Selectively remove existing token from the environment file

If the existing token in the environment file is the same as the token
used for the playbook run, leave it in the file to avoid false changed
status from the task.

roles/k3s_agent/tasks/main.yml

@@ -35,11 +35,11 @@
         INSTALL_K3S_EXEC: "agent"
       changed_when: true
 
-- name: Delete any existing token from the environment
+- name: Delete any existing token from the environment if different from the new one
   ansible.builtin.lineinfile:
     state: absent
     path: "{{ systemd_dir }}/k3s-agent.service.env"
-    search_string: "K3S_TOKEN="
+    regexp: "^K3S_TOKEN=\\s*(?!{{ token }}\\s*$)"
 
 - name: Add the token for joining the cluster to the environment
   no_log: true # avoid logging the server token

roles/k3s_server/tasks/main.yml

@@ -86,11 +86,11 @@
         line: "{{ item }}"
       with_items: "{{ extra_service_envs }}"
 
-    - name: Delete any existing token from the environment
+    - name: Delete any existing token from the environment if different from the new one
       ansible.builtin.lineinfile:
         state: absent
         path: "{{ systemd_dir }}/k3s.service.env"
-        search_string: "K3S_TOKEN="
+        regexp: "^K3S_TOKEN=\\s*(?!{{ token }}\\s*$)"
 
     # Add the token to the environment.
     - name: Add token as an environment variable
@@ -187,11 +187,11 @@
     - (groups[server_group] | length) > 1
     - inventory_hostname != groups[server_group][0]
   block:
-    - name: Delete any existing token from the environment
+    - name: Delete any existing token from the environment if different from the new one
       ansible.builtin.lineinfile:
         state: absent
         path: "{{ systemd_dir }}/k3s.service.env"
-        search_string: "K3S_TOKEN="
+        regexp: "^K3S_TOKEN=\\s*(?!{{ token }}\\s*$)"
 
     - name: Add the token for joining the cluster to the environment
       no_log: true # avoid logging the server token