docker clustered master fail tolerance postgresql

```xml
version: '3'
# docker network create --driver overlay cluster

networks:
    cluster:
      external: true

services:
    pgmaster:
        image: paunin/postdock-pgsql
        environment:
            PARTNER_NODES: "pgmaster,pgslave1,pgslave3"
            NODE_ID: 1 # Integer number of node
            NODE_NAME: node1 # Node name
            CLUSTER_NODE_NETWORK_NAME: pgmaster # (default: hostname of the node)
            NODE_PRIORITY: 100  # (default: 100)
            SSH_ENABLE: 1
            #database we want to use for application
            POSTGRES_PASSWORD: monkey_pass
            POSTGRES_USER: monkey_user
            POSTGRES_DB: monkey_db
            CLEAN_OVER_REWIND: 0
            CONFIGS: "listen_addresses:'*',max_replication_slots:5"
                                  # in format variable1:value1[,variable2:value2[,...]]
                                  # used for pgpool.conf file
            #defaults:
            CLUSTER_NAME: pg_cluster # default is pg_cluster
            REPLICATION_DB: replication_db # default is replication_db
            REPLICATION_USER: replication_user # default is replication_user
            REPLICATION_PASSWORD: replication_pass # default is replication_pass

        volumes:
            - pgmaster:/var/lib/postgresql/data
        networks:
            cluster:
                aliases:
                    - pgmaster
    pgslave1:
        image: paunin/postdock-pgsql
        environment:
            PARTNER_NODES: "pgmaster,pgslave1,pgslave3"
            REPLICATION_PRIMARY_HOST: pgmaster
            NODE_ID: 2
            NODE_NAME: node2
            CLUSTER_NODE_NETWORK_NAME: pgslave1 # (default: hostname of the node)
            CLEAN_OVER_REWIND: 1
            CONFIGS: "max_replication_slots:10" #some overrides
        volumes:
            - pgslave1:/var/lib/postgresql/data
        networks:
            cluster:
                aliases:
                    - pgslave1

    backup:
        image: paunin/postdock-barman
        environment:
            REPLICATION_USER: replication_user # default is replication_user
            REPLICATION_PASSWORD: replication_pass # default is replication_pass
            REPLICATION_HOST: pgmaster
            POSTGRES_PASSWORD: monkey_pass
            POSTGRES_USER: monkey_user
            POSTGRES_DB: monkey_db
            SSH_ENABLE: 1
            BACKUP_SCHEDULE: "*/30 */5 * * *"
        volumes:
            - backup:/var/backups
        networks:
            cluster:
                aliases:
                    - backup
    pgpool:
        image: paunin/postdock-pgpool
        environment:
            PCP_USER: pcp_user
            PCP_PASSWORD: pcp_pass
            WAIT_BACKEND_TIMEOUT: 60

            CHECK_USER: monkey_user
            CHECK_PASSWORD: monkey_pass
            CHECK_PGCONNECT_TIMEOUT: 1 #timout for checking if primary node is healthy
            SSH_ENABLE: 1
            DB_USERS: monkey_user:monkey_pass # in format user:password[,user:password[...]]
            BACKENDS: "0:pgmaster:5432:1:/var/lib/postgresql/data:ALLOW_TO_FAILOVER,1:pgslave1::::" #,4:pgslaveDOES_NOT_EXIST::::
                      # in format num:host:port:weight:data_directory:flag[,...]
                      # defaults:
                      #   port: 5432
                      #   weight: 1
                      #   data_directory: /var/lib/postgresql/data
                      #   flag: ALLOW_TO_FAILOVER
            REQUIRE_MIN_BACKENDS: 1 # minimal number of backends to start pgpool (some might be unreachable)
            CONFIGS: "num_init_children:250,max_pool:4"
                      # in format variable1:value1[,variable2:value2[,...]]
                      # used for pgpool.conf file
        ports:
            - 5430:5432
            - 9898:9898 # PCP
        networks:
            cluster:
                aliases:
                    - pgpool
volumes:
    pgmaster:
    pgslave1:
    backup:

```