ifup-os.in 9.36 KB
Newer Older
1 2 3 4
#!/bin/bash
#

# Copyright (C) 2014 Google Inc.
Klaus Aehlig's avatar
Klaus Aehlig committed
5
# All rights reserved.
6
#
Klaus Aehlig's avatar
Klaus Aehlig committed
7 8 9
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
10
#
Klaus Aehlig's avatar
Klaus Aehlig committed
11 12
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
13
#
Klaus Aehlig's avatar
Klaus Aehlig committed
14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 30 31 32 33 34 35 36 37 38 39

# This script is a hook called to configure new TAP network interfaces
# used for instance communication, and it should be called whenever a
# new instance is started.
#
# This script configures the new interface but it also performs
# maintenance on the network interfaces that have been configured
# before, by checking whether those TAP interfaces still exist, etc.
#
# This script also controls the DHCP server that leases IP address for
# instances, i.e., the NICs inside the instances, not the TAP
40
# interfaces.  The DHCP server is started and restarted
41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70
# as necessary and always with up-to-date configuration files.
#
# This script expects the following environment variables
#
#   INTERFACE: network interface name to be configured
#   MODE: networking mode for 'INTERFACE' (must be 'routed')
#   MAC: MAC address for 'INTERFACE'
#   IP: IP address for 'INTERFACE'

source @PKGLIBDIR@/net-common

readonly NETMASK=255.255.255.255
readonly DNSMASQ_CONF=/var/run/ganeti/dnsmasq.conf
readonly DNSMASQ_HOSTS=/var/run/ganeti/dnsmasq.hosts
readonly DNSMASQ_PID=/var/run/ganeti/dnsmasq.pid

# join intercalates a sequence of arguments using the given separator
function join {
  local IFS="$1"
  shift
  echo "$*"
}

# restart_dnsmasq restarts the DHCP server dnsmasq with the (possibly
# up-to-date) configuration file.
#
# If all instances have been terminated, which means there are no more
# TAP network interfaces to monitor or IP addresses to lease, the DHCP
# server is terminated through 'SIGTERM'.
#
71 72
# If there are still instances running, it will be restarted and the
# configuration file will be passed it.
73
function restart_dnsmasq {
74 75
  local RUNNING=
  local PID
76 77 78 79 80 81

  if [ -f "$DNSMASQ_PID" ]
  then
      PID=$(cat $DNSMASQ_PID)
      if [ -n "$PID" ] && ps -p "$PID"
      then
82
          RUNNING=yes
83 84 85 86 87
      fi
  fi

  if [ "$RUNNING" = yes ]
  then
88 89 90 91 92 93
      kill -TERM $PID
      # wait for the process to die
      while kill -0 $PID 2>/dev/null
      do
          sleep 1
      done
94 95 96
      rm -f $DNSMASQ_PID
  fi

97
  if [ -n "$ALIVE_INTERFACES" -a -n "$ALIVE_LEASES" ]
98
  then
99
      dnsmasq -C $DNSMASQ_CONF
100 101 102 103 104 105 106 107 108 109 110 111
  fi

  return 0
}

# Check that environment variable 'INTERFACE' exists.
#
# This environment variable holds the TAP network interface that
# should be configured by this script.  Ganeti always passes it,
# but... :)
if [ -z "$INTERFACE" ]
then
Jose A. Lopes's avatar
Jose A. Lopes committed
112
  echo ifup-os: Failed to configure communication mechanism \
113
      interface because the \'INTERFACE\' environment variable was \
Jose A. Lopes's avatar
Jose A. Lopes committed
114
      not specified to the script
115 116 117 118 119 120 121 122
  exit 1
fi

# Check that environment variable 'MODE' exists.
#
# See comment about environment variable 'INTERFACE'.
if [ -z "$MODE" ]
then
Jose A. Lopes's avatar
Jose A. Lopes committed
123
  echo ifup-os: Failed to configure communication mechanism \
124
      interface because the \'MODE\' environment variable was \
Jose A. Lopes's avatar
Jose A. Lopes committed
125
      not specified to the script
126 127 128 129 130 131 132 133 134 135 136 137
  exit 1
fi

# Check whether the interface being configured has instance
# communication enabled, otherwise exit this script.
if ! is_instance_communication_tap; then exit 0; fi

# Check that environment variable 'MAC' exists.
#
# See comment about environment variable 'INTERFACE'.
if [ -z "$MAC" ]
then
Jose A. Lopes's avatar
Jose A. Lopes committed
138
  echo ifup-os: Failed to configure communication mechanism \
139
      interface because the \'MAC\' environment variable was \
Jose A. Lopes's avatar
Jose A. Lopes committed
140
      not specified to the script
141 142 143 144 145 146 147 148
  exit 1
fi

# Check that environment variable 'IP' exists.
#
# See comment about environment variable 'INTERFACE'.
if [ -z "$IP" ]
then
Jose A. Lopes's avatar
Jose A. Lopes committed
149
  echo ifup-os: Failed to configure communication mechanism \
150
      interface because the \'IP\' environment variable was \
Jose A. Lopes's avatar
Jose A. Lopes committed
151
      not specified to the script
152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174
  exit 1
fi

