Kubedm series-00-overview

Overview

Kubernetes 1.24 Is officially abandoned
Dockershim Version of , This article mainly describes the installation Kubernetes 1.24 + containerd 1.6.6 As CRI The cluster of , It is mainly installed in the way of package manager , The installation process can also be referred to Official documents

Software	edition	other
kubernetes	1.24.1
containerd	1.6.6
runc	1.1.2
Centos	8 Stream
kernel	5.18.5-1.el8.elrepo.x86_64

To configure yum repo file

stay 1.24 Version of , When installing, you may encounter this strange problem , gpgcheck=0 repo_gpgcheck=0 Just turn off these two parameters

cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo [kubernetes] name=Kubernetes baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-\$basearch enabled=1 gpgcheck=0 repo_gpgcheck=0 gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg exclude=kubelet kubeadm kubectl EOF

#  Domestic sources can also 
cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo [kubernetes] name=Kubernetes baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64 enabled=1 gpgcheck=0 repo_gpgcheck=0 gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg EOF

Configuration of machine initialization

If it is a public cloud , These configurations may be related to some software and images of the public cloud's own machine and system initialization , So the following commands are not not always 100% whole
, Of course , If you lack any software or configuration , Carry out later kubeadm init You'll find out

# Set SELinux in permissive mode (effectively disabling it)
sudo setenforce 0
sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config
#  Turn off firewall 
systemctl stop firewalld && systemctl disable firewalld
sysctl -w net.ipv4.ip_forward=1
echo 1 > /proc/sys/net/bridge/bridge-nf-call-iptables
echo 1 > /proc/sys/net/ipv4/ip_forward
#  Loading kernel modules 
modprobe br_netfilter
modprobe overlay
#  Time synchronization 
yum install ntpdate -y
#  Easy to check ipvs The problem of 
yum install -y ipset ipvsadm

Software dependency

If no version is specified , With yum install kubeadm The operation of , The default is to find the latest , Therefore, it is recommended to install the specified version according to the following command

#  install 1.24.1
sudo yum install -y kubelet-1.24.1-0 kubeadm-1.24.1-0 kubectl-1.24.1-0 --disableexcludes=kubernetes
#  install 1.21.7
sudo yum install -y kubelet-1.21.7-0 kubeadm-1.21.7-0 kubectl-1.21.7-0 --disableexcludes=kubernetes
#  Delete 1.24.1
sudo yum remove -y kubelet-1.24.1-0 kubeadm-1.24.1-0 kubectl-1.24.1-0 --disableexcludes=kubernetes
#  Delete 1.21.7
sudo yum remove -y kubelet-1.21.7-0 kubeadm-1.21.7-0 kubectl-1.21.7-0 --disableexcludes=kubernetes

in addition , As a dependency , In the installation kubelet/kubeadm/kubectl When , The following software will also be installed , You also need to pay attention to the version , Don't have too big version differences , If it is installed in the way of package manager , Generally, these software versions correspond well

cri-tools.x86_64 0:1.24.0-0                    
kubernetes-cni.x86_64 0:0.8.7-0                    
socat.x86_64 0:1.7.3.2-2.el7

kubelet.service

Check it out. kubelet.service File structure , More common , But you need to know ,kubeadm Initialized cluster , The default is to use the kubelet As service To deploy , Unlike other components kube-apiserver/etcd In that way Static Pod Form operation

cat /etc/systemd/system/multi-user.target.wants/kubelet.service
[Unit]
Description=kubelet: The Kubernetes Node Agent
Documentation=https://kubernetes.io/docs/
Wants=network-online.target
After=network-online.target

[Service]
ExecStart=/usr/bin/kubelet
Restart=always
StartLimitInterval=0
RestartSec=10

[Install]
WantedBy=multi-user.target

kubeadm init

actually kubeadm init Will do a lot of configuration checks , For example, it will check cri runtime What is it? Wait a minute , Or set the host name

