notes/divers/keepalived_on_docker_01.md

## DNS enteries:
```text
ivera-db1              IN A    192.168.0.109
ivera-db2              IN A    192.168.0.110
ivera-db-vip           IN A    192.168.0.115
```


## Master node

File `docker-compose.yml`:
```yml
services:
  keepalived:
    image: osixia/keepalived:latest
    container_name: keepalived-master
    restart: unless-stopped
    network_mode: host
    cap_add:
      - NET_ADMIN
      - NET_RAW
      - NET_BROADCAST
    volumes:
      - ./keepalived.conf:/etc/keepalived/keepalived.conf:ro
```

File `keepalived.conf`:
```text
vrrp_instance VI_1 {
    state MASTER
    interface enp1s0
    virtual_router_id 51
    priority 100
    advert_int 1
    
    unicast_src_ip 192.168.0.109    # Replace with Master node's actual IP
    unicast_peer {
        192.168.0.110               # Replace with Backup node's actual IP
    }

    authentication {
        auth_type PASS
        auth_pass secret
    }
    
    virtual_ipaddress {
        192.168.0.115/24           # The shared Virtual IP (VIP)
    }
}
```

## Backup node

File `docker-compose.yml`:
```yml
services:
  keepalived:
    image: osixia/keepalived:latest
    container_name: keepalived-backup
    restart: unless-stopped
    network_mode: host
    cap_add:
      - NET_ADMIN
      - NET_RAW
      - NET_BROADCAST
    volumes:
      - ./keepalived.conf:/etc/keepalived/keepalived.conf:ro
```

File `keepalived.conf`:
```text
vrrp_instance VI_1 {
    state BACKUP
    interface enp1s0
    virtual_router_id 51
    priority 90
    advert_int 1
    
    unicast_src_ip 192.168.0.110    # Replace with Backup node's actual IP
    unicast_peer {
        192.168.0.109               # Replace with Master node's actual IP
    }

    authentication {
        auth_type PASS
        auth_pass secret
    }
    
    virtual_ipaddress {
        192.168.0.115/24           # The shared Virtual IP (VIP)
    }
}
```