feat(ansible): add idempotency checks to skip already-upgraded control plane nodes

ansible/playbooks/upgrade_k3s_aerodrome.yml

@@ -23,12 +23,14 @@
         curl -sfL "https://github.com/k3s-io/k3s/releases/download/${ENCODED_VER}/k3s-arm64" -o /usr/local/bin/k3s.new
         chmod +x /usr/local/bin/k3s.new
         mv /usr/local/bin/k3s.new /usr/local/bin/k3s
+      when: target_k3s_version not in pre_k3s_ver.stdout
       register: k3s_download
 
     - name: Restart K3s systemd service
       ansible.builtin.systemd:
         name: k3s
         state: restarted
+      when: target_k3s_version not in pre_k3s_ver.stdout
 
     - name: Wait for K3s systemd unit to report active
       ansible.builtin.command: systemctl is-active k3s
@@ -37,6 +39,7 @@
       retries: 20
       delay: 4
       changed_when: false
+      when: target_k3s_version not in pre_k3s_ver.stdout
 
     - name: Wait for upgraded node to report Ready in Kubernetes
       ansible.builtin.command: kubectl get node {{ inventory_hostname }} -o jsonpath='{.status.conditions[?(@.type=="Ready")].status}'
@@ -46,6 +49,7 @@
       retries: 30
       delay: 5
       changed_when: false
+      when: target_k3s_version not in pre_k3s_ver.stdout
 
     - name: Query post-upgrade K3s version
       ansible.builtin.command: k3s --version
@@ -57,8 +61,9 @@
         that:
           - target_k3s_version in post_k3s_ver.stdout
         fail_msg: "Post-upgrade version does not match target {{ target_k3s_version }}"
-        success_msg: "{{ inventory_hostname }} successfully upgraded to {{ target_k3s_version }}"
+        success_msg: "{{ inventory_hostname }} is verified on {{ target_k3s_version }}"
 
     - name: Settle etcd cluster state
       ansible.builtin.pause:
         seconds: 10
+      when: target_k3s_version not in pre_k3s_ver.stdout