kubernetes/common/mariadb-galera/values.yaml

# Copyright © 2018 Amdocs
# Copyright © 2018,2021 Bell Canada
# Copyright © 2019 Samsung Electronics
# Copyright © 2020 Bitnami, Orange
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

#################################################################
# Global configuration defaults.
#################################################################
global:
  nodePortPrefix: 302
  persistence:
    mountPath: /dockerdata-nfs
    backup:
      mountPath: /dockerdata-nfs/backup
  clusterDomain: cluster.local
  metrics: {}
  mariadbGalera:
    # flag to enable the DB creation via mariadb-operator
    useOperator: true
    # if useOperator set to "true", set "enableServiceAccount to "false"
    # as the SA is created by the Operator
    enableServiceAccount: false
    nameOverride: mariadb-galera
    service: mariadb-galera

#################################################################
# Secrets metaconfig
#################################################################
secrets:
  - uid: '{{ include "common.mariadb.secret.rootPassUID" . }}'
    type: password
    externalSecret: '{{ tpl (default "" .Values.rootUser.externalSecret) . }}'
    password: '{{ .Values.rootUser.password }}'
  - uid: '{{ include "common.mariadb.secret.userCredentialsUID" . }}'
    type: basicAuth
    externalSecret: '{{ tpl (default "" .Values.db.externalSecret) . }}'
    login: '{{ .Values.db.user }}'
    password: '{{ .Values.db.password }}'
  - uid: '{{ include "common.mariadb.secret.backupCredentialsUID" . }}'
    type: basicAuth
    externalSecret: '{{ tpl (default "" .Values.galera.mariabackup.externalSecret) . }}'
    login: '{{ .Values.galera.mariabackup.user }}'
    password: '{{ .Values.galera.mariabackup.password }}'

mariadbOperator:
  image: mariadb
  appVersion: 11.2.2
  persistence:
    #storageClassName: default
    size: 3Gi
  galera:
    enabled: true
    agentImage: mariadb-operator/mariadb-operator
    agentVersion: v0.0.28
    initImage: mariadb-operator/mariadb-operator
    initVersion: v0.0.28

## String to partially override common.names.fullname template (will maintain the release name)
##
nameOverride: mariadb-galera

## Custom db configuration
##
db:
  ## MariaDB username and password
  ## Password is ignored if externalSecret is specified.
  ## If not set, password will be "randomly" generated
  ## ref: https://github.com/bitnami/bitnami-docker-mariadb-galera#creating-a-database-user-on-first-run
  ##
  user: my-user
  # password:
  # externalSecret:
  ## Database to create
  ## ref: https://github.com/bitnami/bitnami-docker-mariadb-galera#creating-a-database-on-first-run
  ##
  # name: my_database

## Desired number of cluster nodes
##
replicaCount: 3

## Additional pod annotations for MariaDB Galera pods
## ref: https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/
## -> here required to enable mariadb-galera in istio
##
podAnnotations:
  #  sidecar.istio.io/inject: "false"
  traffic.sidecar.istio.io/excludeInboundPorts: "4444,4567,4568"
  traffic.sidecar.istio.io/includeInboundPorts: '*'
  traffic.sidecar.istio.io/excludeOutboundPorts: "4444,4567,4568,443"

mariadbOpConfiguration: |-
  [mysqld]
  max_allowed_packet=256M
  lower_case_table_names = 1

  ## Character set
  collation_server=utf8_unicode_ci
  init_connect='SET NAMES utf8'
  character_set_server=utf8

  ## MyISAM
  key_buffer_size=32M
  myisam_recover_options=FORCE,BACKUP

  ## Safety
  skip_host_cache
  skip_name_resolve
  max_allowed_packet=16M
  max_connect_errors=1000000
  sql_mode=STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_AUTO_VALUE_ON_ZERO,NO_ENGINE_SUBSTITUTION,NO_ZERO_DATE,NO_ZERO_IN_DATE,ONLY_FULL_GROUP_BY
  sysdate_is_now=1

