Kubernetes : Install Kubeadm2022/11/22

Install Kubeadm to Configure Multi Nodes Kubernetes Cluster.

This example is based on the environment like follows.

For System requirements, each Node has unique Hostname, MAC address, Product_uuid.
MAC address and Product_uuid are generally already unique one if you installed OS on physical machine or virtual machine with common procedure.
You can see Product_uuid with the command [dmidecode -s system-uuid].

Furthermore, it based on the environment Firewalld is disabled.

-----------+---------------------------+--------------------------+------------
           |                           |                          |
       eth0|10.0.0.30              eth0|10.0.0.51             eth0|10.0.0.52
+----------+-----------+   +-----------+----------+   +-----------+----------+
|   [ dlp.srv.world ]  |   | [ node01.srv.world ] |   | [ node02.srv.world ] |
|     Control Plane    |   |      Worker Node     |   |      Worker Node     |
+----------------------+   +----------------------+   +----------------------+

[1]	On all Nodes, Change settings for System requirements.

[root@dlp ~]#

cat > /etc/sysctl.d/99-k8s-cri.conf <<EOF
net.bridge.bridge-nf-call-iptables=1
net.ipv4.ip_forward=1
net.bridge.bridge-nf-call-ip6tables=1
EOF

[root@dlp ~]#

echo -e overlay\\nbr_netfilter > /etc/modules-load.d/k8s.conf

[root@dlp ~]#

dnf -y install iptables-legacy

[root@dlp ~]#

alternatives --config iptables


There are 2 programs which provide 'iptables'.

  Selection    Command
-----------------------------------------------
*+ 1           /usr/sbin/iptables-nft
   2           /usr/sbin/iptables-legacy

# switch to [iptables-legacy]
Enter to keep the current selection[+], or type selection number: 2

# set Swap off setting

[root@dlp ~]#

touch /etc/systemd/zram-generator.conf

# switch to Cgroup v1 (default is v2)

[root@dlp ~]#

grubby --update-kernel ALL --args systemd.unified_cgroup_hierarchy=0

# disable [firewalld]

[root@dlp ~]#

systemctl disable --now firewalld

# disable [systemd-resolved] (enabled by default)

[root@dlp ~]#

systemctl disable --now systemd-resolved

[root@dlp ~]#

vi /etc/NetworkManager/NetworkManager.conf

# add into [main] section

[main]

dns=default

[root@dlp ~]#

unlink /etc/resolv.conf

[root@dlp ~]#

touch /etc/resolv.conf

# restart to apply changes

[root@dlp ~]#

reboot

[2]	On all Nodes, Install required packages. This example shows to use CRI-O for container runtime.

[root@dlp ~]#

dnf module -y install cri-o:1.24/default

[root@dlp ~]#

systemctl enable --now crio

[root@dlp ~]#

dnf -y install kubernetes-kubeadm kubernetes-node kubernetes-client cri-tools iproute-tc container-selinux

[root@dlp ~]#

vi /etc/kubernetes/kubelet

# line 5 : change

KUBELET_ADDRESS="--address=

0.0.0.0

# line 8 : uncomment

KUBELET_PORT="--port=10250"

# line 11 : change to your hostname

KUBELET_HOSTNAME="--hostname-override=

dlp.srv.world

[root@dlp ~]#

vi /etc/systemd/system/kubelet.service.d/kubeadm.conf

# line 6 : add

Environment="KUBELET_EXTRA_ARGS=--cgroup-driver=systemd

--container-runtime=remote --container-runtime-endpoint=unix:///var/run/crio/crio.sock

[root@dlp ~]#

systemctl enable kubelet

[3]	On all Nodes, if SELinux is enabled, change policy.

[root@dlp ~]#

vi k8s.te

# create new

module k8s 1.0;

require {
        type cgroup_t;
        type iptables_t;
        class dir ioctl;
}

#============= iptables_t ==============
allow iptables_t cgroup_t:dir ioctl;

[root@dlp ~]#

checkmodule -m -M -o k8s.mod k8s.te

[root@dlp ~]#

semodule_package --outfile k8s.pp --module k8s.mod

[root@dlp ~]#

semodule -i k8s.pp

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