[BUG] DNS servers offered by DHCP server are not set in PXE boot installation

[bk201]

Describe the bug The DNS servers offered by the DHCP server are not configured in the PXE boot installation time. If the Harvester configuration file is served from a server that needs name resolution, the installation will fail.

To Reproduce Steps to reproduce the behavior:

1. Create a DHCP server to offer IPs and DNS servers for PXE boot installation.
2. Perform PXE boot installation. The DNS servers are not configured correctly:

   rancher:~ # cat /etc/resolv.conf
   ### /etc/resolv.conf is a symlink to /var/run/netconfig/resolv.conf
   ### autogenerated by netconfig!
   #
   # Before you change this file manually, consider to define the
   # static DNS configuration using the following variables in the
   # /etc/sysconfig/network/config file:
   #     NETCONFIG_DNS_STATIC_SEARCHLIST
   #     NETCONFIG_DNS_STATIC_SERVERS
   #     NETCONFIG_DNS_FORWARDER
   # or disable DNS configuration updates via netconfig by setting:
   #     NETCONFIG_DNS_POLICY=''
   #
   # See also the netconfig(8) manual page and other documentation.
   #
   ### Call "netconfig update -f" to force adjusting of /etc/resolv.conf.

Expected behavior The DNS servers provided by the DHCP server should be configured in the /etc/resolv.conf file.

Support bundle

Environment:

• Harvester ISO version: v0.3.0-preview1
• Underlying Infrastructure (e.g. Baremetal with Dell PowerEdge R630): VM, Equnix.

Additional context

• The name servers are set correctly during the initramfs stage, but not configured correctly in the real root.
• This is an issue caused by the predictable interface name change. Previously, we have a configuration file /etc/sysconfig/network/ifcfg-eth0 to make interface eth0 default to DHCP mode and wicked brings up eth0 in a later stage. The DNS serves will be re-configured at that time. The file is removed in the PR.
• We also need to consider booting from another interface.
• This only affects PXE boot installation. The DNS servers are set correctly if user boots from ISO.

[guangbochen]

@guangyee can u guys please help to verify if this is fixed in the master-head.iso, thanks

[juadk]

I was impacted by this issue and now it's ok with the last master-head.iso. /etc/resolt.confis filled with the good DNS information and I'm able to download the harvester ISO and the config file using the DNS name of my webserver.