mirror of https://github.com/zulip/zulip.git
99 lines
3.7 KiB
Python
Executable File
99 lines
3.7 KiB
Python
Executable File
#!/usr/bin/python
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# -*- coding: utf-8 -*-
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'''Configure a host for EC2-VPC dynamically assigned network interfaces
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Amazon VPC gives us a good deal of flexibility compared to classic EC2.
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However there are limitations; you can assign multiple IPs to a host
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yet only the first IP per interface will be DHCP assigned, and you are
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limited in the total number of interfaces you have, so doing one-IP-per-
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interface is also untenable.
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This script grabs the metadata provided by AWS and uses it to correctly
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configure all available network interfaces.
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It is suitable to be hooked in to system boot and network
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reconfiguration scripts.
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Note that it currently does not handle the deconfiguration of
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interfaces.
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'''
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import sys
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import logging
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import logging.handlers
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import subprocess
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import re
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import boto.utils
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import netifaces
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def address_of(device_id):
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try:
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return netifaces.ifaddresses("eth%i" % device_id)[netifaces.AF_INET][0]['addr']
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except KeyError:
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return None
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def guess_gateway(device_id):
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# This will not work if the default gateway isn't n.n.n.1.
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address = address_of(device_id).split('.')
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address[3] = '1'
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return '.'.join(address)
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log = logging.getLogger('ec2ify')
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log.setLevel(logging.DEBUG)
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log.addHandler(logging.handlers.SysLogHandler(facility=logging.handlers.SysLogHandler.LOG_DAEMON))
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log.addHandler(logging.StreamHandler())
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log.info("ec2ify starting")
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macs = boto.utils.get_instance_metadata()["network"]["interfaces"]["macs"]
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ids = [int(macdata['device-number']) for macdata in macs.values()]
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ifaces = [iface for iface in netifaces.interfaces() if ":" not in iface and iface != "lo"]
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# Number of IDs should equal number of interfaces
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if len(ids) != len(ifaces):
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log.error("Metadata indicated %i interfaces but we have %i!" % (len(ids), len(ifaces)))
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sys.exit(1)
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for device in macs.values():
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# There's an annoying API inconsistency here:
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# If you have multiple IPs, local-ipv4s is a list.
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# If you only have one, local-ipv4s is a string.
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# Who knew?
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if type(device['local-ipv4s']) is str:
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# Only do dhcp, don't try to assign addresses
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to_configure = [device['local-ipv4s']]
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else:
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to_configure = list(device['local-ipv4s'])
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device_number = int(device['device-number'])
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if address_of(device_number) is None:
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# If the device was not autoconfigured, do so now.
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log.info("Device eth%i not configured, starting dhcpd" % device_number)
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subprocess.check_call(['/sbin/dhcpcd', 'eth%i' % device_number])
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# Horrible hack to route return packets on the correct interface
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# See http://unix.stackexchange.com/a/4421/933
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subprocess.check_call(
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['/sbin/ip', 'rule', 'add', 'fwmark', str(device_number), 'table', str(device_number)])
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subprocess.check_call(
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['/sbin/ip', 'route', 'add', '0.0.0.0/0', 'table', str(device_number), 'dev',
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'eth%i' % device_number, 'via', guess_gateway(device_number)])
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subprocess.check_call(
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['/sbin/iptables', '-t', 'mangle', '-A', 'OUTPUT', '-m', 'conntrack', '--ctorigdst',
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address_of(device_number), '-j', 'MARK', '--set-mark', str(device_number)])
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to_configure.remove(address_of(device_number))
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for (count, ip) in enumerate(to_configure):
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# Configure the IP via a virtual interface
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device = "eth%i:%i" % (device_number, count)
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log.info("Configuring %s with IP %s" % (device, ip))
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subprocess.check_call(['/sbin/ifconfig', device, ip])
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for throwaway in range(2):
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# Don't freak out if this doens't work.
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subprocess.call(
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['/sbin/ip', 'route', 'del', '10.0.0.0/8'])
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