[mariadb] slow-log housekeeping, dedicated slow-log volume, PVC-free alert

common/mariadb/CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## v0.43.0 - 2026/09/11
+* prune slow-query logs older than `slow_query_log.cleanup.max_age_days` (default 14) on pod init
+* optionally write the slow query log to a dedicated PVC (`slow_query_log.persistence`); it is written per-pod as `<dir>/<pod>-slow.log` so `cleanup` prunes it across restarts, and the PVC auto-provisions as `<release>-mariadb-logs` by default
+* opt-in data-PVC free-space alert at `alerts.pvc_free_enabled` (threshold `alerts.pvc_free_threshold`, default 0.20; severity `alerts.pvc_free_severity`, default warning)
+* fix `context` label typo (`datbase`) on the too-many-connections alert
+* chart version bumped
+
 ## v0.42.2 - 2026/08/25
 * MariaDB version updated to [10.11.19](https://mariadb.com/docs/release-notes/community-server/10.11/10.11.19)
 * `maria-back-me-up` updated to `10.11-20260825091346`

common/mariadb/Chart.yaml

@@ -2,7 +2,7 @@
 apiVersion: v2
 description: A Helm chart for Kubernetes
 name: mariadb
-version: 0.42.2
+version: 0.43.0
 # scripts/docker-entyrpoint.sh should be updated when appVersion is updated
 appVersion: 10.11.19
 dependencies:

common/mariadb/templates/_helpers.tpl

@@ -12,6 +12,35 @@
 {{- end -}}
 {{- end -}}
 
+{{/* MariaDB data directory (datadir mount point). */}}
+{{- define "mariadb.dataDir" -}}
+/var/lib/mysql
+{{- end -}}
+
+{{/* Name of the data PVC; keeps the deployment claimName and the volume alert in sync. */}}
+{{- define "mariadb.dataPvcName" -}}
+{{- .Values.persistence_claim.name | default (include "fullName" .) -}}
+{{- end -}}
+
+{{/* Name of the dedicated slow-log PVC referenced by the deployment. */}}
+{{- define "mariadb.slowLogPvcName" -}}
+{{- .Values.slow_query_log.persistence.name | default (printf "%s-logs" (include "fullName" .)) -}}
+{{- end -}}
+
+{{/* Directory the slow query log lives in (dedicated volume mount point). */}}
+{{- define "mariadb.slowLogDir" -}}
+{{- .Values.slow_query_log.dir -}}
+{{- end -}}
+
+{{/* Directory scanned by the slow-log cleanup: the dedicated volume when enabled, else the datadir. */}}
+{{- define "mariadb.slowLogCleanupDir" -}}
+{{- if .Values.slow_query_log.persistence.enabled -}}
+{{- include "mariadb.slowLogDir" . -}}
+{{- else -}}
+{{- include "mariadb.dataDir" . -}}
+{{- end -}}
+{{- end -}}
+
 {{- define "mariadb.resolve_secret_squote" -}}
     {{- $str := . -}}
     {{- if (hasPrefix "vault+kvv2" $str ) -}}

common/mariadb/templates/alerts.yaml

@@ -30,4 +30,7 @@ spec:
 {{- if .Values.alerts.alert_db_not_ready }}
 {{ include (print .Template.BasePath "/alerts/_health.alerts.tpl") . | indent 2 }}
 {{- end }}
+{{- if .Values.alerts.pvc_free_enabled }}
+{{ include (print .Template.BasePath "/alerts/_volume.alerts.tpl") . | indent 2 }}
+{{- end }}
 {{- end}}

common/mariadb/templates/alerts/_mysql.alerts.tpl

@@ -4,7 +4,7 @@
     expr: (mysql_global_variables_max_connections{app_kubernetes_io_instance=~"{{ include "fullName" . }}"} - mysql_global_status_threads_connected{app_kubernetes_io_instance=~"{{ include "fullName" . }}"} < 200)
     for: 10m
     labels:
-      context: datbase
+      context: database
       service: {{ include "alerts.service" . }}
       severity: info
       tier: {{ required ".Values.alerts.tier missing" .Values.alerts.tier }}

