From 3cddf31eb6d2656178908f67f431429c035fd8d3 Mon Sep 17 00:00:00 2001
From: Aleix Murtra <alemurbcn@gmail.com>
Date: Thu, 19 Oct 2023 16:03:14 +0200
Subject: [PATCH] Helm Chart: Support StatefulSet PVC retention

Add new variable on the Helm chart to define the PVC retention policy for
the StatefulSet
---
 .changelog/3180.txt                           |  3 +
 .../consul/templates/server-statefulset.yaml  |  3 +
 .../consul/test/unit/server-statefulset.bats  | 67 +++++++++++++++++++
 charts/consul/values.yaml                     | 15 +++++
 4 files changed, 88 insertions(+)
 create mode 100644 .changelog/3180.txt

diff --git a/.changelog/3180.txt b/.changelog/3180.txt
new file mode 100644
index 0000000000..aee3bfb8aa
--- /dev/null
+++ b/.changelog/3180.txt
@@ -0,0 +1,3 @@
+```release-note:feature
+helm: add persistentVolumeClaimRetentionPolicy variable for managing Statefulsets PVC retain policy when deleting or downsizing the statefulset.
+```
diff --git a/charts/consul/templates/server-statefulset.yaml b/charts/consul/templates/server-statefulset.yaml
index d2785369c7..c5935f1499 100644
--- a/charts/consul/templates/server-statefulset.yaml
+++ b/charts/consul/templates/server-statefulset.yaml
@@ -44,6 +44,9 @@ spec:
     rollingUpdate:
       partition: {{ .Values.server.updatePartition }}
   {{- end }}
+  {{- if and (semverCompare ">= 1.23-0" .Capabilities.KubeVersion.Version) (.Values.server.persistentVolumeClaimRetentionPolicy) }}
+  persistentVolumeClaimRetentionPolicy: {{ toYaml .Values.server.persistentVolumeClaimRetentionPolicy | nindent 4 }}
+  {{- end }}
   selector:
     matchLabels:
       app: {{ template "consul.name" . }}
diff --git a/charts/consul/test/unit/server-statefulset.bats b/charts/consul/test/unit/server-statefulset.bats
index f4ab239aa8..895bdeb4e8 100755
--- a/charts/consul/test/unit/server-statefulset.bats
+++ b/charts/consul/test/unit/server-statefulset.bats
@@ -196,6 +196,73 @@ load _helpers
   [ "${actual}" = "foo" ]
 }
 
+#--------------------------------------------------------------------
+# persistentVolumeClaimRetentionPolicy
+
+@test "server/StatefulSet: persistentVolumeClaimRetentionPolicy not set by default when kubernetes < 1.23" {
+  cd `chart_dir`
+  local actual=$(helm template \
+      -s templates/server-statefulset.yaml  \
+      --kube-version "1.22" \
+      . | tee /dev/stderr |
+      yq -r '.spec.persistentVolumeClaimRetentionPolicy' | tee /dev/stderr)
+  [ "${actual}" = "null" ]
+}
+
+@test "server/StatefulSet: unset persistentVolumeClaimRetentionPolicy.whenDeleted when kubernetes < 1.23" {
+  cd `chart_dir`
+  local actual=$(helm template \
+      -s templates/server-statefulset.yaml  \
+      --kube-version "1.22" \
+      --set 'server.persistentVolumeClaimRetentionPolicy.whenDeleted=Delete' \
+      . | tee /dev/stderr |
+      yq -r '.spec.persistentVolumeClaimRetentionPolicy.whenDeleted' | tee /dev/stderr)
+  [ "${actual}" = "null" ]
+}
+
+@test "server/StatefulSet: unset persistentVolumeClaimRetentionPolicy.whenScaled when kubernetes < 1.23" {
+  cd `chart_dir`
+  local actual=$(helm template \
+      -s templates/server-statefulset.yaml  \
+      --kube-version "1.22" \
+      --set 'server.persistentVolumeClaimRetentionPolicy.whenScaled=Delete' \
+      . | tee /dev/stderr |
+      yq -r '.spec.persistentVolumeClaimRetentionPolicy.whenScaled' | tee /dev/stderr)
+  [ "${actual}" = "null" ]
+}
+
+@test "server/StatefulSet: persistentVolumeClaimRetentionPolicy not set by default when kubernetes >= 1.23" {
+  cd `chart_dir`
+  local actual=$(helm template \
+      -s templates/server-statefulset.yaml  \
+      --kube-version "1.23" \
+      . | tee /dev/stderr |
+      yq -r '.spec.persistentVolumeClaimRetentionPolicy' | tee /dev/stderr)
+  [ "${actual}" = "null" ]
+}
+
+@test "server/StatefulSet: can set persistentVolumeClaimRetentionPolicy.whenDeleted when kubernetes >= 1.23" {
+  cd `chart_dir`
+  local actual=$(helm template \
+      -s templates/server-statefulset.yaml  \
+      --kube-version "1.23" \
+      --set 'server.persistentVolumeClaimRetentionPolicy.whenDeleted=Delete' \
+      . | tee /dev/stderr |
+      yq -r '.spec.persistentVolumeClaimRetentionPolicy.whenDeleted' | tee /dev/stderr)
+  [ "${actual}" = "Delete" ]
+}
+
+@test "server/StatefulSet: can set persistentVolumeClaimRetentionPolicy.whenScaled when kubernetes >= 1.23" {
+  cd `chart_dir`
+  local actual=$(helm template \
+      -s templates/server-statefulset.yaml  \
+      --kube-version "1.23" \
+      --set 'server.persistentVolumeClaimRetentionPolicy.whenScaled=Delete' \
+      . | tee /dev/stderr |
+      yq -r '.spec.persistentVolumeClaimRetentionPolicy.whenScaled' | tee /dev/stderr)
+  [ "${actual}" = "Delete" ]
+}
+
 #--------------------------------------------------------------------
 # serverCert
 
diff --git a/charts/consul/values.yaml b/charts/consul/values.yaml
index c9abd21713..577d1af369 100644
--- a/charts/consul/values.yaml
+++ b/charts/consul/values.yaml
@@ -882,6 +882,21 @@ server:
   # @type: string
   storageClass: null
 
+  # The [Persistent Volume Claim (PVC) retention policy](https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/#persistentvolumeclaim-retention)
+  # controls if and how PVCs are deleted during the lifecycle of a StatefulSet.
+  # WhenDeleted specifies what happens to PVCs created from StatefulSet VolumeClaimTemplates when the StatefulSet is deleted, 
+  # and WhenScaled specifies what happens to PVCs created from StatefulSet VolumeClaimTemplates when the StatefulSet is scaled down.
+  # 
+  # Example:
+  #
+  # ```yaml
+  # persistentVolumeClaimRetentionPolicy:
+  #   whenDeleted: Retain
+  #   whenScaled: Retain
+  # ```
+  # @type: map
+  persistentVolumeClaimRetentionPolicy: null
+
   # This will enable/disable [service mesh](https://developer.hashicorp.com/consul/docs/connect). Setting this to true
   # _will not_ automatically secure pod communication, this
   # setting will only enable usage of the feature. Consul will automatically initialize