feat(helm): Add persistence option to memcached on Helm chart (#13619)

Add an option to configure persistence on memcached, very useful with extstore option. More info on Grafana Blog post (https://grafana.com/blog/2023/08/23/how-we-scaled-grafana-cloud-logs-memcached-cluster-to-50tb-and-improved-reliability/), based mostly on `loki-distributed` Helm chart.
grafana · Sep 2, 2024 · ef1df0e · ef1df0e
1 parent 281407f
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diff --git a/docs/sources/setup/install/helm/reference.md b/docs/sources/setup/install/helm/reference.md
@@ -1623,6 +1623,56 @@ true
 			<td><pre lang="json">
 5
 </pre>
+</td>
+		</tr>
+		<tr>
+			<td>chunksCache.persistence</td>
+			<td>object</td>
+			<td>Persistence settings for the chunks-cache</td>
+			<td><pre lang="json">
+{
+  "enabled": false,
+  "mountPath": "/data",
+  "storageClass": null,
+  "storageSize": "10G"
+}
+</pre>
+</td>
+		</tr>
+		<tr>
+			<td>chunksCache.persistence.enabled</td>
+			<td>bool</td>
+			<td>Enable creating PVCs for the chunks-cache</td>
+			<td><pre lang="json">
+false
+</pre>
+</td>
+		</tr>
+		<tr>
+			<td>chunksCache.persistence.mountPath</td>
+			<td>string</td>
+			<td>Volume mount path</td>
+			<td><pre lang="json">
+"/data"
+</pre>
+</td>
+		</tr>
+		<tr>
+			<td>chunksCache.persistence.storageClass</td>
+			<td>string</td>
+			<td>Storage class to be used. If defined, storageClassName: <storageClass>. If set to "-", storageClassName: "", which disables dynamic provisioning. If empty or set to null, no storageClassName spec is set, choosing the default provisioner (gp2 on AWS, standard on GKE, AWS, and OpenStack).</td>
+			<td><pre lang="json">
+null
+</pre>
+</td>
+		</tr>
+		<tr>
+			<td>chunksCache.persistence.storageSize</td>
+			<td>string</td>
+			<td>Size of persistent disk</td>
+			<td><pre lang="json">
+"10G"
+</pre>
 </td>
 		</tr>
 		<tr>
@@ -9035,6 +9085,56 @@ true
 			<td><pre lang="json">
 {}
 </pre>
+</td>
+		</tr>
+		<tr>
+			<td>resultsCache.persistence</td>
+			<td>object</td>
+			<td>Persistence settings for the results-cache</td>
+			<td><pre lang="json">
+{
+  "enabled": false,
+  "mountPath": "/data",
+  "storageClass": null,
+  "storageSize": "10G"
+}
+</pre>
+</td>
+		</tr>
+		<tr>
+			<td>resultsCache.persistence.enabled</td>
+			<td>bool</td>
+			<td>Enable creating PVCs for the results-cache</td>
+			<td><pre lang="json">
+false
+</pre>
+</td>
+		</tr>
+		<tr>
+			<td>resultsCache.persistence.mountPath</td>
+			<td>string</td>
+			<td>Volume mount path</td>
+			<td><pre lang="json">
+"/data"
+</pre>
+</td>
+		</tr>
+		<tr>
+			<td>resultsCache.persistence.storageClass</td>
+			<td>string</td>
+			<td>Storage class to be used. If defined, storageClassName: <storageClass>. If set to "-", storageClassName: "", which disables dynamic provisioning. If empty or set to null, no storageClassName spec is set, choosing the default provisioner (gp2 on AWS, standard on GKE, AWS, and OpenStack).</td>
+			<td><pre lang="json">
+null
+</pre>
+</td>
+		</tr>
+		<tr>
+			<td>resultsCache.persistence.storageSize</td>
+			<td>string</td>
+			<td>Size of persistent disk</td>
+			<td><pre lang="json">
+"10G"
+</pre>
 </td>
 		</tr>
 		<tr>

diff --git a/production/helm/loki/CHANGELOG.md b/production/helm/loki/CHANGELOG.md
@@ -13,6 +13,10 @@ Entries should include a reference to the pull request that introduced the chang
 
 [//]: # (<AUTOMATED_UPDATES_LOCATOR> : do not remove this line. This locator is used by the CI pipeline to automatically create a changelog entry for each new Loki release. Add other chart versions and respective changelog entries bellow this line.)
 
+## 6.11.0
+
+- [FEATURE] Add support for configuring persistence for memcached.
+
 ## 6.10.2
 
 - [CHANGE] Bumped version of `nginxinc/nginx-unprivileged` to 1.27-alpine; this remediates several CVE
@@ -27,7 +31,6 @@ Entries should include a reference to the pull request that introduced the chang
 - [CHANGE] Changed version of Grafana Loki to 3.1.1
 - [ENHANCEMENT] Added ability to disable AWS S3 dualstack endpoint usage.
 
