Re: [libvirt] Making DHCP leases available to local DNS server through dnsmasq
On 06/16/2017 12:21 PM, jean-christophe manciot wrote:
Yes, except that it *does not work*. As you can see below,
libnss-libvirt
is installed and configured, but the VM "KVM-Ubuntu-GNS3-Server-17.04" is
not reachable through its DNS name.
libvirt-nss is not for translating DNS names, rather than libvirt guest
names. That is,
# virsh start myAwesomeDomain
# ssh myAwesomeDomain
# apt-cache policy libnss-libvirt
libnss-libvirt:
Installed: 3.0.0-4
...
# cat /etc/nsswitch.conf
passwd: compat
group: compat
shadow: compat
hosts: files libvirt libvirt_guest mdns4_minimal [NOTFOUND=return] resolve
[!UNAVAIL=return] dns
networks: files
protocols: db files
services: db files
ethers: db files
rpc: db files
netgroup: nis
# systemctl status libvirtd
● libvirtd.service - Virtualization daemon
Loaded: loaded (/lib/systemd/system/libvirtd.service; enabled; vendor
preset: enabled)
Active: active (running) since Fri 2017-06-16 11:44:59 CEST; 11min ago
Docs: man:libvirtd(8)
http://libvirt.org
Main PID: 9448 (libvirtd)
CPU: 1.790s
CGroup: /system.slice/libvirtd.service
├─ 5556 /usr/sbin/dnsmasq
--conf-file=/var/lib/libvirt/dnsmasq/virtual-mgt-5.conf --leasefile-ro
--dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper
├─ 5557 /usr/sbin/dnsmasq
--conf-file=/var/lib/libvirt/dnsmasq/virtual-mgt-5.conf --leasefile-ro
--dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper
...
├─ 8805 /usr/sbin/dnsmasq
--conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro
--dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper
├─ 8806 /usr/sbin/dnsmasq
--conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro
--dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper
├─ 9448 /usr/sbin/libvirtd
└─15116 qemu-system-x86_64 -enable-kvm -name
guest=KVM-Ubuntu-GNS3-Server-17.04,debug-threads=on -S -object
secret,id=masterKey0,format=raw,file=/var/lib/libvirt/
...
Jun 16 11:55:14 samsung-ubuntu dnsmasq-dhcp[8805]: DHCPREQUEST(virbr0)
192.168.122.124 52:54:00:03:9f:9f
Jun 16 11:55:14 samsung-ubuntu dnsmasq-dhcp[8805]: DHCPACK(virbr0)
192.168.122.124 52:54:00:03:9f:9f KVM-Ubuntu-GNS3-Server-17
# ping KVM-Ubuntu-GNS3-Server-17.04
ping: KVM-Ubuntu-GNS3-Server-17.04: Name or service not known
# ping KVM-Ubuntu-GNS3-Server-17.04.actionmystique.net
ping: KVM-Ubuntu-GNS3-Server-17.04.actionmystique.net: Name or service not
known
# ping 192.168.122.124
PING 192.168.122.124 (192.168.122.124) 56(84) bytes of data.
64 bytes from 192.168.122.124: icmp_seq=1 ttl=64 time=0.181 ms
64 bytes from 192.168.122.124: icmp_seq=2 ttl=64 time=0.165 ms
This suggests your DNS server might be misconfigured. Does it have a
record for the guest you're running?
A few possible explanations for that issue are:
- something is not configured correctly
- there is an incompatibility with NetworkManager
- there is a bug with libnss-libvirt
That's possible. Can you see the guest in:
/var/lib/libvirt/dnsmasq/virbr0.{macs,status}
That's where the nss module gets translations from. Also, looks like
you're using 3.0.0 release. You need to restart the network after you've
set up the NSS module. The decision whether to create those files is
made when libvirt starts a network. Only in 3.3.0 release we're making
that decision more frequently and thus the restart is not needed.
virsh net-destroy virtual-mgt-5
virsh net-start virtual-mgt-5
Michal