# ConfigMap holding information about configuration files for primary/secondary and dockerinit
apiVersion: v1
kind: ConfigMap
metadata:
  name: mariadb-configmap
data:

  primary.cnf: |
    [mariadb]
    log-bin                         # enable binary logging
    log-basename=my-mariadb         # used to be independent of hostname changes (otherwise is in datadir/mysql)

  replica.cnf: |
    [mariadb]
    log-basename=my-mariadb         # used to be independent of hostname changes (otherwise is in datadir/mysql)

  primary.sql: |
    CREATE USER 'repluser'@'%' IDENTIFIED BY 'replsecret';
    GRANT REPLICATION REPLICA ON *.* TO 'repluser'@'%';
    CREATE DATABASE primary_db;

  secondary.sql: |
    # We have to know name of sts (`mariadb-sts`) and 
    # service `mariadb-service` in advance as an FQDN.
    # No need to use master_port
    CHANGE MASTER TO 
    MASTER_HOST='mariadb-sts-0.mariadb-service.default.svc.cluster.local',
    MASTER_USER='repluser',
    MASTER_PASSWORD='replsecret',
    MASTER_CONNECT_RETRY=10;

# Secret holds information about root password
---
apiVersion: v1
kind: Secret
metadata:
    name: mariadb-secret
type: Opaque
data:
  mariadb-root-password: c2VjcmV0 # echo -n 'secret'|base64

# Headless service
---
apiVersion: v1
kind: Service
metadata:
  name: mariadb-service
  labels:
    app: mariadb
spec:
  ports:
  - port: 3306
    name: mariadb-port
  clusterIP: None
  selector:
    app: mariadb

# Statefulset
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mariadb-sts
spec:
  serviceName: "mariadb-service"
  replicas: 3
  selector:
    matchLabels:
      app: mariadb
  template:
    metadata:
      labels:
        app: mariadb
    spec:
      initContainers:
      - name: init-mariadb
        image: mariadb
        imagePullPolicy: Always
        command:
        - bash
        - "-c"
        - |
          set -ex
          echo 'Starting init-mariadb';
          # Check config map to directory that already exists 
          # (but must be used as a volume for main container)
          ls /mnt/config-map
          # Statefulset has sticky identity, number should be last
          [[ `hostname` =~ -([0-9]+)$ ]] || exit 1
          ordinal=${BASH_REMATCH[1]}
          # Copy appropriate conf.d files from config-map to 
          # mariadb-config volume (emptyDir) depending on pod number
          if [[ $ordinal -eq 0 ]]; then
            # This file holds SQL for connecting to primary
            cp /mnt/config-map/primary.cnf /etc/mysql/conf.d/server-id.cnf
            # Create the users needed for replication on primary on a volume
            # initdb (emptyDir)
            cp /mnt/config-map/primary.sql /docker-entrypoint-initdb.d
          else
            # This file holds SQL for connecting to secondary
            cp /mnt/config-map/replica.cnf /etc/mysql/conf.d/server-id.cnf
            # On replicas use secondary configuration on initdb volume
            cp /mnt/config-map/secondary.sql /docker-entrypoint-initdb.d
          fi
          # Add an offset to avoid reserved server-id=0 value.
          echo server-id=$((3000 + $ordinal)) >> etc/mysql/conf.d/server-id.cnf
          ls /etc/mysql/conf.d/
          cat /etc/mysql/conf.d/server-id.cnf
        volumeMounts:
          - name: mariadb-config-map
            mountPath: /mnt/config-map
          - name: mariadb-config
            mountPath: /etc/mysql/conf.d/
          - name: initdb
            mountPath: /docker-entrypoint-initdb.d
      restartPolicy: Always
      containers:
      - name: mariadb
        image: mariadb
        ports:
        - containerPort: 3306
          name: mariadb-port
        env:
        # Using Secrets
        - name: MARIADB_ROOT_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mariadb-secret
              key: mariadb-root-password
        - name: MYSQL_INITDB_SKIP_TZINFO
          value: "1"
        # Mount volume from persistent volume claim
        volumeMounts:
        - name: datadir
          mountPath: /var/lib/mysql/
        - name: mariadb-config
          mountPath: /etc/mysql/conf.d/
        - name: initdb
          mountPath: /docker-entrypoint-initdb.d
      volumes:
      - name: mariadb-config-map
        configMap:
          name: mariadb-configmap
          #defaultMode: 0544
      - name: mariadb-config
        emptyDir: {}
      - name: initdb
        emptyDir: {}

  volumeClaimTemplates:
  - metadata:
      name: datadir
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 300M