-
 ## 6.9.0
 
 - [BUGFIX] Fixed how we set imagePullSecrets for the memcached and provisioner.

diff --git a/production/helm/loki/Chart.yaml b/production/helm/loki/Chart.yaml
@@ -3,7 +3,7 @@ name: loki
 description: Helm chart for Grafana Loki and Grafana Enterprise Logs supporting both simple, scalable and distributed modes.
 type: application
 appVersion: 3.1.1
-version: 6.10.2
+version: 6.11.0
 home: https://grafana.github.io/helm-charts
 sources:
   - https://github.com/grafana/loki

diff --git a/production/helm/loki/README.md b/production/helm/loki/README.md
@@ -1,6 +1,6 @@
 # loki
 
-![Version: 6.10.2](https://img.shields.io/badge/Version-6.10.2-informational?style=flat-square) ![Type: application](https://img.shields.io/badge/Type-application-informational?style=flat-square) ![AppVersion: 3.1.1](https://img.shields.io/badge/AppVersion-3.1.1-informational?style=flat-square)
+![Version: 6.11.0](https://img.shields.io/badge/Version-6.11.0-informational?style=flat-square) ![Type: application](https://img.shields.io/badge/Type-application-informational?style=flat-square) ![AppVersion: 3.1.1](https://img.shields.io/badge/AppVersion-3.1.1-informational?style=flat-square)
 
 Helm chart for Grafana Loki and Grafana Enterprise Logs supporting both simple, scalable and distributed modes.
 

diff --git a/production/helm/loki/templates/memcached/_memcached-statefulset.tpl b/production/helm/loki/templates/memcached/_memcached-statefulset.tpl
@@ -104,7 +104,7 @@ spec:
               name: client
           args:
             - -m {{ .allocatedMemory }}
-            - --extended=modern,track_sizes{{ with .extraExtendedOptions }},{{ . }}{{ end }}
+            - --extended=modern,track_sizes{{ if .persistence.enabled }},ext_path={{ .persistence.mountPath }}/file:{{ .persistence.storageSize }}{{ end }}{{ with .extraExtendedOptions }},{{ . }}{{ end }}
             - -I {{ .maxItemMemory }}m
             - -c {{ .connectionLimit }}
             - -v
@@ -122,10 +122,16 @@ spec:
             {{- end }}
           securityContext:
             {{- toYaml $.ctx.Values.memcached.containerSecurityContext | nindent 12 }}
-          {{- if .extraVolumeMounts }}
+          {{- if or .persistence.enabled .extraVolumeMounts }}
           volumeMounts:
+          {{- if .persistence.enabled }}
+            - name: data
+              mountPath: {{ .persistence.mountPath }}
+          {{- end }}
+          {{- if .extraVolumeMounts }}
             {{- toYaml .extraVolumeMounts | nindent 12 }}
           {{- end }}
+          {{- end }}
 
       {{- if $.ctx.Values.memcachedExporter.enabled }}
         - name: exporter
@@ -151,6 +157,19 @@ spec:
             {{- toYaml .extraVolumeMounts | nindent 12 }}
           {{- end }}
       {{- end }}
+  {{- if .persistence.enabled }}
+  volumeClaimTemplates:
+    - metadata:
+        name: data
+      spec:
+        accessModes: [ "ReadWriteOnce" ]
+        {{- with .persistence.storageClass }}
+        storageClassName: {{ if (eq "-" .) }}""{{ else }}{{ . }}{{ end }}
+        {{- end }}
+        resources:
+          requests:
+            storage: {{ .persistence.storageSize | quote }}
+  {{- end }}
 {{- end -}}
 {{- end -}}
 {{- end -}}

diff --git a/production/helm/loki/values.yaml b/production/helm/loki/values.yaml
@@ -2967,6 +2967,20 @@ resultsCache:
   service:
     annotations: {}
     labels: {}
+  # -- Persistence settings for the results-cache
+  persistence:
+    # -- Enable creating PVCs for the results-cache
+    enabled: false
+    # -- Size of persistent disk
+    storageSize: 10G
+    # -- Storage class to be used.
+    # If defined, storageClassName: <storageClass>.
+    # If set to "-", storageClassName: "", which disables dynamic provisioning.
+    # If empty or set to null, no storageClassName spec is
+    # set, choosing the default provisioner (gp2 on AWS, standard on GKE, AWS, and OpenStack).
+    storageClass: null
+    # -- Volume mount path
+    mountPath: /data
 chunksCache:
   # -- Specifies whether memcached based chunks-cache should be enabled
   enabled: true
@@ -3055,6 +3069,20 @@ chunksCache:
   service:
     annotations: {}
     labels: {}
+  # -- Persistence settings for the chunks-cache
+  persistence:
+    # -- Enable creating PVCs for the chunks-cache
+    enabled: false
+    # -- Size of persistent disk
+    storageSize: 10G
+    # -- Storage class to be used.
+    # If defined, storageClassName: <storageClass>.
+    # If set to "-", storageClassName: "", which disables dynamic provisioning.
+    # If empty or set to null, no storageClassName spec is
+    # set, choosing the default provisioner (gp2 on AWS, standard on GKE, AWS, and OpenStack).
+    storageClass: null
+    # -- Volume mount path
+    mountPath: /data
 ######################################################################################################################
 #
 # Subchart configurations