fix: make Ansible reruns faster and idempotent

ansible/roles/k3s-agent/tasks/main.yml

@@ -1,18 +1,29 @@
 ---
-- name: Check if k3s agent is already installed
+- name: Check if k3s agent service exists
   stat:
-    path: /usr/local/bin/k3s-agent
-  register: k3s_agent_binary
+    path: /etc/systemd/system/k3s-agent.service
+  register: k3s_agent_service
+
+- name: Check k3s agent service state
+  command: systemctl is-active k3s-agent
+  register: k3s_agent_service_state
+  changed_when: false
+  failed_when: false
+  when: k3s_agent_service.stat.exists
+
+- name: Determine whether k3s agent install is needed
+  set_fact:
+    k3s_agent_install_needed: "{{ (not k3s_agent_service.stat.exists) or ((k3s_agent_service_state.stdout | default('')) != 'active') }}"
 
 - name: Download k3s install script
   get_url:
     url: https://get.k3s.io
     dest: /tmp/install-k3s.sh
     mode: "0755"
-  when: not k3s_agent_binary.stat.exists
+  when: k3s_agent_install_needed
 
 - name: Install k3s agent
-  when: not k3s_agent_binary.stat.exists
+  when: k3s_agent_install_needed
   block:
     - name: Run k3s agent install
       environment: