Kubernetes Starter: Use Kubeadm to build master, hands-on test no exception

This is the fifth day of my participation in the August More text Challenge. For details, see: August More Text Challenge

This column documented the process of installing k8S Master, which took two weeks, because the tutorials on Baidu were basically not working. The author promises that this article is easy to use, and it is recommended to collect.

1. Preparation

1. Check the environment

Swapoff -a // Disable swap setenforce 0 // Temporarily disable selinuxCopy the code

The following contents cannot be the same for each machine

Sudo cat/sys/class/dmi/id/product_uuid / / each machine at the same uuid cannot ifconfig - a / / IP cannot be the sameCopy the code

2. Open the port

3. Allow iptables to check bridge traffic

cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
br_netfilter
EOF
 
cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sudo sysctl --system
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2. Install

1. Install kubeadm, Kubectl, kubelet

Add mirror cat < < EOF | sudo tee/etc/yum repos. D/kubernetes. '[kubernetes] name = kubernetes baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64 enabled=1 gpgcheck=0 repo_gpgcheck=0 EOF # Sudo setenforce 0 sudo sed -i 's/^ SELinux =enforcing$/ SELinux =permissive/' sudo setenforce 0 sudo sed -i 's/^ SELinux =enforcing$/ SELinux =permissive/' /etc/selinux/config sudo yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes sudo systemctl enable Kubeadm version kubectl version --client kubelet --versionCopy the code

If the following information is displayed, the installation is successful and the installed version is visible.

2. Install the plug-in

yum -y install socat conntrack-tools
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3. Change the docker group to systemd

Docker needs to be installed in advance

sudo mkdir /etc/docker
cat <<EOF | sudo tee /etc/docker/daemon.json
{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
EOF
 
sudo systemctl enable docker
sudo systemctl daemon-reload
sudo systemctl restart docker
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4. K8s pull the required mirror

The kubeadm config images pull command can be used to download the image, but there is a high probability that the connection will fail, so use the Ali image command!

If v1.21.0 is used, the statement can be the same as the owner, otherwise, please pull it according to the above command.

Docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-controller-manager:v1.21.1 docker pull Registry.cn-hangzhou.aliyuncs.com/google_containers/kube-apiserver:v1.21.1 docker pull Registry.cn-hangzhou.aliyuncs.com/google_containers/kube-scheduler:v1.21.1 docker pull Registry.cn-hangzhou.aliyuncs.com/google_containers/kube-proxy:v1.21.1 docker pull Registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.4.1 docker pull Registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.4.13-0 docker pull coredns/coredns: 1.8.0 comes withCopy the code

When installing k8S, the image with the prefix k8s.gcr. IO will be obtained by default, so change the name of the image downloaded above.

Docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/kube-apiserver:v1.21.1 k8s. GCR. IO/kube - apiserver: v1.21.1 Docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/kube-proxy:v1.21.1 k8s. GCR. IO/kube - proxy: v1.21.1 docker The tag registry.cn-hangzhou.aliyuncs.com/google_containers/kube-controller-manager:v1.21.1 K8s. GCR. IO/kube - controller - manager: v1.21.1 docker tag Registry.cn-hangzhou.aliyuncs.com/google_containers/kube-scheduler:v1.21.1 k8s. GCR. IO/kube - the scheduler: v1.21.1 docker tag Registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.4.1 k8s. GCR. IO/pause: 3.4.1 track docker tag coredns/coredns: 1.8.0 comes with K8s. GCR. IO/coredns/coredns: v1.8.0 docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.4.13-0 K8s. GCR. IO/etcd: 3.4.13-0Copy the code

5. Install and start

1. Modify the host mapping

vi /etc/hosts
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2. Initialize the service

Kubeadm init --apiserver-advertise-address=192.168.44.15 -- pod-neto-cidr =10.244.0.0/16 --kubernetes-version=v1.21.1 |tee kubeadmin-init.logCopy the code

The following message is displayed: Initialization succeeded

3. Pay attention to

To make kubectl available to non-root users, run the following commands, which are also part of the kubeadm init output:

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
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Or, if you are root, you can run:

export KUBECONFIG=/etc/kubernetes/admin.conf
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If you want to reinitialize, you can perform kubeadm reset.

6. Installation of flannel

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
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If there is a Connecting to raw.githubusercontent.com refused, can perform vi/etc/hosts add 199.232.96.133 behind raw.githubusercontent.com

7. Verify

kubectl get nodes
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If ready is displayed, the installation is complete and the Master node has been registered with k8S.

8. Exception handling

If NotReady is present, you can run the following statement to determine the server status.

kubectl get nodes -o yaml
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Message: Docker: Network plugin is not ready: CNI Config uninitialized

If the preceding problems occur, view logs.

journalctl -f -u kubelet.service
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If the following log appears.

"Error validating the CNI config list" configList = "{\ n \" name \ ": \" cbr0 \ ", \ n \ "cniVersion \" : \ "0.3.1 \", \ n \ plugins \ "" : [\n {\n \"type\": \"flannel\",\n \"delegate\": {\n \"hairpinMode\": true,\n \"isDefaultGateway\": true\n }\n },\n {\n \"type\": \"portmap\",\n \"capabilities\": {\n \"portMappings\": true\n }\n }\n ]\n}\n" err="[failed to find plugin \"flannel\" in path [/opt/cni/bin] failed to find plugin \"portmap\" in path [/opt/cni/bin]]"Copy the code

Run the following command

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=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
yum clean all
yum install kubernetes-cni -y
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