Return diff in helm check mode (#290)

Return diff in helm check mode

When the helm module is executed in check mode with the helm diff plugin
installed, it now returns the diff.
SUMMARY
When the helm module is executed in check mode with the helm diff plugin
installed, it now returns the diff.
COMPONENT NAME
helm
ADDITIONAL INFORMATION

Reviewed-by: Abhijeet Kasurde <None>
Reviewed-by: Fabrice <None>
Reviewed-by: Mike Graves <mgraves@redhat.com>
Reviewed-by: None <None>

changelogs/fragments/290-returns-diff-in-check-mode.yaml

@@ -0,0 +1,2 @@
+minor_changes:
+  - helm - when ansible is executed in check mode, return the diff between what's deployed and what will be deployed.

molecule/default/roles/helm/tasks/tests_helm_diff.yml

@@ -40,6 +40,33 @@
           data:
             foo: {{ .Values.foo | default "bar" }}
 
+    - name: Test helm diff in check mode
+      helm:
+        binary_path: "{{ helm_binary }}"
+        name: test-chart
+        namespace: "{{ helm_namespace }}"
+        chart_ref: "{{ test_chart_ref }}"
+      check_mode: yes
+      diff: yes
+      register: diff_result
+
+    - name: Check if helm diff check is correct
+      vars:
+        expected: "\u001b[0;33mhelm, test-chart-another-configmap, ConfigMap (v1) has been added:\u001b[0m\n\
+          \u001b[0;31m- \u001b[0m\n\
+          \u001b[0;32m+ # Source: test-chart/templates/anothermap.yaml\u001b[0m\n\
+          \u001b[0;32m+ # BEGIN ANSIBLE MANAGED BLOCK\u001b[0m\n\
+          \u001b[0;32m+ apiVersion: v1\u001b[0m\n\
+          \u001b[0;32m+ kind: ConfigMap\u001b[0m\n\
+          \u001b[0;32m+ metadata:\u001b[0m\n\
+          \u001b[0;32m+   name: test-chart-another-configmap\u001b[0m\n\
+          \u001b[0;32m+ data:\u001b[0m\n\
+          \u001b[0;32m+   foo: bar\u001b[0m\n\
+          \u001b[0;32m+ # END ANSIBLE MANAGED BLOCK\u001b[0m"
+      assert:
+        that:
+          - expected == diff_result.diff.prepared
+
     - name: Upgrade local chart with modifications
       helm:
         binary_path: "{{ helm_binary }}"
@@ -52,6 +79,21 @@
         that:
           - install is changed
 
+    - name: No diff in check mode when no change
+      helm:
+        binary_path: "{{ helm_binary }}"
+        name: test-chart
+        namespace: "{{ helm_namespace }}"
+        chart_ref: "{{ test_chart_ref }}"
+      check_mode: yes
+      diff: yes
+      register: diff_result
+
+    - name: Check if no diff in check mode when no change
+      assert:
+        that:
+          - '"diff" not in diff_result'
+
     - name: Upgrade modified local chart idempotency check
       helm:
         binary_path: "{{ helm_binary }}"

plugins/modules/helm.py

@@ -537,7 +537,7 @@ def helmdiff_check(
             cmd += " -f=" + values_file
 
     rc, out, err = run_helm(module, cmd)
-    return len(out.strip()) > 0
+    return (len(out.strip()) > 0, out.strip())
 
 
 def default_check(release_status, chart_info, values=None, values_files=None):
@@ -725,7 +725,7 @@ def main():
         else:
 
             if has_plugin(helm_cmd_common, "diff") and not chart_repo_url:
-                would_change = helmdiff_check(
+                (would_change, prepared) = helmdiff_check(
                     module,
                     helm_cmd_common,
                     release_name,
@@ -735,6 +735,8 @@ def main():
                     chart_version,
                     replace,
                 )
+                if would_change and module._diff:
+                    opt_result["diff"] = {"prepared": prepared}
             else:
                 module.warn(
                     "The default idempotency check can fail to report changes in certain cases. "