Unable to get group ipv4 address in ansible with template

Question

I'm trying to enumerate my eth0 address (set to default, because I read somewhere that eth0 is not always available..). In my template I attempt calling it from the group like so...

[Unit]
Description=Kubernetes Kube Proxy
Documentation=https://github.com/GoogleCloudPlatform/kubernetes

[Service]
ExecStart=/usr/bin/kube-proxy \
  --master=https://{{ groups[controller][0]['ansible_default_ipv4']['address'] }}:6443 \
  --kubeconfig=/var/lib/kubelet/kubeconfig \
  --proxy-mode=iptables \
  --v=2

Restart=on-failure
RestartSec=5

[Install]
WantedBy=multi-user.target

This seem like it should be available as when I dump with -debug var=groups I get....

[18.234.92.196] => {
    "groups": {

      ......

        "controller": [
            "54.86.253.135",
            "52.205.43.24",
            "54.210.213.10"
        ],
        "controller.0": [
            "54.86.253.135"
        ],
        "controller.1": [
            "52.205.43.24"
        ],
        "controller.2": [
            "54.210.213.10"
        ],

        ......

        "name_controller-0": [
            "54.86.253.135"
        ],
        "name_controller-1": [
            "52.205.43.24"
        ],
        "name_controller-2": [
            "54.210.213.10"
        ],

        ......

    }
}

Weirdly when I try debugging with var=groups[controller] I get ...

TASK [worker : debug] *******************************************************************************************************************************************
ok: [34.207.172.100] => {
    "groups[controller]": "VARIABLE IS NOT DEFINED!: 'controller' is undefined"
}

.....

TASK [worker : Add Kubelet configuration] ***********************************************************************************************************************
fatal: [34.207.172.100]: FAILED! => {"changed": false, "msg": "AnsibleUndefinedVariable: 'controller' is undefined"}

What am I missing here?

Answer 1

Figured it out, needed to specify the IP via groups first and use that as an index.

Also, ansible_default_ipv4 does not seem to exist, so swapped to public_ip which is the same thing.

- name: Print hostvars
  debug:
    msg: "{{ hostvars[groups.controller.0].public_ip }}"