QEMU Get Guest IP

stacksofplates

QEMU has a guest agent like other hypervisors. If you have the guest agent you can get some info out of the guest directly from the host. Here's a way to get the IP address from the guest:

virsh qemu-agent-command $guest '{"execute":"guest-network-get-interfaces"}' | python -mjson.tool

This spits out some json:

{
    "return": [
        {
            "hardware-address": "00:00:00:00:00:00",
            "ip-addresses": [
                {
                    "ip-address": "127.0.0.1",
                    "ip-address-type": "ipv4",
                    "prefix": 8
                },
                {
                    "ip-address": "::1",
                    "ip-address-type": "ipv6",
                    "prefix": 128
                }
            ],
            "name": "lo"
        },
        {
            "hardware-address": "52:54:00:1b:3a:ba",
            "ip-addresses": [
                {
                    "ip-address": "10.1.30.6",
                    "ip-address-type": "ipv4",
                    "prefix": 24
                },
                {
                    "ip-address": "fe80::5054:ff:fe1b:3aba",
                    "ip-address-type": "ipv6",
                    "prefix": 64
                }
            ],
            "name": "eth0"
        }
    ]
}

stacksofplates

After looking around, you don't have to pass commands to QEMU directly. You can do the same thing using virsh and the domifaddr command:

[jhooks@kvm ~]$ sudo virsh domifaddr gluster1 --source agent
 Name       MAC address          Protocol     Address
-------------------------------------------------------------------------------
 lo         00:00:00:00:00:00    ipv4         127.0.0.1/8
 -          -                    ipv6         ::1/128
 eth0       52:54:00:50:d0:77    ipv4         10.1.30.220/24
 -          -                    ipv6         fe80::5054:ff:fe50:d077/64

This is a little nicer since it doesn't spit out a ton of JSON to parse through. However, this means the last few hours I've spent trying to get Ansible to read just the one hardware address was for nothing.

dafyre

But you learned something along the way.