CentOS 7 deployment k8s cluster

1. Version and planning

1.1 version information:

name	Version number
kernel	3.10.0-1160.el7.x86_64
operating system	CentOS Linux release 7.9.2009 (Core)
docker	20.10.11
kubeadm	1.23.0
kubelet	1.23.0
kubectl	1.23.0

1.2 cluster planning

IP	hostname
192.168.0.114	k8s-master
192.168.0.115	k8s-node01
192.168.0.116	k8s-node02

2 deployment

explain:

From step 1 to step 8, all nodes must operate
master node: steps 9 and 10
node: step 11

1. Turn off firewall

Close: systemctl stop firewalld
Permanent shutdown: systemctl disable firewalld

2. Close selinux

Close: setenforce0

3. Close swap

Temporary shutdown: swapoff -a
Permanently closed: sed - RI's /* swap.*/#&/' / Etc / fstab, comment out the code with swap lines through this command
Inspection: free -m

4. Add host name and IP correspondence

Add the mapping relationship in / etc/hosts according to the planning in 1.2

192.168.0.114 k8s-master
192.168.0.115 k8s-node01
192.168.0.116 k8s-node02

5. The chain that passes bridged IPV4 traffic to iptables

Add a configuration using the following command:

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

Execute the sysctl --system command to make the configuration effective:

6. Install docker

Installation:

wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo
yum install docker-ce

Set startup and self startup

systemctl start docker
systemctl enable docker

View version: docker version

Possible pits (skip here for the time being, and you can modify them later):

Problem: use the command docker info|grep cgroup to view. If the Cgroup Driver used by docker is cgroupfs. It may conflict with kubelet and need to be changed to consistent systemd
Solution 1: VI / etc / docker / daemon JSON, add the following code to the file and restart docker
```
{
	"exec-opts": ["native.cgroupdriver=systemd"]
}
```
Solution 2: you can also modify ExecStart in the docker startup service and add the parameter "-- exec opt native. Cgroupdriver = SYSTEMd"
```
# docker.service
vi /usr/lib/systemd/system/docker.service
# add to
ExecStart=/usr/bin/dockerd --exec-opt native.cgroupdriver=systemd
```

7. Add alicloud yum software source

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

Possible pits (skip here for the time being and come back later)

Problem: XXX may be prompted during installation RPM public key not installed

Solution 1: after importing the public key, reinstall it again

wget https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
wget https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
rpm --import yum-key.gpg
rpm --import rpm-package-key.gpg

Solution 2: kubernetes The configuration gpgchekc in the repo file is 0. You can do it without checking

8. Install kubedm, kubelet, kubectl

Install: Yum install -y kubelet-1.23 0 kubectl-1.23. 0 kubeadm-1.23. 0
Or install the latest: Yum install - y kubelet kubectl kubedm
Set startup and self startup: systemctl enable kubelet. Here, you only need to set startup. Because the configuration has not been completed, you do not need to start, and the start will not succeed

9. Initialize master node

Initialization command

kubeadm init \
--image-repository registry.aliyuncs.com/google_containers \
--kubernetes-version v1.23.0 \
--service-cidr=10.1.0.0/16 \
--pod-network-cidr=10.244.0.0/16

Parameter description
- --image-repository string
  - Choose a container registry to pull control plane images from (default "k8s.gcr.io")
  - Alicloud's registry is used here. Otherwise, it will be slow or even fail
If the installation fails, you need to clean up the environment with kubedm reset command before reinstalling.
Pit encountered:
- Question: The HTTP call equal to 'curl -sSL http://localhost:10248/healthz' failed with error: Get "http://localhost:10248/healthz": dial tcp [::1]:10248: connect: connection refused.
- Solution: see Step 6 for details

Initialization succeeded

If the following results appear, the initialization is successful

At the prompt, execute the following command

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

# The first command: to create a hidden folder kube
# The second command: copy the file admin Conf to this folder
# The third command: indicates the user and user group of the setting file

After executing the above commands, you can use the kubectl command. Otherwise, you will be prompted the connection to the server localhost: 8080 was rejected - did you specify the right host or port?

10. Install pod network plug-in (CNI)

GitHub address: https://github.com/flannel-io/flannel You can also download files directly

Install plug-ins:

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

Pit encountered
- Question: the connection to the server raw githubusercontent. com was refused - did you specify the right host or port?
- Solution: add raw.net in / etc/hosts githubusercontent. Com mapping. The ip address can be https://www.ipaddress.com View
Check whether the deployment is successful: kubectl get Pods - n Kube system
Check the node again and the status changes to ready

11. node join the cluster

To add a new node to the cluster, you only need to copy the kubedm join command after kubedm init is successfully executed in the master node to the node node to be added

kubeadm join 192.168.0.114:6443 --token whxbm2.x70y9k1feop2604b \
  --discovery-token-ca-cert-hash sha256:d4306836b7ef32fd802e559cf717bbbe3af6dd75d3cb2fa4d3db7a16cc25a657

After joining successfully, use the command kubectl get nodes on the master node to find that the node node has joined the cluster and its status is ready (wait a moment here)

Reference articles

Deployment of K8S cluster in CentOS7: https://www.cnblogs.com/caoxb/p/11243472.html

Keywords: Linux Docker Kubernetes

Added by claire on Mon, 13 Dec 2021 18:59:49 +0200

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