Register docker container hostnames in libvirt network.

docker_register_libvirt_hostname.sh

#!/bin/sh

# adapted from https://gist.github.com/freshjones/b0713263033df8cc9f44

docker events --filter 'event=start' --filter 'event=die' | while read e

do
    timestamp=`echo $e | cut -d " " -f 1`
    object=`echo $e | cut -d " " -f 2`
    event=`echo $e | cut -d " " -f 3`
    container_id=`echo $e | cut -d " " -f 4`

    echo $e

    info=`docker inspect --format='{{.Name}} {{.Config.Hostname}} {{.NetworkSettings.IPAddress}}' $container_id`

    name=`echo $info | cut -d " " -f 1 | cut -d "/" -f 2`
    host=`echo $info | cut -d " " -f 2`
    ipaddress=`echo $info | cut -d " " -f 3`

    case $event in
    start)
        echo Registering container on libvirt network Name: $name DNS: $host IP: $ipaddress

        sudo virsh net-update default add dns-host "<host ip='$ipaddress'><hostname>$host</hostname></host>" --live
        ;;
    die)
        echo Unregistering container on libvirt network Name: $name DNS: $host IP: $ipaddress

        sudo virsh net-update default delete dns-host "<host><hostname>$host</hostname></host>" --live
        ;;
    esac
done