OpenStack Compute (nova)

IP Doesn't Match DHCP for new Instances

Bug #1077441 reported by Kyle Brandt
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
OpenStack Compute (nova)
Invalid
High
Jian Wen
OpenStack Dashboard (Horizon)
Won't Fix
Undecided
Gabriel Hurley

Bug Description

With FlatDHCPManager, when I provision a new VM via Horizon, my router provides the Instance with an IP. However, Horizon seems to think it has a different IP. Until I manually change the IP of the instance to match what Horizon shows the ip as, networking doesn't work to and from the VM.

Host:
nova-manage network create my_flat3 --fixed_range_v4=192.168.1.0/24 --num_networks=1 --bridge=br100 --bridge_interface=eth0 --multi_host=T

# NETWORK
network_manager=nova.network.manager.FlatDHCPManager
dhcpbridge_flagfile=/etc/nova/nova.conf
dhcpbridge=/usr/bin/nova-dhcpbridge
firewall_driver=nova.virt.libvirt.firewall.IptablesFirewallDriver
force_dhcp_release=True
flat_interface=eth0
flat_network_bridge=br100
connection_type=libvirt
fixed_range=192.168.1.0/24
flat_network_dhcp_start=192.168.1.19
flat_injected=False
multi_host=True

Inside a VM:
Starting network...
udhcpc (v1.18.5) started
Sending discover...
Sending select for 192.168.1.143...
Lease of 192.168.1.143 obtained, lease time 86400
deleting routers
route: SIOCDELRT: No such process
adding dns 192.168.1.1

Michael Still (mikal)
Changed in nova:
status: New → Triaged
importance: Undecided → High
Revision history for this message
Gabriel Hurley (gabriel-hurley) wrote :

Horizon shows exactly what Nova reports via the API. Any problem here is on Nova's side of the fence.

Changed in horizon:
assignee: nobody → Gabriel Hurley (gabriel-hurley)
status: New → Won't Fix
Jian Wen (wenjianhn)
Changed in nova:
assignee: nobody → Jian Wen (wenjianhn)
Revision history for this message
Jian Wen (wenjianhn) wrote :

The VM ip 192.168.1.143 was leased from your router instead of dnsmasq on your network-node.
ebtables rules are used to protect the network from ip spoof. If the source ip of a packet
sent from a VM is not the ip dnsmasq released, it will be dropped. As a result, the networking
of the VM doesn't work.

You shouldn't let your router be the DHCP server.
Maybe you need to disable DHCP server of the router in a develop environment.

Changed in nova:
status: Triaged → Invalid
Revision history for this message
Kyle Brandt (kyle-kbrandt) wrote :

Agreed. I ended up in some weird places trying to get FlatDHCP working. I eventually discovered it was the bug I described in:

http://serverfault.com/questions/448347/instances-in-openstack-are-not-getting-dhcp-leases/448348#448348

Which was pretty nasty to find. Feel free to close this, no way it is a bug IMO. If anything, it would be a feature request (support external DHCP servers).

Revision history for this message
Jian Wen (wenjianhn) wrote :

I will fix that bug.

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