5 - CentOS system configuration before k8s installation

Prerequisites:

Node	OS	IP
k8s-master	CentOS7	192.168.137.161
k8s-node1	CentOS7	192.168.137.162

Now we have 2 working CentOS virtual machine, which can connect to each other, also able access to Internet. Let's do some configuration before we provision kubernetes cluster on them.

Install kubernetes:

1. Disable firewall for both master and node by running below command
   

   firewall-cmd --state                          # check firewall state
   systemctl stop firewalld.service         # stop firewall
   systemctl disable firewalld.service     # disable firewall to auto launch

   
2. Update iptables
   Running below command to setting iptables for both master and node
   

   cat <<EOF > /etc/sysctl.d/kubernetes.conf
   net.bridge.bridge-nf-call-ip6tables = 1
   net.bridge.bridge-nf-call-iptables = 1
   EOF
   
   sysctl --system

   

3. Disable SELinux module for both master and node by running below command
   

   getenforce                    # check SELinux status
   setenforce 0                  # stop SELinux
   sed -i "s/SELINUX\=.*/SELINUX=disable/g" /etc/selinux/config          # disable SELinux module
   
   shutdown -r now               # Reboot system is required

   
4. Update host name
   Execute below command for master node:
   

   more /etc/hostname        # check current hostname
   hostnamectl set-hostname master01        # update hostname to master01

   
   

   Perform the same command to update hostname of k8s-node1:

   
5. Modify hosts file /etc/hosts on both node k8s-master and k8s-node1
   Execute below command to append host details to the end of file /etc/hosts:
   

   cat >> /etc/hosts << EOF
   192.168.137.161    master01
   192.168.137.162    node01

   

    NOTE: Perform the same update for k8s-node1
   

6. Disable swap
   Run below commands swapoff -a on both k8s-master and k8s-node1:
   

   sed -i '/swap/d' /etc/fstab
   swapoff -a        # switch of swap temporary
   free -m           # check if swap turned off successful, the line swap should be showing 0

   
7. Setting up yum resource for both nodes
   Since some of external site been blocked, so we need to repoint yum source to domestic agent resource, running below command to setup:
   

   cat <<EOF > /etc/yum.repos.d/kubernetes.repo
   [kubernetes]
   name=Kubernetes
   baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
   enabled=1
   gpgcheck=0
   repo_gpgcheck=0
   gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
   EOF

   
8. Execute below commands on both nodes, refresh yum cache
   

   yum clean all
   yum -y makecache

   
9. All set for system configuration now. We are ready to provision container and Kubernetes !
   Next let's get Docker installed from both master01 and node1.