  ## Caches and Limits
  tmp_table_size=32M
  max_heap_table_size=32M
  # Re-enabling as now works with Maria 10.1.2
  query_cache_type=1
  query_cache_limit=4M
  query_cache_size=256M
  max_connections=500
  thread_cache_size=50
  open_files_limit=65535
  table_definition_cache=4096
  table_open_cache=4096

  ## InnoDB
  innodb=FORCE
  innodb_strict_mode=1
  # Mandatory per https://github.com/codership/documentation/issues/25
  innodb_autoinc_lock_mode=2
  # Per https://www.percona.com/blog/2006/08/04/innodb-double-write/
  innodb_doublewrite=1
  innodb_flush_method=O_DIRECT
  innodb_log_files_in_group=2
  innodb_log_file_size=128M
  innodb_flush_log_at_trx_commit=1
  innodb_file_per_table=1
  # 80% Memory is default reco.
  # Need to re-evaluate when DB size grows
  innodb_buffer_pool_size=2G
  innodb_file_format=Barracuda

##########################################################################################
# !!! the following configuration entries are ignored, when mariadbOperator is enabled !!!
##########################################################################################
# bitnami image doesn't support well single quote in password
passwordStrengthOverride: basic

image: bitnami/mariadb-galera:10.5.8
## Specify a imagePullPolicy
## Defaults to 'Always' if image tag is 'latest', else set to 'IfNotPresent'
## ref: http://kubernetes.io/docs/user-guide/images/#pre-pulling-images
##
pullPolicy: Always

## Set to true if you would like to see extra information on logs
## It turns BASH debugging in minideb-extras-base
##
debug: true

## Sometimes, especially when a lot of pods are created at the same time,
## actions performed on the databases are tried to be done before actual start.
init_sleep_time: 5

## Use an alternate scheduler, e.g. "stork".
## ref: https://kubernetes.io/docs/tasks/administer-cluster/configure-multiple-schedulers/
##
# schedulerName:

## StatefulSet controller supports relax its ordering guarantees while preserving its uniqueness and identity guarantees. There are two valid pod management policies: OrderedReady and Parallel
## ref: https://kubernetes.io/docs/tutorials/stateful-application/basic-stateful-set/#pod-management-policy
##
podManagementPolicy: OrderedReady

## MariaDB Gallera K8s svc properties
##
service:
  ## Kubernetes service type and port number
  ##
  type: ClusterIP
  headless: {}
  internalPort: &dbPort 3306
  ports:
    - name: tcp-mysql
      port: *dbPort
  headlessPorts:
    - name: tcp-galera
      port: 4567
    - name: tcp-ist
      port: 4568
    - name: tcp-sst
      port: 4444


## Pods Service Account
## ref: https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/
##
serviceAccount:
  nameOverride: mariadb-galera
  roles:
    - read

## Pod Security Context
## ref: https://kubernetes.io/docs/tasks/configure-pod-container/security-context/
##
securityContext:
  enabled: true
  user_id: 10001
  group_id: 10001

## Database credentials for root (admin) user
##
rootUser:
  ## MariaDB admin user
  user: root
  ## MariaDB admin password
  ## Password is ignored if externalSecret is specified.
  ## If not set, password will be "randomly" generated
  ## ref: https://github.com/bitnami/bitnami-docker-mariadb-galera#setting-the-root-password-on-first-run
  ##
  # password:
  # externalSecret:

## Galera configuration
##
galera:
  ## Galera cluster name
  ##
  name: galera

  ## Bootstraping options
  ## ref: https://github.com/bitnami/bitnami-docker-mariadb-galera#bootstraping
  bootstrap:
    ## Node to bootstrap from, you will need to change this parameter incase you want to bootstrap from other node
    ##
    bootstrapFromNode:
    ## Force safe_to_bootstrap in grastate.date file.
    ## This will set safe_to_bootstrap=1 in the node indicated by bootstrapFromNode.
    forceSafeToBootstrap: false

  ## Credentials to perform backups
  ##
  mariabackup:
    ## MariaBackup username and password
    ## Password is ignored if externalSecret is specified.
    ## If not set, password will be "randomly" generated
    ## ref: https://github.com/bitnami/bitnami-docker-mariadb-galera#setting-up-a-multi-master-cluster
    ##
    user: mariabackup
    # password:
    # externalSecret:

## The backup job will mount the mariadb data pvc in order to run mariabackup.
## For this reason the db data pvc needs to have accessMode: ReadWriteMany.
backup:
  enabled: false
  # used in the mariadb-operator to override the backup name (default is DBName)
  # nameOverride:
  # defines the backup job execution period
  cron: "00 00 * * *"
  # used by mariadb-operator to set the max retention time
  maxRetention: 720h
  retentionPeriod: 3
  # used by mariadb-operator to set the backup storage type (PVC, S3, volume)
  storageType: PVC
  # configuration used for PVC backup storage
  persistence:
    ## If true, use a Persistent Volume Claim, If false, use emptyDir
    ##
    enabled: true
    # Enable persistence using an existing PVC
    # existingClaim:
    ## selector can be used to match an existing PersistentVolume
    ## selector:
    ##   matchLabels:
    ##     app: my-app
    selector: {}
    ## Persistent Volume Storage Class
    ## If defined, storageClassName: <storageClass>
    ## If set to "-", storageClassName: "", which disables dynamic provisioning
    ## If undefined (the default) or set to null, no storageClassName spec is
    ##   set, choosing the default provisioner.  (gp2 on AWS, standard on
    ##   GKE, AWS & OpenStack)
    ##
    # storageClass: "-"
    ## Persistent Volume Claim annotations
    ##
    annotations:
    ## Persistent Volume Access Mode
    ##
    accessMode: ReadWriteOnce
    ## Persistent Volume size
    ##
    size: 2Gi
  # requires mariadb-operator v0.24.0
  # configuration used for S3 backup storage
  # see: https://github.com/mariadb-operator/mariadb-operator/blob/main/docs/BACKUP.md
  s3:
    bucket: backups
    endpoint: minio.minio.svc.cluster.local:9000
    #region:  us-east-1
    accessKeyIdSecretKeyRef:
      name: minio
      key: access-key-id
    secretAccessKeySecretKeyRef:
      name: minio
      key: secret-access-key
    tls:
      enabled: false
      caSecretKeyRef:
        name: minio-ca
        key: ca.crt
  # configuration used for kubernetes volumes as backup storage
  # see: https://github.com/mariadb-operator/mariadb-operator/blob/main/docs/BACKUP.md
  volume: {}

readinessCheck:
  wait_for:
    services:
      - '{{ include "common.servicename" . }}'

## TLS configuration
##
tls:
  ## Enable TLS
  ##
  enabled: false
  ## Name of the secret that contains the certificates
  ##
  # certificatesSecret:
  ## Certificate filename
  ##
  # certFilename:
  ## Certificate Key filename
  ##
  # certKeyFilename:
  ## CA Certificate filename
  ##
  # certCAFilename:

## Configure MariaDB with a custom my.cnf file
## ref: https://mysql.com/kb/en/mysql/configuring-mysql-with-mycnf/#example-of-configuration-file
## Alternatively, you can put your my.cnf under the files/ directory
##
mariadbConfiguration: |-
  [client]
  port=3306
  socket=/opt/bitnami/mariadb/tmp/mysql.sock
  plugin_dir=/opt/bitnami/mariadb/plugin

  [mysqld]
  lower_case_table_names = 1
  default_storage_engine=InnoDB
  basedir=/opt/bitnami/mariadb
  datadir=/bitnami/mariadb/data
  plugin_dir=/opt/bitnami/mariadb/plugin
  tmpdir=/opt/bitnami/mariadb/tmp
  socket=/opt/bitnami/mariadb/tmp/mysql.sock
  pid_file=/opt/bitnami/mariadb/tmp/mysqld.pid
  bind_address=0.0.0.0

  ## Character set
  collation_server=utf8_unicode_ci
  init_connect='SET NAMES utf8'
  character_set_server=utf8

  ## MyISAM
  key_buffer_size=32M
  myisam_recover_options=FORCE,BACKUP

  ## Safety
  skip_host_cache
  skip_name_resolve
  max_allowed_packet=16M
  max_connect_errors=1000000
  sql_mode=STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_AUTO_VALUE_ON_ZERO,NO_ENGINE_SUBSTITUTION,NO_ZERO_DATE,NO_ZERO_IN_DATE,ONLY_FULL_GROUP_BY
  sysdate_is_now=1

