DHCP - namerservers not defined to expected ones when initializing a VM.

[dcdh]

I am struggling when setting up nameservers at server boot time.

Setup

My setup is a virtual machine (CentOS8 - qemu version) managed by libvirt.

Cloud init version in CentOS8 vm

[root@services log]# cloud-init -v
/bin/cloud-init 18.5

Network setup:

<network xmlns:dnsmasq='http://libvirt.org/schemas/network/dnsmasq/1.0'>
    <name>okd_network</name>
    <bridge name="virbr1" />
    <forward mode="nat">
        <nat>
            <port start='0' end='65535'/>
        </nat>
    </forward>
    <ip address='10.0.5.1' netmask='255.255.255.0'>
        <dhcp>
            <host mac="52:54:10:00:05:57" name="services.sandbox.okd.local" ip="10.0.5.57"/>
            <host mac="52:54:10:00:05:58" name="bootstrap.sandbox.okd.local" ip="10.0.5.58"/>
            <host mac="52:54:10:00:05:59" name="control-plane-0.sandbox.okd.local" ip="10.0.5.59"/>
        </dhcp>
    </ip>
    <dnsmasq:options>
        <dnsmasq:option value="dhcp-option=option:dns-server,10.0.5.57,8.8.8.8"/>
        <dnsmasq:option value="log-dhcp"/>
    </dnsmasq:options>
</network>

By running this command under my host dhcping -s 10.0.5.1 -c 10.0.5.57 -h 52:54:10:00:05:57 I obtain this in my log journalctl -f -u libvirtd

déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 available DHCP subnet: 10.0.5.1/255.255.255.0
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 DHCPREQUEST(virbr1) 10.0.5.57 52:54:10:00:05:57
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 tags: known, virbr1
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: Ignoring domain sandbox.okd.local for DHCP host name services
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 DHCPACK(virbr1) 10.0.5.57 52:54:10:00:05:57 services
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 next server: 10.0.5.1
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 sent size:  1 option: 53 message-type  5
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 sent size:  4 option: 54 server-identifier  10.0.5.1
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 sent size:  4 option: 51 lease-time  1h
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 sent size:  4 option: 58 T1  30m
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 sent size:  4 option: 59 T2  52m30s
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 sent size:  4 option:  1 netmask  255.255.255.0
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 sent size:  4 option: 28 broadcast  10.0.5.255
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 sent size:  4 option:  3 router  10.0.5.1
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 sent size:  8 option: 12 hostname  services
déc. 25 21:46:52 linux-4.home dnsmasq-dhcp[746134]: 3159352927 sent size:  8 option:  6 dns-server  10.0.5.57, 8.8.8.8

=> the dns-server returned by the netmasq dhcp is well defined to 10.0.5.57 and 8.8.8.8.

After the VM has booted I've got this log cloud-init.log

2020-12-25 15:12:41,143 - stages.py[DEBUG]: applying net config names for {'version': 2, 'ethernets': {'eth0': {'match': {'mac_address': '52:54:10:00:05:57'}, 'addresses': ['10.0.5.57'], 'gateway4': '10.0.5.1', 'nameservers': {'addresses': ['127.0.0.1', '8.8.8.8']}}}}

IP and gateway addresses are well defined, however I expect to have 10.0.5.57 and 8.8.8.8 for nameservers.

Checking the network /etc/sysconfig/network-scripts/ifcfg-eth0 I've got this:

# Created by cloud-init on instance boot automatically, do not edit.
#
BOOTPROTO=none
DEFROUTE=yes
DEVICE=eth0
DNS1=127.0.0.1
DNS2=8.8.8.8
GATEWAY=10.0.5.1
IPADDR=10.0.5.57
NETMASK=255.255.255.0
ONBOOT=yes
TYPE=Ethernet
USERCTL=no

DNS1 and DNS2 do not match my expected value from dhcp setup.

If I check the /etc/resolv.conf content I have got :

[root@services log]# cat /etc/resolv.conf 
# Generated by NetworkManager
search sandbox.okd.local
nameserver 127.0.0.1
nameserver 8.8.8.8

Which correspond to the DNS1 and DNS2 values unwanted values.

If I ran dhclient my resolv.conf is defined with expected nameservers

[root@services log]# cat /etc/resolv.conf 
; generated by /usr/sbin/dhclient-script
nameserver 10.0.5.57
nameserver 8.8.8.8

So the dhcp is well defined.

What can I do to ensure that DNS1 and DNS2 will correspond to the nameservers defined in DHCP libvirt network setup ?

[dcdh]

I have keep using an old configuration while launching my instance. Tried again and it works. Sorry for filling that issue (which is not one).