One of the most annoying thing is when the resolv.conf of your VM keeps changing because of the information sent by the DNSMASQ process. In this article, I assume that your setup has some conventions such as:
- One network per customer, with fixed_ips range with something like
10.100.$ID.0/24 - One ID (number) per tenant
First create a template file for your initial dhclient configuration file. Using a template file makes things easier to build base images.
$ sudo cp /etc/dhcp/dhclient.conf /etc/dhcp/dhclient.conf.template
Then append the following lines in /etc/dhcp/dhclient.conf.template:
supersede domain-name-servers 10.100.X.254;
supersede domain-name "template.your-super-cloud.domain";
The above example shows my fixed_ips range. You might have to edit it with your own range.
Eventually edit your /etc/rc.local with the following:
#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.
# Grab the tenant name
TENANT=$(curl -f http://169.254.169.254/latest/meta-data/hostname | cut -f 1 -d '-')
# Grab the tenant ID
ID=$(echo $TENANT | cut -c 1-2)
# Update the DHCP conf
\cp /etc/dhcp/dhclient.conf.template /etc/dhcp/dhclient.conf
sed -i s/template/$TENANT/ /etc/dhcp/dhclient.conf
sed -i s/X/$ID/ /etc/dhcp/dhclient.conf
/usr/bin/killall dhclient3
/sbin/dhclient3 -e IF_METRIC=100 -pf /var/run/dhclient.eth0.pid -lf /var/lib/dhcp/dhclient.eth0.leases -1 eth0
Enjoy!