From 4ae1856b5c18625fa8152cfdada3acabfc058fda Mon Sep 17 00:00:00 2001
From: Fabrice <fabrice@arista.com>
Date: Tue, 30 Nov 2021 09:46:29 -0800
Subject: [PATCH] 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>
---
 .../290-returns-diff-in-check-mode.yaml       |  2 +
 .../roles/helm/tasks/tests_helm_diff.yml      | 42 +++++++++++++++++++
 plugins/modules/helm.py                       |  6 ++-
 3 files changed, 48 insertions(+), 2 deletions(-)
 create mode 100644 changelogs/fragments/290-returns-diff-in-check-mode.yaml

diff --git a/changelogs/fragments/290-returns-diff-in-check-mode.yaml b/changelogs/fragments/290-returns-diff-in-check-mode.yaml
new file mode 100644
index 00000000..fe2a51d6
--- /dev/null
+++ b/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.
diff --git a/molecule/default/roles/helm/tasks/tests_helm_diff.yml b/molecule/default/roles/helm/tasks/tests_helm_diff.yml
index 5b4ec579..3191e227 100644
--- a/molecule/default/roles/helm/tasks/tests_helm_diff.yml
+++ b/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 }}"
diff --git a/plugins/modules/helm.py b/plugins/modules/helm.py
index 7e9a7067..4265ef2c 100644
--- a/plugins/modules/helm.py
+++ b/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. "