From 4e8f6d1923782e7aef863441f7c1434ca1029164 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?L=C3=A9na=C3=AFc=20Huard?= <lhuard@amadeus.com>
Date: Wed, 20 May 2015 13:26:04 +0200
Subject: =?UTF-8?q?[libvirt=20cluster]=20Use=20net-dhcp-leases=20to=20find?=
 =?UTF-8?q?=20VMs=E2=80=99=20IPs?=
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Query libvirt’s DHCP leases rather than inspecting the host’s ARP cache
to find the VMs’ IPs.
---
 inventory/libvirt/hosts/libvirt_generic.py         | 26 ++++++----------------
 .../openshift-cluster/tasks/launch_instances.yml   | 12 +++-------
 2 files changed, 10 insertions(+), 28 deletions(-)

diff --git a/inventory/libvirt/hosts/libvirt_generic.py b/inventory/libvirt/hosts/libvirt_generic.py
index 4652f112e..d1e1069f9 100755
--- a/inventory/libvirt/hosts/libvirt_generic.py
+++ b/inventory/libvirt/hosts/libvirt_generic.py
@@ -113,8 +113,6 @@ class LibvirtInventory(object):
             print "Failed to list domains for connection %s" % libvirt_uri
             sys.exit(1)
 
-        arp_entries = self.parse_arp_entries()
-
         for domain in domains:
             hostvars = dict(libvirt_name=domain.name(),
                             libvirt_id=domain.ID(),
@@ -140,11 +138,13 @@ class LibvirtInventory(object):
             # interface types other than 'network'
             interface = root.find("./devices/interface[@type='network']")
             if interface is not None:
-                mac_elem = interface.find('mac')
-                if mac_elem is not None:
-                    mac = mac_elem.get('address')
-                    if mac in arp_entries:
-                        ip_address = arp_entries[mac]['ip_address']
+                source_elem = interface.find('source')
+                mac_elem    = interface.find('mac')
+                if source_elem is not None and \
+                   mac_elem    is not None:
+                    dhcp_leases = conn.networkLookupByName(source_elem.get('network')).DHCPLeases(mac_elem.get('address'))
+                    if len(dhcp_leases) > 0:
+                        ip_address = dhcp_leases[0]['ipaddr']
                         hostvars['ansible_ssh_host'] = ip_address
                         hostvars['libvirt_ip_address'] = ip_address
 
@@ -152,18 +152,6 @@ class LibvirtInventory(object):
 
         return inventory
 
-    def parse_arp_entries(self):
-        arp_entries = dict()
-        with open('/proc/net/arp', 'r') as f:
-            # throw away the header
-            f.readline()
-
-            for line in f:
-                ip_address, _, _, mac, _, device = line.strip().split()
-                arp_entries[mac] = dict(ip_address=ip_address, device=device)
-
-        return arp_entries
-
     def push(self, my_dict, key, element):
         if key in my_dict:
             my_dict[key].append(element)
diff --git a/playbooks/libvirt/openshift-cluster/tasks/launch_instances.yml b/playbooks/libvirt/openshift-cluster/tasks/launch_instances.yml
index 359d0b2f3..8bf1e84ee 100644
--- a/playbooks/libvirt/openshift-cluster/tasks/launch_instances.yml
+++ b/playbooks/libvirt/openshift-cluster/tasks/launch_instances.yml
@@ -58,23 +58,17 @@
     uri: '{{ libvirt_uri }}'
   with_items: instances
 
-- name: Collect MAC addresses of the VMs
-  shell: 'virsh -c {{ libvirt_uri }} dumpxml {{ item }} | xmllint --xpath "string(//domain/devices/interface/mac/@address)" -'
-  register: scratch_mac
-  with_items: instances
-
 - name: Wait for the VMs to get an IP
-  command: "egrep -c '{{ scratch_mac.results | oo_collect('stdout') | join('|') }}' /proc/net/arp"
-  ignore_errors: yes
+  shell: 'virsh net-dhcp-leases openshift-ansible | egrep -c ''{{ instances | join("|") }}'''
   register: nb_allocated_ips
   until: nb_allocated_ips.stdout == '{{ instances | length }}'
   retries: 30
   delay: 1
 
 - name: Collect IP addresses of the VMs
-  shell: "awk '/{{ item.stdout }}/ {print $1}' /proc/net/arp"
+  shell: 'virsh net-dhcp-leases openshift-ansible | awk ''$6 == "{{ item }}" {gsub(/\/.*/, "", $5); print $5}'''
   register: scratch_ip
-  with_items: scratch_mac.results
+  with_items: instances
 
 - set_fact:
     ips: "{{ scratch_ip.results | oo_collect('stdout') }}"
-- 
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