pg-slave-statefulset.yaml

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: pg-slave
spec:
  serviceName: pg-slave
  replicas: 1  # Adjust replicas as needed
  selector:
    matchLabels:
      app: postgres
      role: slave
  template:
    metadata:
      labels:
        app: postgres
        role: slave
    spec:
      containers:
      - name: postgres
        image: postgres:15
        env:
        - name: POSTGRES_USER
          value: "postgres"
        - name: POSTGRES_PASSWORD
          value: "password"
        - name: PGDATA
          value: "/var/lib/postgresql/data"
        - name: PG_MASTER_HOST
          value: "pg-master"
        - name: PG_PORT
          value: "5432"
        volumeMounts:
        - name: pg-data
          mountPath: /var/lib/postgresql/data
        - name: pg-config-path
          mountPath: /etc/postgresql/custom
        - name: pg-scripts-config-path
          mountPath: /scripts/postgresql.sh
          subPath: postgresql.sh
        securityContext:
          runAsUser: 999  # PostgreSQL user UID
          runAsGroup: 999  # PostgreSQL group GID
        command:
        - "bash"
        - "-c"
        - |
          "/scripts/postgresql.sh"
          echo "include '/etc/postgresql/custom/postgresql.conf'" >> /var/lib/postgresql/data/postgresql.conf
          cat  /etc/postgresql/custom/pg_hba.conf >> /var/lib/postgresql/data/pg_hba.conf
          postgres

          # Extract replica name from the pod's hostname (e.g., pg-slave-0)
#          REPLICA_NAME=$(hostname | sed 's/-/_/g')
#
#          rm -rf /var/lib/postgresql/data/*  # Ensure the directory is empty
#          until pg_isready --host=$PG_MASTER_HOST --port=$PG_PORT; do
#            echo "Waiting for master to be ready..."
#            sleep 2
#          done
#          pg_basebackup -h $PG_MASTER_HOST -D /tmp/pgdata -U postgres -v -P --wal-method=stream
#          mv /tmp/pgdata/* /var/lib/postgresql/data/
#          chown -R postgres:postgres /var/lib/postgresql/data
#          psql -h $PG_MASTER_HOST -U postgres -c "SELECT pg_create_physical_replication_slot('${REPLICA_NAME}');"
#          echo "primary_slot_name = '${REPLICA_NAME}'" | tee -a /var/lib/postgresql/data/postgresql.conf
#          echo "primary_conninfo = 'host=$PG_MASTER_HOST port=$PG_PORT user=postgres password=password application_name=${REPLICA_NAME}'" | tee -a /var/lib/postgresql/data/postgresql.conf
#          touch /var/lib/postgresql/data/standby.signal
#          chmod 700 /var/lib/postgresql/data/
#          rm -rf /tmp/pgdata
#          echo "Starting PostgreSQL..."
#          exec postgres  # Use exec to replace the shell with the PostgreSQL process

        lifecycle:
          preStop:
            exec:
              command:
                - "bash"
                - "-c"
                - |
                  REPLICA_NAME=$(hostname | sed 's/-/_/g')
                  echo "Deleting replication slot ${REPLICA_NAME} from master..."
                  psql -h $PG_MASTER_HOST -U postgres -p $PG_PORT -c "SELECT pg_drop_replication_slot('${REPLICA_NAME}');"

      volumes:
      - name: pg-data
        persistentVolumeClaim:
          claimName: pg-slave-pvc
      - name: pg-config-path
        configMap:
          name: pg-config
          defaultMode: 0755
      - name: pg-scripts-config-path
        configMap:
          name: pg-script-config
          defaultMode: 0755