# Configure the TAP interface
#
# Ganeti defers the configuration of instance network interfaces to
# hooks, therefore, we must configure the interface's network address,
# netmask, and IP address.
#
# The TAP network interface, which is used by the instance
# communication, is part of the network 169.254.0.0/16 and has the IP
# 169.254.169.254.  Because all network interfaces used in the
# instance communication have the same IP, the routing table must also
# be configured, and that is done at a later step.
#
# Note the interface must be marked as up before configuring the
# routing table and before starting/restarting the DHCP server.
#
# Note also that we don't have to check whether the interface is
# already configured because reconfiguring the interface with the same
# parameters does not produce an error.
ifconfig $INTERFACE 169.254.169.254 netmask $NETMASK up

175 176 177 178 179 180 181 182 183 184 185 186
# There is a known bug where UDP packets comming from a host to a XEN
# guest are missing checksums. There are several ways how to tackle the
# issue, for example fixing the checksums using iptables (requires a
# newer version):
#
# iptables -A POSTROUTING -t mangle -p udp --dport bootpc -j CHECKSUM \
#   --checksum-fill
#
# The easiest one currently seems to be to just turn checksumming off
# for this direction:
ethtool -K $INTERFACE tx off || true

187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226
# Configure the routing table
#
# Given that all TAP network interfaces in the instance communication
# have the same IP address, the routing table must be configured in
# order to properly route traffic from the host to the guests.
#
# Note that we must first check if a duplicate routing rule has
# already been added to the routing table, as this operation will fail
# if we try to add a routing rule that already exists.
ACTIVE_IP=$(ip route | grep "dev $INTERFACE" | awk '{ print $1 }')

if [ -z "$ACTIVE_IP" -o "$ACTIVE_IP" != "$IP" ]
then
  route add -host $IP dev $INTERFACE
fi

# Ensure the DHCP server configuration files exist
touch $DNSMASQ_CONF
chmod 0644 $DNSMASQ_CONF

touch $DNSMASQ_HOSTS
chmod 0644 $DNSMASQ_HOSTS

# Determine dnsmasq operational mode.
#
# The DHCP server dnsmasq can run in different modes.  In this version
# of the script, only the mode 'bind-dynamic' is supported.  Please
# refer to the dnsmasq FAQ for a detailed of each mode.
#
# Note that dnsmasq might already be running, therefore, we don't need
# to determine which modes are supported by this DHCP server.
# Instead, we just read the current mode from the configuration file.
DNSMASQ_MODE=$(head -n 1 $DNSMASQ_CONF)

if [ -z "$DNSMASQ_MODE" ]
then
  BIND_DYNAMIC=$(dnsmasq --help | grep -e --bind-dynamic)

  if [ -z "$BIND_DYNAMIC" ]
  then
Jose A. Lopes's avatar
Jose A. Lopes committed
227
    echo ifup-os: dnsmasq mode \"bind-dynamic\" is not supported
228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296
    exit 1
  fi

  DNSMASQ_MODE=bind-dynamic
fi

# Determine the interfaces that should go in the configuration file.
#
# The TAP network interfaces used by the instance communication are
# named after the following pattern
#
#  gnt.com.%d
#
# where '%d' is a unique number within the host.  Fortunately, dnsmasq
# supports binding to specific network interfaces via a pattern.
ALIVE_INTERFACES=${GANETI_TAP}.*

# Determine which of the leases are not duplicated and should go in
# the new configuration file for the DHCP server.
#
# Given that instances come and go, it is possible that we offer more
# leases that necessary and, worse, that we have duplicate leases,
# that is, the same IP address for the same/different MAC addresses.
# Duplicate leases must be eliminated before being written to the
# configuration file.
CONF_LEASES=$(cat $DNSMASQ_HOSTS)
CONF_LEASES=$(join $'\n' $CONF_LEASES | sort -u)

ALIVE_LEASES=( $MAC,$IP )

for i in $CONF_LEASES
do
  LEASE_MAC=$(echo $i | cut -d "," -f 1)
  LEASE_IP=$(echo $i | cut -d "," -f 2)
  if [ "$LEASE_MAC" != "$MAC" -a "$LEASE_IP" != "$IP" ]
  then
      ALIVE_LEASES=( ${ALIVE_LEASES[@]} $i )
  fi
done

ALIVE_LEASES=$(echo ${ALIVE_LEASES[@]} | sort -u)

# Update dnsmasq configuration.
#
# Write the parameters we have collected before into the new dnsmasq
# configuration file.  Also, write the new leases into the new dnsmasq
# hosts file.  Finally, restart dnsmasq with the new configuration
# files.
cat > $DNSMASQ_CONF <<EOF
$DNSMASQ_MODE
dhcp-authoritative
dhcp-hostsfile=$DNSMASQ_HOSTS
dhcp-range=169.254.0.0,static,255.255.0.0
except-interface=eth*
except-interface=lo
leasefile-ro
no-hosts
no-ping
no-resolv
pid-file=$DNSMASQ_PID
port=0
strict-order
EOF
for i in $ALIVE_INTERFACES; do echo interface=$i >> $DNSMASQ_CONF; done

echo -n > $DNSMASQ_HOSTS
for i in $ALIVE_LEASES; do echo $i >> $DNSMASQ_HOSTS; done

restart_dnsmasq