build(helm): handle auto-scaling volume claim access mode

Author: LouisHaftmann

install/kubernetes/github-actions-cache-server/templates/_helpers.tpl

@@ -81,6 +81,40 @@ Otherwise, auto-enable when storage driver is "filesystem" or db driver is "sqli
 {{- end -}}
 {{- end }}
 
+{{/*
+Check if multiple replicas are possible (autoscaling enabled or replicaCount > 1).
+*/}}
+{{- define "github-actions-cache-server.multipleReplicas" -}}
+{{- if or (and .Values.autoscaling.enabled (gt (.Values.autoscaling.maxReplicas | int) 1)) (gt (.Values.replicaCount | int) 1) -}}
+true
+{{- else -}}
+false
+{{- end -}}
+{{- end }}
+
+{{/*
+Effective PVC access modes.
+Automatically switches to ReadWriteMany when multiple replicas are possible
+and the filesystem storage driver is used, to prevent errors when multiple
+pods attach to the same volume.
+*/}}
+{{- define "github-actions-cache-server.pvcAccessModes" -}}
+{{- if and (eq (include "github-actions-cache-server.multipleReplicas" .) "true") (eq .Values.config.storage.driver "filesystem") -}}
+- ReadWriteMany
+{{- else -}}
+{{ toYaml .Values.persistentVolumeClaim.accessModes }}
+{{- end -}}
+{{- end }}
+
+{{/*
+Validate configuration. Fails if incompatible settings are detected.
+*/}}
+{{- define "github-actions-cache-server.validate" -}}
+{{- if and (eq .Values.config.db.driver "sqlite") (eq (include "github-actions-cache-server.multipleReplicas" .) "true") -}}
+{{- fail "SQLite database driver cannot be used with multiple replicas (autoscaling enabled or replicaCount > 1). SQLite does not support concurrent access from multiple pods. Please switch to 'postgres' or 'mysql' database driver." -}}
+{{- end -}}
+{{- end }}
+
 {{/*
 Generate environment variables from config values.
 */}}

install/kubernetes/github-actions-cache-server/templates/deployment.yaml

@@ -1,5 +1,6 @@
 {{ $name := include "github-actions-cache-server.fullname" . }}
 {{ $pvcEnabled := include "github-actions-cache-server.pvcEnabled" . }}
+{{- include "github-actions-cache-server.validate" . -}}
 ---
 apiVersion: apps/v1
 kind: Deployment

install/kubernetes/github-actions-cache-server/templates/persistentvolumeclaim.yaml

@@ -16,7 +16,7 @@ metadata:
   {{- end }}
 spec:
   accessModes:
-    {{- toYaml .Values.persistentVolumeClaim.accessModes | nindent 4 }}
+    {{- include "github-actions-cache-server.pvcAccessModes" . | nindent 4 }}
   resources:
     requests:
       storage: {{ .Values.persistentVolumeClaim.storage }}

install/kubernetes/github-actions-cache-server/values.yaml

@@ -203,10 +203,19 @@ autoscaling:
 # -- Persistent volume claim for data storage.
 # Automatically enabled when using filesystem storage or sqlite database driver.
 # Can be manually overridden with persistentVolumeClaim.enabled = true/false.
+#
+# NOTE: When using autoscaling (or replicaCount > 1) with the filesystem storage
+# driver, accessModes is automatically switched to ReadWriteMany so that multiple
+# pods can attach to the same volume. If you need a different access mode, set it
+# explicitly below.
+#
+# SQLite cannot be used with multiple replicas and will produce an install error.
 persistentVolumeClaim:
   # -- Set to true/false to explicitly enable/disable. If not set, automatically
   # enabled when storage.driver is "filesystem" or db.driver is "sqlite".
   enabled: null
+  # -- Access modes for the PVC. Automatically changed to ReadWriteMany when
+  # the filesystem storage driver is used with multiple replicas.
   accessModes:
     - ReadWriteOnce
   storage: 20Gi