Test dnsmasq with LXC containers

test-dnsmasq

#!/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

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.

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