#  Set host name 
hostnamectl set-hostname master

Mirror image problem

In the domestic public cloud environment , Image download stuck , In fact, you can execute the following command to confirm , If ps -ef Take a look , The following process cannot be mirrored in China , So think about the configuration

kubeadm config images pull --kubernetes-version 1.24.1
#  use crictl download 
/usr/bin/crictl -r unix:///var/run/containerd/containerd.sock pull k8s.gcr.io/kube-apiserver:v1.24.1

Containerd Common configuration of

#  Two must be replaced endpoint, This operation can also be modified directly kubeadm Initialization profile for 
crictl config runtime-endpoint unix:///run/containerd/containerd.sock
crictl config image-endpoint unix:///run/containerd/containerd.sock
#  Test it 
crictl pull docker.io/library/redis:alpine3.13
#  Replace it with a domestic image 

Look at the mirror image

Be careful ctr To view the image, you need to bring namespace Of

ctr --namespace k8s.io images list

Make this problem to the extent that the business has to solve

If there is any problem during the installation , please Look carefully kube init The following command output , The other is to check kubelet as well as containerd Logs of these two services , The following are the possible troubleshooting commands

journalctl -xeu containerd --no-page -f
journalctl -xeu kubelet --no-page -f

Modify the certificate

We can refer to post

perform

In the face of kubeadm In the analysis , The author mainly refers to two major editions , Namely Kubernetes 1.21.7 as well as Kubernetes 1.24.1, Old irons are reading , If in doubt , You can download these two versions of code for reference , If not specially marked , Generally speaking, it means Kubernetes 1.24.1 Code for

Below kubeadm init Log , Some personal information is omitted , And added some step notes , Relevant information can also be obtained through kubeadm init --help Command to print out

#  Created k8s edition 
[init] Using Kubernetes version: v1.24.1
#  Enter from here preflight The stage of 
[preflight] Running pre-flight checks
	[WARNING SystemVerification]: missing optional cgroups: blkio
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
#  Enter the certificate stage from here 
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [ip-172-31-90-126 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 172.31.90.126]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [ip-172-31-90-126 localhost] and IPs [172.31.90.126 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [ip-172-31-90-126 localhost] and IPs [172.31.90.126 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "sa" key and public key
#  Get into kubeconfig The stage of 
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
#  To start kubelet
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Starting the kubelet
#  Start controlplane The start-up phase 
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
#  health examination 
[apiclient] All control plane components are healthy after 16.503764 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
#  to controlplane Put on the necessary label
[mark-control-plane] Marking the node ip-172-31-90-126 as control-plane by adding the labels: [node-role.kubernetes.io/control-plane node.kubernetes.io/exclude-from-external-load-balancers]
[mark-control-plane] Marking the node ip-172-31-90-126 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule node-role.kubernetes.io/control-plane:NoSchedule]
#  establish token
[bootstrap-token] Using token: qlk4br.83yi47aqacj3cwzh
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to get nodes
[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] Configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] Configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
#  The stage of plug-in installation 
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

The following is the log of successful installation after the above process , Will prompt you to kubeconig Configure it

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

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

Alternatively, if you are the root user, you can run:

  export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster.
Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:
  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 172.31.90.126:6443 --token qlk4br.83yi47aqacj3cwzh \
	--discovery-token-ca-cert-hash sha256:cc121a0e581abbdedcbad370077c46e11da9d6ea60a201dd54be4c70893f98f4

In fact, for kubeadm The understanding of the , I think so , He did a lot of scripted work , Thanks to go Relatively rich toolkits bound to the system , So it will be very convenient to call , The other is to use actually , All these inspections and installation work , Using scripts shell And the like can also be written well , Actually, I used to do Kubernetes 1.8 And previous versions , Deployment is done with scripts written by operation and maintenance , There is not much difference in essence , But with go To write , You can add some scalability and robustness , This is something considered from the grammatical level