fix warning:

1.[WARNING Firewalld]: firewalld is active, please ensure ports [6443 10250] are open or your cluster may not function correctly

answer: systemctl stop firewalld.service

2.[WARNING Service-Docker]: docker service is not enabled, please run ‘systemctl enable docker.service’

Systemctl enable docker.service

answer: systemctl enable docker.service

3.[WARNING IsDockerSystemdCheck]: detected “cgroupfs” as the Docker cgroup driver. The recommended driver is “systemd”. Please follow the guide at https://kubernetes.io/docs/setup/cri/

a:

official documentation indicates that changing the Settings so that the container runtime and kubelet use systemd as the cgroup driver makes the system more stable. Notice that under Docker, you set the option native. Cgroupdriver = Systemd.

two solutions:

1. Edit docker configuration file /etc/docker/daemon.json

1 2 3

“exec-opts”: [“native.cgroupdriver=systemd”] systemctl daemon-reload systemctl restart docker

2, edit the/usr/lib/systemd/system/docker. Service

1 2 3

ExecStart=/usr/bin/dockerd -H fd:// –containerd=/run/containerd/containerd.sock –exec-opt native.cgroupdriver=systemd systemctl daemon-reload systemctl restart docker

command:

vi /usr/lib/systemd/system/docker.service

–exec-opt native. Cgroupdriver =systemd (append)

After setting

, you can see that the Cgroup Driver is systemd

through the docker info command

1	docker info | grep Cgroup

4.[WARNING FileExisting-tc]: tc not found in system path

solution:

cannot be installed with yum, yum has a version, but has been unable to load down.

can be installed with yum, yum server is also this version:

yum command: yum install tc-y

note: the version is very important. I tried several versions. Only 5.3.0-1 works

download RPM package:

http://mirror.centos.org/centos/8/BaseOS/x86_64/os/Packages/iproute-tc-5.3.0-1.el8.x86_64.rpm

local installation:

yum localinstall – y iproute – tc – 5.3.0-1 RPM el8. X86_64.

5.[WARNING Hostname]: hostname “master” could not be reached

solution: see 6

6.[WARNING Hostname]: hostname “master”: lookup master on [fe80::1%ens33]:53: read udp [fe80::e0c:1711:9797:f6c7%ens33]:56921-> [fe80::1%ens33]:53: i/o timeout
error execution phase preflight: [preflight] Some fatal errors occurred:

solution:

The

command changes the host name

hostnamectl set-hostname k8s

change/etc/hostname

echo k8s > /etc/hostname

modifies the example

cat > > /etc/hosts < < EOF
192.168.100.4 master
192.168.100.5 node1
192.168.100.6 node2
EOF

, where IP is the address of the master node and the node node assigned to you

cleanup command:

sudo kubeadm reset

if

$kubeadm init \
– apiserver – advertise – address = 192.168.44.146 \
– image – repository registry.aliyuncs.com/google_containers \
– kubernetes – version v1.18.0 \
– service – cidr = 10.96.0.0/12 \
– pod – network – cidr = 10.244.0.0/16

that’s the step that’s going to go wrong, that’s the easiest step to go wrong. Master can’t boot up alive, so you can use this command.

caution, the test is nothing, it will not kill you (k8s) I am still a vegetable chicken, not only this command will bring side effects, but when the test, to solve the problem, it really works!

docker system prune -a

can be used to clean up disks, remove closed containers, useless data volumes, and networks