gistfile1.txt

Node 1:
vrrp_script check_openvpn {
  script    "/usr/bin/killall -0 openvpn"
  interval  5
  weight    2
}

vrrp_instance VI_52 {
  interface                 eth0
  state                     EQUAL
  virtual_router_id         52
  priority                  100
  advert_int                1
  garp_master_delay         5

  # notify scripts and alerts are optional
  #
  # filenames of scripts to run on transitions
  # can be unquoted (if just filename)
  # or quoted (if has parameters)

  authentication {
    auth_type PASS
    auth_pass PASSWORD
  }

  track_script {
    check_openvpn
  }

  virtual_ipaddress {
    10.100.11.106 dev eth0
  }

  unicast_src_ip 10.100.11.107

  unicast_peer {
    10.100.11.108
  }
  
  # for ANY state transition.
  # "notify" script is called AFTER the
  # notify_* script(s) and is executed
  # with 3 arguments provided by keepalived
  # (ie don’t include parameters in the notify line).
  # arguments
  # $1 = "GROUP"|"INSTANCE"
  # $2 = name of group or instance
  # $3 = target state of transition
  #     ("MASTER"|"BACKUP"|"FAULT")
  notify /usr/local/sbin/notify.sh
}

Node 2:
vrrp_script check_openvpn {
  script    "/usr/bin/killall -0 openvpn"
  interval  5
  weight    2
}

vrrp_instance VI_52 {
  interface                 eth0
  state                     EQUAL
  virtual_router_id         52
  priority                  100
  advert_int                1
  garp_master_delay         5

  # notify scripts and alerts are optional
  #
  # filenames of scripts to run on transitions
  # can be unquoted (if just filename)
  # or quoted (if has parameters)

  authentication {
    auth_type PASS
    auth_pass PASSWORD
  }

  track_script {
    check_openvpn
  }

  virtual_ipaddress {
    10.100.11.106 dev eth0
  }

  unicast_src_ip 10.100.11.108

  unicast_peer {
    10.100.11.107
  }
  
  # for ANY state transition.
  # "notify" script is called AFTER the
  # notify_* script(s) and is executed
  # with 3 arguments provided by keepalived
  # (ie don’t include parameters in the notify line).
  # arguments
  # $1 = "GROUP"|"INSTANCE"
  # $2 = name of group or instance
  # $3 = target state of transition
  #     ("MASTER"|"BACKUP"|"FAULT")
  notify /usr/local/sbin/notify.sh
}

On Dockerfile the CMD is as follow:
CMD['openvpn_run']

File: openvpn_run
#!/bin/sh

# Creates the folder for the tun0 interface
# needed by the OpenVPN
mkdir -p /dev/net
/usr/bin/mknod /dev/net/tun c 10 200

# Restores the iptables configuration
# By default it is ACCEPT everything
#/usr/sbin/iptables -A INPUT -p ICMP -j DROP

# Start keepalived
/usr/sbin/keepalived -f /etc/openvpn/keepalived.conf -l

# Starting the OpenVPN process
/usr/sbin/openvpn /etc/openvpn/server.conf