useStatefulSet switch in revad for stateful workloads

This is specially useful when running into sharded scenarios as
e.g. different storage providers to map users with different
rules. Ref. cs3org/reva#1142

This commit contains a preliminary version, where the "real"
uniqueness of each replica in the set (in terms of config) is yet
to be implemented. First version will simply rely on the hostname
as selector inside the 'configFiles' value for a user-provided
toml file.

revad/Chart.yaml

@@ -3,8 +3,8 @@ apiVersion: v2
 name: revad
 description: The Reva daemon (revad) helm chart
 type: application
-version: 1.2.0
-appVersion: v1.2.0
+version: 1.2.1
+appVersion: v1.2.1
 icon: https://reva.link/logo.svg
 home: https://reva.link
 source: https://github.com/cs3org/reva

revad/README.md

@@ -41,6 +41,7 @@ The following configurations may be set. It is recommended to use `values.yaml`
 | `extraVolumeMounts`                               | Array of additional volume mounts.                                                                           | `[]`                                                                                                                    |
 | `extraVolumes`                                    | Array of additional volumes.                                                                                 | `[]`                                                                                                                    |
 | `emptyDir.sizeLimit`                              | `emptyDir` `sizeLimit` if a Persistent Volume is not used                                                    | `""`                                                                                                                    |
+| `useStatefulSet`                                  | If true, Revad will be deployed using a `StatefulSet` rather than the usual `Deployment`.                    | `false`                                                                                                                 |
 | `persistentVolume.enabled`                        | If true, Revad will create a Persistent Volume Claim.                                                        | `false`                                                                                                                 |
 | `persistentVolume.accessModes`                    | Revad data Persistent Volume access modes.                                                                   | `[ReadWriteOnce]`                                                                                                       |
 | `persistentVolume.annotations`                    | Revad data Persistent Volume annotations.                                                                    | `{}`                                                                                                                    |
@@ -62,3 +63,8 @@ The following configurations may be set. It is recommended to use `values.yaml`
 $ helm install custom-reva cs3org/revad \
   --set-file configFiles.revad\\.toml=custom-config.toml
 ```
+
+### Stateful deployment
+
+```console
+```

revad/templates/deployment.yaml

@@ -1,10 +1,13 @@
 apiVersion: apps/v1
-kind: Deployment
+kind: {{ if .Values.useStatefulSet }}{{ "StatefulSet" }}{{- else }}{{ "Deployment" }}{{- end }}
 metadata:
   name: {{ include "revad.fullname" . }}
   labels:
     {{- include "revad.labels" . | nindent 4 }}
 spec:
+  {{- if .Values.useStatefulSet }}
+  serviceName: {{ include "revad.fullname" . }}
+  {{- end }}
   replicas: {{ .Values.replicaCount }}
   selector:
     matchLabels:
@@ -51,18 +54,40 @@ spec:
         - name: {{ include "revad.fullname" . }}-configfiles
           configMap:
             name: {{ template "revad.fullname" . }}-config
+      {{- if .Values.extraVolumes }}
+        {{ toYaml .Values.extraVolumes | nindent 8 }}
+      {{- end }}
+    {{- if .Values.persistentVolume.enabled }}
+      {{- if .Values.useStatefulSet }}
+  volumeClaimTemplates:
+    - metadata:
+        name: {{ include "revad.fullname" . }}-datadir
+        {{- if .Values.persistentVolume.annotations }}
+        annotations:
+          {{- toYaml .Values.persistentVolume.annotations | indent 10 }}
+        {{- end }}
+      spec:
+        accessModes:
+          {{- toYaml .Values.persistentVolume.accessModes | indent 10 }}
+        resources:
+          requests: 
+            storage: "{{ .Values.persistentVolume.size }}"
+          {{- if (eq "-" .Values.persistentVolume.storageClass) }}
+            storageClassName: ""
+          {{- else }}
+            storageClassName: "{{ .Values.persistentVolume.storageClass }}"
+          {{- end }}
+      {{- else }}
         - name: {{ include "revad.fullname" . }}-datadir
-        {{- if .Values.persistentVolume.enabled }}
           persistentVolumeClaim:
             claimName: {{ if .Values.persistentVolume.existingClaim }}{{ .Values.persistentVolume.existingClaim }}{{- else }}{{ template "revad.fullname" . }}{{- end }}
-        {{- else }}
+      {{- end }}
+    {{- else }}
+        - name: {{ include "revad.fullname" . }}-datadir
           emptyDir:
           {{- if .Values.emptyDir.sizeLimit }}
             sizeLimit: {{ .Values.emptyDir.sizeLimit }}
           {{- else }}
             {}
           {{- end -}}
-        {{- end -}}
-        {{- if .Values.extraVolumes }}
-          {{ toYaml .Values.extraVolumes | nindent 8 }}
-        {{- end }}
+    {{- end }}

revad/templates/service.yaml

@@ -5,7 +5,11 @@ metadata:
   labels:
     {{- include "revad.labels" . | nindent 4 }}
 spec:
+  {{- if .Values.useStatefulSet }}
+  clusterIP: None
+  {{- else }}
   type: {{ .Values.service.type }}
+  {{- end }}
   ports:
     {{- if .Values.service.http }}
     - port: {{ .Values.service.http.port }}

revad/values.yaml

@@ -18,6 +18,8 @@ extraVolumes: []
 emptyDir:
   sizeLimit: ""
 
+useStatefulSet: false
+
 persistentVolume:
   ## If true, revad will create/use a Persistent Volume Claim
   ## If false, use emptyDir