant')
+ dormant = int(util.load_file(sysfs_dormant).strip())
+ if dormant:
+ possibly_connected.append(interface)
+ continue
+ except OSError:
+ pass
+ try:
+ sysfs_operstate = os.path.join(SYS_CLASS_NET, interface,
+ 'operstate')
+ operstate = util.load_file(sysfs_operstate).strip()
+ if operstate in ['dormant', 'down', 'lowerlayerdown', 'unknown']:
+ possibly_connected.append(interface)
+ continue
+ except OSError:
+ pass
+
+ # don't bother with interfaces that might not be connected if there are
+ # some that definitely are
+ if connected:
+ potential_interfaces = connected
+ else:
+ potential_interfaces = possibly_connected
+ # if there are no interfaces, give up
+ if not potential_interfaces:
+ return
+ # if eth0 exists use it above anything else, otherwise get the interface
+ # that looks 'first'
+ if DEFAULT_PRIMARY_INTERFACE in potential_interfaces:
+ name = DEFAULT_PRIMARY_INTERFACE
+ else:
+ potential_interfaces.sort(
+ key=lambda x: int(''.join(i for i in x if i in string.digits)))
+ name = potential_interfaces[0]
+
+ sysfs_mac = os.path.join(SYS_CLASS_NET, name, 'address')
+ mac = util.load_file(sysfs_mac).strip()
+ target_name = name
+
+ # generate net config for interface
+ nconf['config']['interfaces'][target_name] = {
+ 'mac_address': mac, 'name': target_name, 'type': 'physical',
+ 'mode': 'manual', 'inet': 'inet',
+ 'subnets': [{'type': 'dhcp4'}, {'type': 'dhcp6'}]
+ }
+
+ return nconf
def read_kernel_cmdline_config():