common/mariadb/templates/alerts/_volume.alerts.tpl

@@ -0,0 +1,15 @@
+- name: volume.alerts
+  rules:
+  - alert: {{ include "alerts.service" . | title }}MariaDBVolumeNearlyFull
+    {{- $pvc := include "mariadb.dataPvcName" . }}
+    expr: (kubelet_volume_stats_available_bytes{persistentvolumeclaim="{{ $pvc }}"} / kubelet_volume_stats_capacity_bytes{persistentvolumeclaim="{{ $pvc }}"}) < {{ .Values.alerts.pvc_free_threshold }}
+    for: 10m
+    labels:
+      context: database
+      service: {{ include "alerts.service" . }}
+      severity: {{ .Values.alerts.pvc_free_severity | default "warning" }}
+      tier: {{ required ".Values.alerts.tier missing" .Values.alerts.tier }}
+      support_group: {{ required ".Values.alerts.support_group missing" .Values.alerts.support_group }}
+    annotations:
+      description: The {{ include "fullName" . }} data volume has less than {{ mulf .Values.alerts.pvc_free_threshold 100 }}% free space left. If it fills up, MariaDB stops accepting writes.
+      summary: {{ include "fullName" . }} data volume is running low on free space.

common/mariadb/templates/deployment.yaml

@@ -81,6 +81,32 @@ spec:
             readOnly: true
           - name: init-file-root-sql
             mountPath: /etc/mysql/init-file
+{{- if or .Values.slow_query_log.persistence.enabled .Values.slow_query_log.cleanup.enabled }}
+      - name: slow-log-prepare
+        image: {{ required ".Values.global.dockerHubMirrorAlternateRegion is missing" .Values.global.dockerHubMirrorAlternateRegion }}/{{ .Values.image }}
+        imagePullPolicy: {{ default "IfNotPresent" .Values.imagePullPolicy | quote }}
+        securityContext:
+          runAsUser: 0
+        command:
+          - /bin/bash
+          - -c
+          - |
+{{- if .Values.slow_query_log.persistence.enabled }}
+            [ "$(stat -c %U {{ include "mariadb.slowLogDir" . }})" = mysql ] || chown -R mysql:mysql {{ include "mariadb.slowLogDir" . }}
+{{- end }}
+{{- if .Values.slow_query_log.cleanup.enabled }}
+            find {{ include "mariadb.slowLogCleanupDir" . }} -maxdepth 1 -type f -name '*slow*.log*' -mtime +{{ .Values.slow_query_log.cleanup.max_age_days }} -delete 2>/dev/null || true
+{{- end }}
+            exit 0
+        volumeMounts:
+{{- if .Values.slow_query_log.persistence.enabled }}
+          - name: mariadb-logs-storage
+            mountPath: {{ include "mariadb.slowLogDir" . }}
+{{- else if .Values.persistence_claim.enabled }}
+          - name: mariadb-persistent-storage
+            mountPath: {{ include "mariadb.dataDir" . }}
+{{- end }}
+{{- end }}
 {{- if .Values.global.mariadb.native_sidecar.enabled }}
 {{- else }}
       containers:
@@ -200,6 +226,14 @@ spec:
             secretKeyRef:
               name: mariadb-{{.Values.name}}
               key: root-password
+{{- if .Values.slow_query_log.persistence.enabled }}
+        - name: POD_NAME
+          valueFrom:
+            fieldRef:
+              fieldPath: metadata.name
+        args:
+          - --slow-query-log-file={{ required "slow_query_log.dir required when slow_query_log.persistence.enabled" .Values.slow_query_log.dir }}/$(POD_NAME)-slow.log
+{{- end }}
         ports:
           - name: mariadb
             containerPort: 3306
@@ -230,8 +264,12 @@ spec:
             mountPath: /run/mysqld
 {{- if .Values.persistence_claim.enabled }}
           - name: mariadb-persistent-storage
-            mountPath: /var/lib/mysql
+            mountPath: {{ include "mariadb.dataDir" . }}
             readOnly: false
+{{- end }}
+{{- if .Values.slow_query_log.persistence.enabled }}
+          - name: mariadb-logs-storage
+            mountPath: {{ include "mariadb.slowLogDir" . }}
 {{- end }}
           - mountPath: /usr/local/bin/docker-entrypoint.sh
             subPath: docker-entrypoint.sh
@@ -271,7 +309,12 @@ spec:
 {{- if .Values.persistence_claim.enabled }}
         - name: mariadb-persistent-storage
           persistentVolumeClaim:
-           claimName: {{ .Values.persistence_claim.name |  default (include "fullName" . ) }}
+           claimName: {{ include "mariadb.dataPvcName" . }}
+{{- end }}
+{{- if .Values.slow_query_log.persistence.enabled }}
+        - name: mariadb-logs-storage
+          persistentVolumeClaim:
+            claimName: {{ include "mariadb.slowLogPvcName" . }}
 {{- end }}
         - name: initdb
           secret:

