Allow to scale to zero via helm values (#1627)

Author: jonesbusy

charts/jenkins/CHANGELOG.md

@@ -12,6 +12,10 @@ Use the following links to reference issues, PRs, and commits prior to v2.6.0.
 The changelog until v1.5.7 was auto-generated based on git commits.
 Those entries include a reference to the git commit to be able to get more details.
 
+## 5.9.3
+
+Allow to scale controller to zero replicas during maintenance scenarios.
+
 ## 5.9.2
 
 Add support for annotations on the HTTPRoute resource

charts/jenkins/Chart.yaml

@@ -2,7 +2,7 @@ apiVersion: v2
 name: jenkins
 type: application
 home: https://www.jenkins.io/
-version: 5.9.2
+version: 5.9.3
 appVersion: 2.541.2
 description: >
   Jenkins - Build great things at any scale! As the leading open source automation server, Jenkins provides over 2000 plugins to support building, deploying and automating any project.

charts/jenkins/VALUES.md

@@ -714,3 +714,11 @@ Create the HTTP port for interacting with the controller
     {{- end }}
 
 {{- end -}}
+
+{{- define "controller.replicas" -}}
+{{- $replicas := int (default 1 .Values.controller.replicas) -}}
+{{- if or (lt $replicas 0) (gt $replicas 1) -}}
+{{- fail "controller.replicas must be 0 or 1" -}}
+{{- end -}}
+{{- .Values.controller.replicas -}}
+{{- end -}}

charts/jenkins/templates/_helpers.tpl

@@ -18,7 +18,7 @@ metadata:
   {{- end }}
 spec:
   serviceName: {{ template "jenkins.fullname" . }}
-  replicas: 1
+  replicas: {{ include "controller.replicas" . }}
   selector:
     matchLabels:
       "app.kubernetes.io/component": "{{ .Values.controller.componentName }}"

charts/jenkins/templates/jenkins-controller-statefulset.yaml

@@ -840,3 +840,30 @@ tests:
       renderHelmLabels: false
     asserts:
       - matchSnapshot: {}
+  - it: fails when replicas is greater than 1
+    template: jenkins-controller-statefulset.yaml
+    set:
+      controller:
+        replicas: 2
+    asserts:
+      - failedTemplate:
+          errorPattern:
+            'controller.replicas must be 0 or 1'
+  - it: allow to scale to 0 replicas
+    template: jenkins-controller-statefulset.yaml
+    set:
+      controller:
+        replicas: 0
+    asserts:
+      - equal:
+          path: spec.replicas
+          value: 0
+  - it: allow to scale to 1 replicas
+    template: jenkins-controller-statefulset.yaml
+    set:
+      controller:
+        replicas: 1
+    asserts:
+      - equal:
+          path: spec.replicas
+          value: 1

charts/jenkins/unittests/jenkins-controller-statefulset-test.yaml

@@ -51,6 +51,10 @@ controller:
     tagLabel: jdk21
     # -- Controller image pull policy
     pullPolicy: "Always"
+
+  # -- Number of replicas. Max 1. Can be set to 0 for maintenance scenarios.
+  replicas: 1
+
   # -- Controller image pull secret
   imagePullSecretName:
   # -- Lifecycle specification for controller-container