ETCD database cluster certificate renewal for Kubernets external database setup

I used these steps to renew the certs on kubernets cluster v1.18.6.

1. compile the etcdadm cert branch code

   git clone -b cert https://github.com/pytimer/etcdadm.git
    cd  etcdadm
    docker run --rm -it -v "$PWD":/etcdadm  golang bash
    cd /etcdadm
    make
    cp etcdadm etcdadm-cert 
   

2. copy etcdadm-cert file to all three server.

3. Renew the cert on first master

   /opt/bin/etcdadm-cert certs renew kubeadm alpha certs renew all

4. Reboot the first master

5. check the etcd member and kubernetes certificate expire data

Repeated step 2 to 5 on ther master nodes

use these commands to validate

/opt/bin/etcdctl.sh   member list
kubeadm alpha certs check-expiration

Thanks SR