common/mariadb/templates/pvc.yaml

@@ -19,3 +19,25 @@ spec:
   storageClassName: {{ .Values.persistence_claim.storage_class }}
   {{- end }}
 {{ end }}
+{{- if and .Values.slow_query_log.persistence.enabled .Values.slow_query_log.persistence.autoprovision }}
+---
+kind: PersistentVolumeClaim
+apiVersion: v1
+metadata:
+  name: {{ include "mariadb.slowLogPvcName" . }}
+  labels:
+    {{- include "mariadb.labels" (list $ "noversion" "mariadb" "persistentvolumeclaim" "database") | indent 4 }}
+spec:
+{{- if .Values.slow_query_log.persistence.access_modes }}
+  accessModes:
+  {{- range $accessMode := .Values.slow_query_log.persistence.access_modes }}
+  - {{ $accessMode }}
+  {{- end }}
+{{- end }}
+  resources:
+    requests:
+      storage: {{ .Values.slow_query_log.persistence.size }}
+  {{- if .Values.slow_query_log.persistence.storage_class }}
+  storageClassName: {{ .Values.slow_query_log.persistence.storage_class }}
+  {{- end }}
+{{ end }}

common/mariadb/values.yaml

@@ -19,12 +19,27 @@ log_warnings: "2"
 query_cache_size: "0"
 query_cache_type: "0"
 join_buffer_size: "4M"
-long_query_time: 5
 binlog_format: "MIXED"
 expire_logs_days: 10
 character_set_server: "utf8" # Should be utf8mb4, but we started with this
 collation_server: "utf8_general_ci"
 
+long_query_time: 5
+slow_query_log:
+  dir: /var/log/mysql-slow  # ignored when persistence.enabled=false
+  cleanup:
+    enabled: true  # removes old slowlogs on pod init
+    max_age_days: 14
+  persistence:
+    enabled: false
+    autoprovision: false
+    # name: defaults to <release>-mariadb-logs
+    size: "5Gi"
+    access_modes:
+      - ReadWriteOnce
+    # storage_class:
+
+
 db_performance_schema: # Enabling performance schema only (without enabling instruments for data collections).
   # Instrument can be enabled separately. Only Performance Schema Enablement does not cause any
   # overhead.
@@ -348,6 +363,11 @@ alerts:
   # Ratio of free pages below which MariaDBBufferPoolExhausted (critical) fires.
   buffer_pool_critical_threshold: 0.025
 
+  # Warn when the data PVC free ratio drops below pvc_free_threshold.
+  pvc_free_enabled: false
+  pvc_free_threshold: 0.20
+  pvc_free_severity: warning
+
 vpa:
   # https://github.com/sapcc/vpa_butler
   # The maximum available capacity is split evenly across containers specified in the Deployment, StatefulSet or DaemonSet to derive the upper recommendation bound. This does not work out for pods with a single resource-hungry container with several sidecar containers