Improve change detection for cluster bootstrap

ansible_playbooks/setup-cluster.yml

@@ -242,6 +242,7 @@
       run_once: true
       ignore_errors: true
       register: bootstrap_result
+      changed_when: bootstrap_result is succeeded
 
     - name: Save bootstrap result
       copy:
@@ -273,13 +274,15 @@
           - list
       environment:
         NOMAD_TOKEN: "{{ read_secretid.stdout }}"
-      run_once: true
       register: policies
+      run_once: true
+      changed_when: false
 
     - name: Copy policy
       copy:
         src: ../acls/nomad-anon-policy.hcl
         dest: /tmp/anonymous.policy.hcl
+      delegate_to: "{{ play_hosts[0] }}"
       run_once: true
       register: anon_policy
 
@@ -299,6 +302,18 @@
       delegate_to: "{{ play_hosts[0] }}"
       run_once: true
 
+    - name: Read scheduler config
+      command:
+        argv:
+          - nomad
+          - operator
+          - scheduler
+          - get-config
+          - -json
+      run_once: true
+      register: scheduler_config
+      changed_when: false
+
     - name: Enable service scheduler preemption
       command:
         argv:
@@ -306,12 +321,24 @@
           - operator
           - scheduler
           - set-config
-          - -preempt-system-scheduler=true
           - -preempt-service-scheduler=true
       environment:
         NOMAD_TOKEN: "{{ read_secretid.stdout }}"
-      delegate_to: "{{ play_hosts[0] }}"
       run_once: true
+      when: (scheduler_config.stdout | from_json)["SchedulerConfig"]["PreemptionConfig"]["ServiceSchedulerEnabled"] is false
+
+    - name: Enable system scheduler preemption
+      command:
+        argv:
+          - nomad
+          - operator
+          - scheduler
+          - set-config
+          - -preempt-system-scheduler=true
+      environment:
+        NOMAD_TOKEN: "{{ read_secretid.stdout }}"
+      run_once: true
+      when: (scheduler_config.stdout | from_json)["SchedulerConfig"]["PreemptionConfig"]["SystemSchedulerEnabled"] is false
 
     # - name: Set up Nomad backend and roles in Vault
     #   community.general.terraform: