From ba9a6e37629b6e4ddbffc13ee8fdde82c53a3a98 Mon Sep 17 00:00:00 2001
From: Scott Rigby <scott@r6by.com>
Date: Tue, 8 Jul 2025 16:18:20 -0400
Subject: [PATCH] Minimum Helm version pattern

Signed-off-by: Scott Rigby <scott@r6by.com>
---
 patterns/min-helm-version/README.md           | 39 +++++++++++++++++++
 patterns/min-helm-version/mychart/Chart.yaml  |  5 +++
 .../mychart/templates/_helpers.tpl            |  8 ++++
 .../mychart/templates/secret.yaml             |  7 ++++
 4 files changed, 59 insertions(+)
 create mode 100644 patterns/min-helm-version/README.md
 create mode 100644 patterns/min-helm-version/mychart/Chart.yaml
 create mode 100644 patterns/min-helm-version/mychart/templates/_helpers.tpl
 create mode 100644 patterns/min-helm-version/mychart/templates/secret.yaml

diff --git a/patterns/min-helm-version/README.md b/patterns/min-helm-version/README.md
new file mode 100644
index 00000000..62a16f7f
--- /dev/null
+++ b/patterns/min-helm-version/README.md
@@ -0,0 +1,39 @@
+# Define the minimum Helm version for a chart
+
+The [mychart](./mychart/) chart contains a simple pattern that you can use to enforce a minimum version of the Helm client for any chart.
+
+1. Add `annotations.minimumHelmVersion` to your `Chart.yaml`. For example:
+
+    ```yaml
+    apiVersion: v2
+    name: mychart
+    version: 0.1.0
+    annotations:
+      minimumHelmVersion: 3.18.2
+    ```
+    _See [mychart/Chart.yaml](./mychart/Chart.yaml)._
+1. Add a helper function to your chart's `templates/_helpers.tpl` file, like the `mychart.validateHelmVersion` function below. Replace `mychart` with the name of your chart.
+
+    ```tpl
+    {{- define "mychart.validateHelmVersion" -}}
+      {{- $minVersion := .Chart.Annotations.minimumHelmVersion }}
+      {{- $helmVersion := trimPrefix "v" .Capabilities.HelmVersion.Version }}
+      {{- if lt $helmVersion $minVersion }}
+        {{- $message := printf "\n\nThis chart requires a minimum version of Helm %s. Please upgrade your Helm version." $minVersion }}
+        {{- fail $message }}
+      {{- end }}
+    {{- end }}
+    ```
+    _See [mychart/templates/_helpers.tpl](./mychart/templates/_helpers.tpl)._
+1. Include your helper function at the top of any template. Make sure this include statement is outside of any rendering conditional logic if you want to always enfore the minimum Helm version.
+
+    ```yaml
+    {{- include "mychart.validateHelmVersion" . }}
+    apiVersion: v1
+    kind: Secret
+    metadata:
+      name: mysecret
+    data:
+      foo: YmFyCg==
+    ```
+    _See [mychart/templates/secret.yaml](./mychart/templates/secret.yaml)._
diff --git a/patterns/min-helm-version/mychart/Chart.yaml b/patterns/min-helm-version/mychart/Chart.yaml
new file mode 100644
index 00000000..6051b0bf
--- /dev/null
+++ b/patterns/min-helm-version/mychart/Chart.yaml
@@ -0,0 +1,5 @@
+apiVersion: v2
+name: mychart
+version: 0.1.0
+annotations:
+  minimumHelmVersion: 3.18.2
diff --git a/patterns/min-helm-version/mychart/templates/_helpers.tpl b/patterns/min-helm-version/mychart/templates/_helpers.tpl
new file mode 100644
index 00000000..b6a2cb2d
--- /dev/null
+++ b/patterns/min-helm-version/mychart/templates/_helpers.tpl
@@ -0,0 +1,8 @@
+{{- define "mychart.validateHelmVersion" -}}
+  {{- $minVersion := .Chart.Annotations.minimumHelmVersion }}
+  {{- $helmVersion := trimPrefix "v" .Capabilities.HelmVersion.Version }}
+  {{- if lt $helmVersion $minVersion }}
+    {{- $message := printf "\n\nThis chart requires a minimum version of Helm %s. Please upgrade your Helm version." $minVersion }}
+    {{- fail $message }}
+  {{- end }}
+{{- end }}
diff --git a/patterns/min-helm-version/mychart/templates/secret.yaml b/patterns/min-helm-version/mychart/templates/secret.yaml
new file mode 100644
index 00000000..9b194961
--- /dev/null
+++ b/patterns/min-helm-version/mychart/templates/secret.yaml
@@ -0,0 +1,7 @@
+{{- include "mychart.validateHelmVersion" . }}
+apiVersion: v1
+kind: Secret
+metadata:
+  name: mysecret
+data:
+  foo: YmFyCg==