[LoadBalancing] Configure HAProxy and KeepAlived

apt install –y haproxy keepalived 

#/etc/keepalived/keepalived.conf 
---
vrrp_script chk_haproxy {
  script "killall -0 haproxy"
  interval 2
  weight 2
}

vrrp_instance vi_ip {
  state master
  priority 150
  interface ens3                      # Network card
  virtual_router_id 50
  advert_int 1
  authentication {
    auth_type HA
    auth_pass 1111
  }
  virtual_ipaddress {
    10.60.60.170/24 dev ens3        # The VIP address
  }

  track_script {
    chk_haproxy
  }
}
-------------- 
systemctl restart keepalived 

#/etc/keepalived/keepalived.conf 
---
vrrp_script chk_haproxy {
  script "killall -0 haproxy"
  interval 2
  weight 2
}

vrrp_instance vi_ip {
  state backup
  priority 100
  interface ens3                      # Network card
  virtual_router_id 50
  advert_int 1
  authentication {
    auth_type HA
    auth_pass 1111
  }
  virtual_ipaddress {
    10.60.60.170/24 dev ens3        # The VIP address
  }

  track_script {
    chk_haproxy
  }
}
-------------- 
systemctl restart keepalived

#/etc/haproxy/haproxy.cfg 
global 
    maxconn 100 

defaults 
    log global 
    mode tcp 
    retries 2 
    timeout client 30m 
    timeout connect 4s 
    timeout server 30m 
    timeout check 5s 

listen stats 
    mode http 
    bind *:9000 
    stats realm Haproxy\ 
    stats enable 
    stats uri / 
  
listen postgres 
    bind *:5000 
    option httpchk 
    http-check expect status 200 
    default-server inter 3s fall 3 rise 2 on-marked-down shutdown-sessions 
    server postgresql_10.60.60.87_db1 10.60.60.87:5432 maxconn 100 check port 8008 
    server postgresql_10.60.60.88_db2 10.60.60.88:5432 maxconn 100 check port 8008
    server postgresql_10.60.60.89_db3 10.60.60.89:5432 maxconn 100 check port 8008

frontend odoo-app 
    bind *:80 
    option tcplog 
    mode tcp 
    default_backend odoo-app-server 
  
backend odoo-app-server 
    mode tcp 
    balance roundrobin 
    option tcp-check 
    server web1 10.60.60.83:8069 check   
    server web2 10.60.60.84:8069 check backup
-------------- 
systemctl restart haproxy