`--set` with `.dns` doesn't always seem to work

[pmalek]

Description

I use the following set of flags

'--set=.cpus = 6 | .memory = "10GiB" | .arch = "aarch64" | .vmType = "vz"  | .dns = []  | .dns += "192.168.1.250"'

Recently (with b5aa0dd) discovered that the dns setting doesn't always work as expected. I'm not sure what should be the effect of that setting but sometimes it does put 192.168.1.250 in /etc/resolv.conf and sometimes doesn't.

What should be the effect of that setting?

---

limactl -v
limactl version HEAD-b5aa0dd

[balajiv113]

@pmalek Which template are you using ??
Is it Alpine or Ubuntu ??

[neowu]

i encountered same behavior, after digging little into source code

it looks like, if vmType == VZ, then it's always using args.SlirpDNS (which is gatewayIp) to generate user-data
and bypass DNS settings in lima.yml, then output user-data like

manage_resolv_conf: true

resolv_conf:
  nameservers:
  - 192.168.5.2

not sure whether it's intended behavior.

from the source

lima/pkg/cidata/cidata.go

Line 268 in 391133d

if firstUsernetIndex != -1 || *y.VMType == limayaml.VZ {

always go into first if condition branch

	if firstUsernetIndex != -1 || *y.VMType == limayaml.VZ {
		args.DNSAddresses = append(args.DNSAddresses, args.SlirpDNS)
	} else if *y.HostResolver.Enabled {
		args.UDPDNSLocalPort = udpDNSLocalPort
		args.TCPDNSLocalPort = tcpDNSLocalPort
		args.DNSAddresses = append(args.DNSAddresses, args.SlirpDNS)
	} else if len(y.DNS) > 0 {
		for _, addr := range y.DNS {
			args.DNSAddresses = append(args.DNSAddresses, addr.String())
		}
	} else {
		args.DNSAddresses, err = osutil.DNSAddresses()
		if err != nil {
			return err
		}
	}

[balajiv113]

@neowu Yes that's the issue. Thanks for the analysis.
Willing to take it for fix ?? Or i can fix it

[neowu]

@balajiv113 I am willing to submit PR, though I haven't worked on Go project before :)

just need to make sure the expected behavior, do we always want to use DNS settings if existed, something like

	if len(y.DNS) > 0 {
		for _, addr := range y.DNS {
			args.DNSAddresses = append(args.DNSAddresses, addr.String())
		}
	} else if firstUsernetIndex != -1 || *y.VMType == limayaml.VZ {
		args.DNSAddresses = append(args.DNSAddresses, args.SlirpDNS)
	} else if *y.HostResolver.Enabled {
		args.UDPDNSLocalPort = udpDNSLocalPort
		args.TCPDNSLocalPort = tcpDNSLocalPort
		args.DNSAddresses = append(args.DNSAddresses, args.SlirpDNS)
	} else {
		args.DNSAddresses, err = osutil.DNSAddresses()
		if err != nil {
			return err
		}
	}

[balajiv113]

Fixed as part of #1962