fix(elasticsearch): make cluster-settings robust to per-block check_mode

molecule/elasticsearch_no-security/converge.yml

@@ -17,3 +17,31 @@
     - name: Include Elasticsearch
       ansible.builtin.include_role:
         name: oddly.elasticstack.elasticsearch
+
+# Coverage for the `not ansible_check_mode` guards #154 added to the
+# `Start Elasticsearch` and `Handle cluster setup without security`
+# tasks/blocks, plus the `check_mode: false` shield this PR adds to
+# the cluster-settings URI. Re-running the role with check_mode: true
+# on the outer block previously exploded on the `.json` reference in
+# elasticsearch-cluster-settings.yml because the URI honoured the
+# check-mode override and returned without a body.
+- name: "Re-include ES role in check mode (regression cover for #154)"
+  hosts: all
+  vars:
+    elasticsearch_security: false
+    elasticstack_security: false
+    elasticsearch_heap: "1"
+    elasticstack_release: "{{ lookup('env', 'ELASTIC_RELEASE') | default('9', true) | int }}"
+    elasticstack_no_log: false
+    elasticstack_elasticsearch_group_name: elasticsearchXYZ
+  tasks:
+    - name: Reset shared role import guard for re-run
+      ansible.builtin.set_fact:
+        _elasticstack_role_imported: false
+
+    - name: Wrap the re-include so check_mode propagates
+      check_mode: true
+      block:
+        - name: Re-include Elasticsearch in check mode
+          ansible.builtin.include_role:
+            name: oddly.elasticstack.elasticsearch

roles/elasticsearch/tasks/elasticsearch-cluster-settings.yml

@@ -25,13 +25,19 @@
         validate_certs: "{{ elasticsearch_validate_api_certs }}"
         return_content: true
       register: _elasticsearch_current_cluster_settings
+      # The uri module honours check_mode inherited from a block/task-level
+      # override even when the play itself is not in --check, and returns
+      # without hitting the endpoint. `.json` is then missing on the
+      # registered result; guard the downstream compare so a per-block
+      # check_mode caller doesn't crash us.
+      check_mode: false
       no_log: "{{ elasticstack_no_log }}"
 
     - name: elasticsearch-cluster-settings | Check if settings already match
       ansible.builtin.set_fact:
         _elasticsearch_cluster_settings_changed: "{{ _needs_update | trim }}"
       vars:
-        _current: "{{ _elasticsearch_current_cluster_settings.json.persistent }}"
+        _current: "{{ (_elasticsearch_current_cluster_settings.json | default({})).persistent | default({}) }}"
         _needs_update: >-
           {% set ns = namespace(changed=false) %}
           {% for key, value in _elasticsearch_effective_cluster_settings.items() %}