How to determine host IP address from inside the VM?

[jandubois]

Now, I know the host IP is always 192.168.5.2, so I can just hard-code it.

But I would prefer to dynamically determine it from the VM configuration. With qemu I would fetch it from the default route:

$ lima ip route | grep 'default via'
default via 192.168.5.2 dev eth0 proto dhcp src 192.168.5.15 metric 100

But when using VZ with gvisor-tap, it uses the SlirpDNS as the gateway address:

$ lima ip route | grep 'default via'
default via 192.168.5.3 dev eth0 proto dhcp src 192.168.5.1 metric 100

So how can I determine the actual host address to call services from the host?

@balajiv113 Any suggestions?

[jandubois]

I just realized that I already hard-code 192.168.5.15 for the guest address, so this question is just idle curiosity if this is all as-expected. I'm going to hard-code the host address as well. 😄

[balajiv113]

Logically in route there shouldn't be any difference. Looks like some bug there. Will check and update you shortly.

PS: Just noticed the bug the guest ip 192.168.5.15 is not valid for vz driver

[jandubois]

Is there a way to get VZ to use 192.168.5.15 for the guest IP? I actually care more about this than being able to parse the default route for the gateway address, as the fixed IP is the same for QEMU and VZ.

There is a comment about VZ using the DNS address as the gateway address, but I don't understand why this is the case:

lima/pkg/networks/usernet/gvproxy.go

Line 45 in fedacd2

// - DNS is equivalent to GatewayIP

[balajiv113]

We should be able to use 192.168.5.15 for vz under default network. Need to do some changes

DNS address as the gateway address

The confusion is due to how gvisor-tap-vsock supports slirp and we using our qemu variable for the same

[balajiv113]

Fixed the IP #1612

I will also change the DNS and Gateway mismatch as part of #1551