OKD - Create a Homelab OKD Cluster - Keepalived

We'll be working on the Servers that are surrounded by the continous lines in this drawing:

Keepalived is a useful tool to share a single Virtual IP (VIP) between multiple nodes without dealing with pacemaker, corosync and fencing. Keepalived is also fairly lightweight and easy to configure, so a good fit four this setup.

Start by installing keepalived:

 [archy@helper01 ~]$ sudo dnf -4y --refresh install keepalived  
 [archy@helper02 ~]$ sudo dnf -4y --refresh install keepalived  

After the packages are done installing, configure keepalived on the first helper node:

 [archy@helper01 ~]$ sudo vim /etc/keepalived/keepalived.conf  

 ! Configuration File for keepalived  
 global_defs {  
   notification_email {  
     admins@archyslife.lab  
   }  
   notification_email_from root@helper01.okd.archyslife.lab  
   smtp_server 127.0.0.1  
   smtp_connect_timeout 30  
   script_user root root  
 }  
 vrrp_script chk_haproxy {  
   script '/usr/bin/pidof haproxy'  
   interval 2  
 }  
 vrrp_instance VI_1 {  
   state MASTER  
   interface enp1s0  
   priority 100  
   virtual_router_id 51  
   unicast_src_ip 172.31.10.173  
   unicast_peer {  
      }  
   authentication {  
     auth_type PASS  
     auth_pass 8-character-secret-here  
   }  
   track_script {  
     chk_haproxy  
   }  
   virtual_ipaddress {  
     172.31.10.240  
   }  
 }  

Restart keepalived on the first node to check if the keepalived configuration works as expected. If the check returns with rc 0, the node will be considered eligible for the virtual ip address (172.31.10.240)

 [archy@helper01 ~]$ sudo systemctl enable --now keepalived.service  

Check for IP Addresses:

 [archy@helper01 ~]$ ip -s -c -h -4 addr show enp1s0  

 2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000  
   inet 172.31.10.173/24 brd 172.31.10.255 scope global dynamic noprefixroute enp1s0  
     valid_lft 223503sec preferred_lft 223503sec  
   inet 172.31.10.240/32 scope global enp1s0  
     valid_lft forever preferred_lft forever  
   RX: bytes packets errors dropped missed  mcast        
      33.5G  44.9M   0    1    0    0   
   TX: bytes packets errors dropped carrier collsns        
      33.4G  44.5M   0    0    0    0   

Okay, so the IP has been successfully assigned. The Configuration is correct and we can configure the next helper node.

Keepalived has already been installed in a previous step so we'll start with the configuration here:

 [archy@helper02 ~]$ sudo vim /etc/keepalived/keepalived.conf  

 ! Configuration File for keepalived  
 global_defs {  
   notification_email {  
     admins@archyslife.lab  
   }  
   notification_email_from root@helper02.okd.archyslife.lab  
   smtp_server 127.0.0.1  
   smtp_connect_timeout 30  
   script_user root root  
 }  
 vrrp_script chk_haproxy {  
   script '/usr/bin/pidof haproxy'  
   interval 2  
 }  
 vrrp_instance VI_1 {  
   state BACKUP  
   interface enp1s0  
   priority 100  
   virtual_router_id 51  
   unicast_src_ip 172.31.10.178  
   unicast_peer {  
      }  
   authentication {  
     auth_type PASS  
     auth_pass 8-character-secret-here  
   }  
   track_script {  
     chk_haproxy  
   }  
   virtual_ipaddress {  
     172.31.10.240  
   }  
 }  

Restart and enable keepalived.service to ensure it starts at next boot and the configuration is correct:

 [archy@helper02 ~]$ sudo systemctl enable --now keepalived.service  

For additional information, the logs of keepalived can be checked using 'journalctl -b -u keepalived.service'. However, this should be all there is to set up for keepalived in that scenario.

Feel free to comment and / or suggest a topic.