  ## Binary Logging
  log_bin=mysql-bin
  expire_logs_days=14
  # Disabling for performance per http://severalnines.com/blog/9-tips-going-production-galera-cluster-mysql
  sync_binlog=0
  # Required for Galera
  binlog_format=row

  ## Caches and Limits
  tmp_table_size=32M
  max_heap_table_size=32M
  # Re-enabling as now works with Maria 10.1.2
  query_cache_type=1
  query_cache_limit=4M
  query_cache_size=256M
  max_connections=500
  thread_cache_size=50
  open_files_limit=65535
  table_definition_cache=4096
  table_open_cache=4096

  ## InnoDB
  innodb=FORCE
  innodb_strict_mode=1
  # Mandatory per https://github.com/codership/documentation/issues/25
  innodb_autoinc_lock_mode=2
  # Per https://www.percona.com/blog/2006/08/04/innodb-double-write/
  innodb_doublewrite=1
  innodb_flush_method=O_DIRECT
  innodb_log_files_in_group=2
  innodb_log_file_size=128M
  innodb_flush_log_at_trx_commit=1
  innodb_file_per_table=1
  # 80% Memory is default reco.
  # Need to re-evaluate when DB size grows
  innodb_buffer_pool_size=2G
  innodb_file_format=Barracuda

  ## Logging
  log_error=/opt/bitnami/mariadb/logs/mysqld.log
  slow_query_log_file=/opt/bitnami/mariadb/logs/mysqld.log
  log_queries_not_using_indexes=1
  slow_query_log=1

  ## SSL
  ## Use extraVolumes and extraVolumeMounts to mount /certs filesystem
  # ssl_ca=/certs/ca.pem
  # ssl_cert=/certs/server-cert.pem
  # ssl_key=/certs/server-key.pem

  [galera]
  wsrep_on=ON
  wsrep_provider=/opt/bitnami/mariadb/lib/libgalera_smm.so
  wsrep_sst_method=mariabackup
  wsrep_slave_threads=4
  wsrep_cluster_address=gcomm://
  wsrep_cluster_name=galera
  wsrep_sst_auth="root:"
  # Enabled for performance per https://mariadb.com/kb/en/innodb-system-variables/#innodb_flush_log_at_trx_commit
  innodb_flush_log_at_trx_commit=2
  # MYISAM REPLICATION SUPPORT #
  wsrep_replicate_myisam=ON
  binlog_format=row
  default_storage_engine=InnoDB
  innodb_autoinc_lock_mode=2
  transaction-isolation=READ-COMMITTED
  wsrep_causal_reads=1
  wsrep_sync_wait=7

  [mariadb]
  plugin_load_add=auth_pam

  ## Data-at-Rest Encryption
  ## Use extraVolumes and extraVolumeMounts to mount /encryption filesystem
  # plugin_load_add=file_key_management
  # file_key_management_filename=/encryption/keyfile.enc
  # file_key_management_filekey=FILE:/encryption/keyfile.key
  # file_key_management_encryption_algorithm=AES_CTR
  # encrypt_binlog=ON
  # encrypt_tmp_files=ON

  ## InnoDB/XtraDB Encryption
  # innodb_encrypt_tables=ON
  # innodb_encrypt_temporary_tables=ON
  # innodb_encrypt_log=ON
  # innodb_encryption_threads=4
  # innodb_encryption_rotate_key_age=1

  ## Aria Encryption
  # aria_encrypt_tables=ON
  # encrypt_tmp_disk_tables=ON

## MariaDB additional command line flags
## Can be used to specify command line flags, for example:
##
## extraFlags: "--max-connect-errors=1000 --max_connections=155"

## updateStrategy for MariaDB Master StatefulSet
## ref: https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/#update-strategies
##
updateStrategy:
  type: RollingUpdate

## Pod affinity preset
## ref: https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#inter-pod-affinity-and-anti-affinity
## Allowed values: soft, hard
##
podAffinityPreset: ""

