From eb7f5815272a56e3e489835d01eeed7bd21b4c32 Mon Sep 17 00:00:00 2001
From: Guilhem Moulin <guilhem@fripost.org>
Date: Tue, 29 Oct 2013 21:51:18 +0100
Subject: Use fixed IPs for the new virtual hosts.

Each new VM is attributed a fresh static IPv4 (uniqueness is guaranteed
by merely incrementing the /24), and DNS entries are added libvirt's
dnsmasq instance.
---
 virtualenv/virt | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/virtualenv/virt b/virtualenv/virt
index 46c56dc..b88d04e 100755
--- a/virtualenv/virt
+++ b/virtualenv/virt
@@ -28,6 +28,10 @@ get_XML_attribute() {
     /usr/bin/virsh dumpxml "$domain" \
     | /usr/bin/xmlstarlet sel -t -m /domain/"$object" -v @"$attribute"
 }
+add_net_section() {
+    local net="${3:-$network}" section="$1" xml="$2"
+    /usr/bin/virsh net-update "$net" add "$section" --xml "$xml" --live --config
+}
 
 doesExist() {
     /usr/bin/virsh -r list --all --name | grep -qxF "$1"
@@ -78,17 +82,37 @@ install() {
 
     # TODO: the bus should be chosen at random among sata,ide,scsi,usb
     # TODO: test EFI: http://www.linux-kvm.org/page/OVMF
+    local network=default
     /usr/bin/virt-install -q \
         --name      "$name" \
         --arch      "$ARCH" \
         --ram       128 \
         --cdrom     "$cdrom" \
         --disk      "$disk",cache=writeback,bus=sata \
-        --network   network=default \
+        --network   network=$network \
         --graphics  spice
 
+    # Attribute the next available IP. You may also want to add a domain
+    # section, e.g., <domain name='libvirt.example.org'/>, and prepend
+    # the DNS IP to /etc/resolv.conf.
+    # Cf. http://libvirt.org/formatnetwork.html
+    local mac ip
+    mac=$(get_XML_attribute "$name" devices/interface/mac address)
+    ip=$( /usr/bin/virsh net-dumpxml $network \
+        | /usr/bin/xmlstarlet sel -t -m /network/ip/dhcp/host -n -v @ip \
+        | sed '/^\s*$/d' \
+        | sort -n \
+        | tail -1 )
+    [ -n "$ip" ] || \
+    ip=$( /usr/bin/virsh net-dumpxml $network \
+        | /usr/bin/xmlstarlet sel -t -m /network/ip -v @address )
+    ip=${ip%.*}.$(( 1 + ${ip##*.} ))
+    add_net_section ip-dhcp-host "<host mac='$mac' name='$name' ip='$ip'/>"
+    add_net_section dns-host     "<host ip='$ip'><hostname>$name</hostname></host>"
+
     cat >&2 <<- EOF
-		Domain '$name' has been created. As you can see in
+		Domain '$name' has been created, and has been attributed the IP $ip.
+		As you can see in
 
 		    virsh list
 
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