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@Dude4Linux
Last active Jul 21, 2016
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Test dnsmasq with LXC containers
#!/bin/bash
#
# test-dnsmasq
#
app="wordpress"
container="${app}-container"
domain="${app}.local.lxc"
LEASES="/var/lib/misc/dnsmasq.leases"
release_lease() {
local name=$1
# release dnsmasq lease, if any before creating new container
container_mac=$(grep "\s${name}\s" ${LEASES} | awk '{print $2}')
container_ip=$( grep "\s${name}\s" ${LEASES} | awk '{print $3}')
dhcp_release natbr0 ${container_ip} ${container_mac}
}
wait_for_host() {
# wait for host name resolution
# it does not mean that host is up
local hostname="$1"
local retries="${2:-10}"
local delay="${3:-3}"
for (( i=1; i<=${retries}; i++ )); do
host ${hostname} > /dev/null && return 0;
sleep ${delay}
done
return 1;
}
# main
echo "Starting Test: $(host ${container})"
lxc-create -q -n ${container} -t turnkey -- ${app} -i ~/inithooks.conf
echo "Container created: $(host ${container})"
lxc-start -d -n ${container}
wait_for_host ${container}
echo "Container started: $(host -W30 ${container})"
sleep 5;
echo "Container started+5: $(host ${container})"
sleep 5;
echo "Container started+10: $(host ${container})"
lxc-stop -n ${container}
echo "Container stopped: $(host ${container})"
lxc-destroy -n ${container}
echo "Container destroyed: $(host ${container})"
release_lease ${container}
echo "dnsmasq lease released: $(host ${container})"
service dnsmasq reload
echo "dnsmasq reloaded: $(host ${container})"
# end
@Dude4Linux
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Dude4Linux commented Dec 13, 2015

This script was used to demonstrate the interaction between dnsmasq and LXC when a container is created, started and then destroyed. Uncomment the subroutine calls to observe the effect of wait_for_host and release_lease. These subroutines were incorporated into nginx-proxy and lxc-turnkey template. Since there is not yet a hook for lxc-destroy, we do the next best thing and release any old leases before re-creating a container using the same name.

@Dude4Linux
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Dude4Linux commented Dec 15, 2015

Corrected a mistake pointed out by Anton and clarified that we're using the default inithooks.conf.

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