## Pod anti-affinity preset
## Ref: https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#inter-pod-affinity-and-anti-affinity
## Allowed values: soft, hard
##
podAntiAffinityPreset: soft

## Node affinity preset
## Ref: https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/#node-affinity
## Allowed values: soft, hard
##
nodeAffinityPreset:
  ## Node affinity type
  ## Allowed values: soft, hard
  type: ""
  ## Node label key to match
  ## E.g.
  ## key: "kubernetes.io/e2e-az-name"
  ##
  key: ""
  ## Node label values to match
  ## E.g.
  ## values:
  ##   - e2e-az1
  ##   - e2e-az2
  ##
  values: []

## Affinity for pod assignment. Evaluated as a template.
## Ref: https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity
## Note: podAffinityPreset, podAntiAffinityPreset, and nodeAffinityPreset will be ignored when it's set
##
affinity: {}

## Node labels for pod assignment. Evaluated as a template.
## ref: https://kubernetes.io/docs/user-guide/node-selection/
##
nodeSelector: {}

## Tolerations for pod assignment. Evaluated as a template.
## ref: https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/
##
tolerations: []

## Enable persistence using Persistent Volume Claims
## ref: http://kubernetes.io/docs/user-guide/persistent-volumes/
##
persistence:
  ## If true, use a Persistent Volume Claim, If false, use emptyDir
  ##
  enabled: true
  # Enable persistence using an existing PVC
  # existingClaim:
  mountPath: /dockerdata-nfs
  mountSubPath: "mariadb-galera/data"
  ## selector can be used to match an existing PersistentVolume
  ## selector:
  ##   matchLabels:
  ##     app: my-app
  selector: {}
  ## Persistent Volume Storage Class
  ## If defined, storageClassName: <storageClass>
  ## If set to "-", storageClassName: "", which disables dynamic provisioning
  ## If undefined (the default) or set to null, no storageClassName spec is
  ##   set, choosing the default provisioner.  (gp2 on AWS, standard on
  ##   GKE, AWS & OpenStack)
  ##
  # storageClass: "-"
  ## Persistent Volume Claim annotations
  ##
  annotations:
  ## Persistent Volume Access Mode
  ## Use ReadWriteMany if backup is enabled, see backup section.
  ##
  accessMode: ReadWriteOnce
  ## Persistent Volume size
  ##
  size: 3Gi

## Additional pod labels
##
# podLabels:
#   extraLabel: extraValue

## Priority Class Name
#
# priorityClassName: 'priorityClass'

## MariaDB Galera containers' resource requests and limits
## ref: http://kubernetes.io/docs/user-guide/compute-resources/
##
flavor: small
resources:
  small:
    limits:
      cpu: "1"
      memory: "4Gi"
    requests:
      cpu: "500m"
      memory: "2Gi"
  large:
    limits:
      cpu: "2"
      memory: "6Gi"
    requests:
      cpu: "1"
      memory: "3Gi"
  unlimited: {}

## MariaDB Galera containers' liveness and readiness probes
## ref: https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle/#container-probes
##
livenessProbe:
  enabled: true
  initialDelaySeconds: 1
  periodSeconds: 10
  timeoutSeconds: 180
  successThreshold: 1
  failureThreshold: 3
readinessProbe:
  enabled: true
  initialDelaySeconds: 1
  periodSeconds: 10
  timeoutSeconds: 180
  successThreshold: 1
  failureThreshold: 3
startupProbe:
  ## Initializing the database could take some time
  ##
  enabled: true
  initialDelaySeconds: 10
  periodSeconds: 10
  timeoutSeconds: 180
  successThreshold: 1
  # will wait up for initialDelaySeconds + failureThreshold*periodSeconds before
  # stating startup wasn't good (910s per default)
  failureThreshold: 90

## Pod disruption budget configuration
##
podDisruptionBudget:
  ## Specifies whether a Pod disruption budget should be created
  ##
  create: true
  minAvailable: 1
  # maxUnavailable: 1

