How do I set register a variable to persist between plays in ansible?

Question

I have an ansible playbook, where I\'d like a variable I register on one machine to be available on another.

In my case, I\'d like to run a command on localhos

Answer 1

Use a dummy host and its variables

For example to pass K8S token and hash from the master to the workers.

On master

- name: "Cluster token"
  shell: kubeadm token list | cut -d ' ' -f1 | sed -n '2p'
  register: K8S_TOKEN

- name: "CA Hash"
  shell: openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | openssl dgst -sha256 -hex | sed 's/^.* //'
  register: K8S_MASTER_CA_HASH

- name: "Add K8S Token and Hash to dummy host"
  add_host:
    name:   "K8S_TOKEN_HOLDER"
    token:  "{{ K8S_TOKEN.stdout }}"
    hash:   "{{ K8S_MASTER_CA_HASH.stdout }}"

- name:
  debug:
    msg: "[Master] K8S_TOKEN_HOLDER K8S token is {{ hostvars['K8S_TOKEN_HOLDER']['token'] }}"

- name:
  debug:
    msg: "[Master] K8S_TOKEN_HOLDER K8S Hash is  {{ hostvars['K8S_TOKEN_HOLDER']['hash'] }}"

On worker

- name:
  debug:
    msg: "[Worker] K8S_TOKEN_HOLDER K8S token is {{ hostvars['K8S_TOKEN_HOLDER']['token'] }}"

- name:
  debug:
    msg: "[Worker] K8S_TOKEN_HOLDER K8S Hash is  {{ hostvars['K8S_TOKEN_HOLDER']['hash'] }}"

- name: "Kubeadmn join"
  shell: >
    kubeadm join --token={{ hostvars['K8S_TOKEN_HOLDER']['token'] }}
    --discovery-token-ca-cert-hash sha256:{{ hostvars['K8S_TOKEN_HOLDER']['hash'] }}
    {{K8S_MASTER_NODE_IP}}:{{K8S_API_SERCURE_PORT}}