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#!/bin/bash |
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# |
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# Copyright (C) 2014 Google Inc. |
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# |
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# This program is free software; you can redistribute it and/or modify |
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# it under the terms of the GNU General Public License as published by |
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# the Free Software Foundation; either version 2 of the License, or |
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# (at your option) any later version. |
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# |
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# This program is distributed in the hope that it will be useful, but |
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# WITHOUT ANY WARRANTY; without even the implied warranty of |
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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# General Public License for more details. |
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# |
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# You should have received a copy of the GNU General Public License |
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# along with this program; if not, write to the Free Software |
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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# 02110-1301, USA. |
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|
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# This script is a hook called to configure new TAP network interfaces |
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# used for instance communication, and it should be called whenever a |
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# new instance is started. |
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# |
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# This script configures the new interface but it also performs |
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# maintenance on the network interfaces that have been configured |
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# before, by checking whether those TAP interfaces still exist, etc. |
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# |
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# This script also controls the DHCP server that leases IP address for |
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# instances, i.e., the NICs inside the instances, not the TAP |
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# interfaces. The DHCP server is started and restarted (or reHUPed) |
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# as necessary and always with up-to-date configuration files. |
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# |
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# This script expects the following environment variables |
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# |
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# INTERFACE: network interface name to be configured |
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# MODE: networking mode for 'INTERFACE' (must be 'routed') |
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# MAC: MAC address for 'INTERFACE' |
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# IP: IP address for 'INTERFACE' |
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|
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source @PKGLIBDIR@/net-common |
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|
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readonly NETMASK=255.255.255.255 |
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readonly DNSMASQ_CONF=/var/run/ganeti/dnsmasq.conf |
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readonly DNSMASQ_HOSTS=/var/run/ganeti/dnsmasq.hosts |
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readonly DNSMASQ_PID=/var/run/ganeti/dnsmasq.pid |
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|
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# join intercalates a sequence of arguments using the given separator |
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function join { |
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local IFS="$1" |
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shift |
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echo "$*" |
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} |
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|
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# restart_dnsmasq restarts the DHCP server dnsmasq with the (possibly |
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# up-to-date) configuration file. |
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# |
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# If all instances have been terminated, which means there are no more |
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# TAP network interfaces to monitor or IP addresses to lease, the DHCP |
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# server is terminated through 'SIGTERM'. |
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# |
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# If there are still instances running, then: |
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# - if the DHCP server is running, a 'SIGHUP' will be sent to the |
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# dnsmasq process which will cause the configuration file to be |
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# re-read, while keeping the process running |
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# - if the DHCP server is not running, it will be started, and the |
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# configuration file will be passed it |
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function restart_dnsmasq { |
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SIGNAL= |
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|
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if [ -z "$ALIVE_INTERFACES" -o -z "$ALIVE_LEASES" ] |
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then |
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SIGNAL=TERM |
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else |
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SIGNAL=HUP |
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fi |
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|
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RUNNING= |
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|
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if [ -f "$DNSMASQ_PID" ] |
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then |
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PID=$(cat $DNSMASQ_PID) |
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if [ -n "$PID" ] && ps -p "$PID" |
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then |
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RUNNING=yes |
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fi |
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fi |
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|
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KILLED= |
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|
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if [ "$RUNNING" = yes ] |
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then |
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kill -$SIGNAL $PID |
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|
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if [ "$SIGNAL" = TERM ] |
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then |
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KILLED=yes |
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fi |
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fi |
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|
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if [ "$KILLED" = yes ] |
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then |
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rm -f $DNSMASQ_PID |
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fi |
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|
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if [ "$RUNNING" != yes -o "$KILLED" == yes ] |
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then |
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if [ -n "$ALIVE_INTERFACES" -a -n "$ALIVE_LEASES" ] |
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then |
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dnsmasq -C $DNSMASQ_CONF |
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fi |
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fi |
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|
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return 0 |
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} |
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|
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# Check that environment variable 'INTERFACE' exists. |
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# |
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# This environment variable holds the TAP network interface that |
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# should be configured by this script. Ganeti always passes it, |
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# but... :) |
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if [ -z "$INTERFACE" ] |
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then |
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echo kvm-vif-bridge: Failed to configure communication mechanism \ |
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interface because the \'INTERFACE\' environment variable was \ |
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not specified to the \'kvm-vif-bridge\' script |
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exit 1 |
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fi |
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|
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# Check that environment variable 'MODE' exists. |
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# |
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# See comment about environment variable 'INTERFACE'. |
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if [ -z "$MODE" ] |
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then |
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echo kvm-vif-bridge: Failed to configure communication mechanism \ |
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interface because the \'MODE\' environment variable was \ |
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not specified to the \'kvm-vif-bridge\' script |
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exit 1 |
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fi |
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|
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# Check whether the interface being configured has instance |
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# communication enabled, otherwise exit this script. |
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if ! is_instance_communication_tap; then exit 0; fi |
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|
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# Check that environment variable 'MAC' exists. |
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# |
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# See comment about environment variable 'INTERFACE'. |
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if [ -z "$MAC" ] |
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then |
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echo kvm-vif-bridge: Failed to configure communication mechanism \ |
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interface because the \'MAC\' environment variable was \ |