## Prometheus exporter configuration
##
metrics:
  ## Bitnami MySQL Prometheus exporter image
  ## ref: https://hub.docker.com/r/bitnami/mysqld-exporter/tags/
  ##
  image: bitnami/mysqld-exporter:0.12.1-debian-10-r264
  pullPolicy: Always
  ## MySQL exporter additional command line flags
  ## Can be used to specify command line flags
  ## E.g.:
  ## extraFlags:
  ##   - --collect.binlog_size
  ##
  extraFlags: []
  securityContext:
    readOnlyRootFilesystem: true
    privileged: false
    allowPrivilegeEscalation: false
    capabilities:
      drop:
        - ALL
        - CAP_NET_RAW
    runAsGroup: 10001
    runAsNonRoot: true
    runAsUser: 10001
    seccompProfile:
      type: RuntimeDefault
  ## MySQL Prometheus exporter containers' resource requests and limits
  ## ref: http://kubernetes.io/docs/user-guide/compute-resources/
  ##
  resources:
    # We usually recommend not to specify default resources and to leave this as a conscious
    # choice for the user. This also increases chances charts run on environments with little
    # resources, such as Minikube. If you do want to specify resources, uncomment the following
    # lines, adjust them as necessary, and remove the curly braces after 'resources:'.
    limits:
      cpu: "0.5"
      memory: "200Mi"
    requests:
      cpu: "0.5"
      memory: "200Mi"
  ## MariaDB Galera metrics container's liveness and readiness probes
  ## ref: https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle/#container-probes
  ##
  livenessProbe:
    enabled: true
    initialDelaySeconds: 30
    periodSeconds: 10
    timeoutSeconds: 5
    successThreshold: 1
    failureThreshold: 3
  readinessProbe:
    enabled: true
    initialDelaySeconds: 5
    periodSeconds: 10
    timeoutSeconds: 5
    successThreshold: 1
    failureThreshold: 3
  ## MySQL Prometheus exporter service parameters
  ##
  service:
    type: ClusterIP
    port: 9104
    annotations:
      prometheus.io/scrape: "true"
      prometheus.io/port: "9104"

  ## Prometheus Operator ServiceMonitor configuration
  ##
  serviceMonitor:
    enabled: false
    ## Namespace in which Prometheus is running
    ##
    # namespace: monitoring

    ## Interval at which metrics should be scraped.
    ## ref: https://github.com/coreos/prometheus-operator/blob/master/Documentation/api.md#endpoint
    ##
    # interval: 10s

    ## Timeout after which the scrape is ended
    ## ref: https://github.com/coreos/prometheus-operator/blob/master/Documentation/api.md#endpoint
    ##
    # scrapeTimeout: 10s

    ## ServiceMonitor selector labels
    ## ref: https://github.com/bitnami/charts/tree/master/bitnami/prometheus-operator#prometheus-configuration
    ##
    # selector:
    #   prometheus: kube-prometheus

    ## RelabelConfigs to apply to samples before scraping
    ## ref: https://github.com/coreos/prometheus-operator/blob/master/Documentation/api.md#relabelconfig
    ## Value is evalued as a template
    ##
    relabelings: []

    ## MetricRelabelConfigs to apply to samples before ingestion
    ## ref: https://github.com/coreos/prometheus-operator/blob/master/Documentation/api.md#relabelconfig
    ## Value is evalued as a template
    ##
    metricRelabelings: []
    #  - sourceLabels:
    #      - "__name__"
    #    targetLabel: "__name__"
    #    action: replace
    #    regex: '(.*)'
    #    replacement: 'example_prefix_$1'

  ## Prometheus Operator PrometheusRule configuration
  ##
  prometheusRules:
    enabled: false

    ## Additional labels to add to the PrometheusRule so it is picked up by the operator.
    ## If using the [Helm Chart](https://github.com/helm/charts/tree/master/stable/prometheus-operator) this is the name of the Helm release and 'app: prometheus-operator'
    selector:
      app: prometheus-operator
      release: prometheus

    ## Rules as a map.
    rules: []
    #  - alert: MariaDB-Down
    #    annotations:
    #      message: 'MariaDB instance {{ $labels.instance }} is down'
    #      summary: MariaDB instance is down
    #    expr: absent(up{job="mariadb-galera"} == 1)
    #    labels:
    #      severity: warning
    #      service: mariadb-galera
    #    for: 5m