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not specified to the \'kvm-vif-bridge\' script |
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exit 1 |
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fi |
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|
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# Check that environment variable 'IP' exists. |
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# |
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# See comment about environment variable 'INTERFACE'. |
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if [ -z "$IP" ] |
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then |
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echo kvm-vif-bridge: Failed to configure communication mechanism \ |
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interface because the \'IP\' environment variable was \ |
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not specified to the \'kvm-vif-bridge\' script |
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exit 1 |
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fi |
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|
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# Configure the TAP interface |
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# |
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# Ganeti defers the configuration of instance network interfaces to |
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# hooks, therefore, we must configure the interface's network address, |
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# netmask, and IP address. |
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# |
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# The TAP network interface, which is used by the instance |
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# communication, is part of the network 169.254.0.0/16 and has the IP |
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# 169.254.169.254. Because all network interfaces used in the |
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# instance communication have the same IP, the routing table must also |
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# be configured, and that is done at a later step. |
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# |
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# Note the interface must be marked as up before configuring the |
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# routing table and before starting/restarting the DHCP server. |
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# |
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# Note also that we don't have to check whether the interface is |
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# already configured because reconfiguring the interface with the same |
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# parameters does not produce an error. |
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ifconfig $INTERFACE 169.254.169.254 netmask $NETMASK up |
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|
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# Configure the routing table |
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# |
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# Given that all TAP network interfaces in the instance communication |
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# have the same IP address, the routing table must be configured in |
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# order to properly route traffic from the host to the guests. |
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# |
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# Note that we must first check if a duplicate routing rule has |
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# already been added to the routing table, as this operation will fail |
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# if we try to add a routing rule that already exists. |
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ACTIVE_IP=$(ip route | grep "dev $INTERFACE" | awk '{ print $1 }') |
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|
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if [ -z "$ACTIVE_IP" -o "$ACTIVE_IP" != "$IP" ] |
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then |
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route add -host $IP dev $INTERFACE |
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fi |
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|
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# Ensure the DHCP server configuration files exist |
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touch $DNSMASQ_CONF |
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chmod 0644 $DNSMASQ_CONF |
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|
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touch $DNSMASQ_HOSTS |
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chmod 0644 $DNSMASQ_HOSTS |
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|
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# Determine dnsmasq operational mode. |
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# |
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# The DHCP server dnsmasq can run in different modes. In this version |
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# of the script, only the mode 'bind-dynamic' is supported. Please |
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# refer to the dnsmasq FAQ for a detailed of each mode. |
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# |
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# Note that dnsmasq might already be running, therefore, we don't need |
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# to determine which modes are supported by this DHCP server. |
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# Instead, we just read the current mode from the configuration file. |
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DNSMASQ_MODE=$(head -n 1 $DNSMASQ_CONF) |
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|
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if [ -z "$DNSMASQ_MODE" ] |
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then |
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BIND_DYNAMIC=$(dnsmasq --help | grep -e --bind-dynamic) |
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|
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if [ -z "$BIND_DYNAMIC" ] |
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then |
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echo kvm-vif-bridge: dnsmasq mode \"bind-dynamic\" is not supported |
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exit 1 |
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fi |
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|
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DNSMASQ_MODE=bind-dynamic |
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fi |
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|
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# Determine the interfaces that should go in the configuration file. |
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# |
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# The TAP network interfaces used by the instance communication are |
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# named after the following pattern |
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# |
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# gnt.com.%d |
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# |
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# where '%d' is a unique number within the host. Fortunately, dnsmasq |
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# supports binding to specific network interfaces via a pattern. |
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ALIVE_INTERFACES=${GANETI_TAP}.* |
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|
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# Determine which of the leases are not duplicated and should go in |
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# the new configuration file for the DHCP server. |
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# |
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# Given that instances come and go, it is possible that we offer more |
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# leases that necessary and, worse, that we have duplicate leases, |
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# that is, the same IP address for the same/different MAC addresses. |
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# Duplicate leases must be eliminated before being written to the |
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# configuration file. |
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CONF_LEASES=$(cat $DNSMASQ_HOSTS) |
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CONF_LEASES=$(join $'\n' $CONF_LEASES | sort -u) |
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ALIVE_LEASES=( $MAC,$IP ) |
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|
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for i in $CONF_LEASES |
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do |
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LEASE_MAC=$(echo $i | cut -d "," -f 1) |
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LEASE_IP=$(echo $i | cut -d "," -f 2) |
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if [ "$LEASE_MAC" != "$MAC" -a "$LEASE_IP" != "$IP" ] |
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then |
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ALIVE_LEASES=( ${ALIVE_LEASES[@]} $i ) |
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fi |
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done |
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|
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ALIVE_LEASES=$(echo ${ALIVE_LEASES[@]} | sort -u) |
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# Update dnsmasq configuration. |
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# |
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# Write the parameters we have collected before into the new dnsmasq |
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# configuration file. Also, write the new leases into the new dnsmasq |
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# hosts file. Finally, restart dnsmasq with the new configuration |
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# files. |
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cat > $DNSMASQ_CONF <<EOF |
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$DNSMASQ_MODE |
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dhcp-authoritative |
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dhcp-hostsfile=$DNSMASQ_HOSTS |
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dhcp-range=169.254.0.0,static,255.255.0.0 |
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except-interface=eth* |
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except-interface=lo |
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leasefile-ro |
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no-hosts |
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no-ping |
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no-resolv |
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pid-file=$DNSMASQ_PID |
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port=0 |
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strict-order |
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EOF |
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for i in $ALIVE_INTERFACES; do echo interface=$i >> $DNSMASQ_CONF; done |
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|
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echo -n > $DNSMASQ_HOSTS |
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for i in $ALIVE_LEASES; do echo $i >> $DNSMASQ_HOSTS; done |
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|
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restart_dnsmasq |