k8s introduction and cluster construction and deployment

Kubernetes is an open source platform for automatic deployment, expansion and operation and maintenance of container clusters. With kubernetes, you can quickly and effectively respond to user needs; deploy your applications quickly and expectedly; expand your applications rapidly; seamlessly connect new application functions; save resources and optimize the use of hardware resources. It provides a complete open source solution for container choreography management.

• With the rapid development of Docker as a high-level container engine, in Google, container technology has been applied to
  For many years, Borg system is running and managing thousands of container applications.
• Kubernetes project originates from Borg, which can be said to be the essence of Borg design thought and absorb.
  The experiences and lessons of Borg system are presented.
• Kubernetes abstracts computing resources at a higher level by combining containers in detail,
  Deliver the final application service to the user.
• Benefits of Kubernetes:
  • Hidden resource management and error handling, users only need to pay attention to application development.
  • The service is highly available and reliable.
  • The load can be run in a cluster of thousands of machines.

k8s application, containerization deployment and binary deployment, there are many applications of containers.

The Kubernetes cluster contains node agent kubelet and Master components (APIs, scheduler, etcd,), all based on distributed storage system.

• Kubernetes is mainly composed of the following core components:

• in addition to the core components, there are some recommended add ons:

• Kubernetes design concept and function is actually a layered architecture similar to Linux

• ecosystem:
  • Kubernetes external: logging, monitoring, configuration management, CI, CD, Workflow, FaaS
    OTS application, ChatOps, etc
  • Kubernetes internal: CRI, CNI, CVI, image warehouse, Cloud Provider, cluster itself
    Configuration and management of

reference resources: https://kubernetes.io/zh/docs/setup/production-environment/tools/kubeadm/install-kubeadm/

Here we need to use harbor warehouse, because the speed of pulling from the local warehouse is faster than pulling from the Internet:

Environmental Science:
server1: 172.25.254.1 harbor warehouse
server2: 172.25.254.2 master node
server3: 172.25.254.3 node
server4: 172.25.254.4 node

On server2, 3, 4 hosts:
Turn off selinux and iptables firewall of the node

• All nodes deploy docker engine: deploy and install from Alibaba cloud.

# step 1: install some necessary system tools yum install -y yum-utils device-mapper-persistent-data lvm2 # Step 2: add software source information yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo # Step 3: update and install docker CE yum -y install docker-ce # Need container SELinux dependency

[root@server1 yum.repos.d]# cat /etc/sysctl.d/bridge.conf net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 # Kernel support. [root@server1 yum.repos.d]# scp /etc/sysctl.d/bridge.conf server2:/etc/sysctl.d/ [root@server1 yum.repos.d]# scp /etc/sysctl.d/bridge.conf server3:/etc/sysctl.d/ [root@server1 yum.repos.d]# scp /etc/sysctl.d/bridge.conf server4:/etc/sysctl.d/ # Let these two parameters take effect [root@server2 ~]# sysctl --system [root@server3 ~]# sysctl --system [root@server4 ~]# sysctl --system systemctl enable --now docker # Open the docker service of three nodes

• Change docker and k8s to use the same control method:

[root@server2 ~]# docker info Cgroup Driver: cgroupfs # docker was originally controlled by cgroup. We need to change it to systemd [root@server2 packages]# vim /etc/docker/daemon.json { "exec-opts": ["native.cgroupdriver=systemd"], "log-driver": "json-file", "log-opts": { "max-size": "100m" }, "storage-driver": "overlay2", "storage-opts": [ "overlay2.override_kernel_check=true" ] } [root@server2 packages]# scp /etc/docker/daemon.json server3:/etc/docker/ root@server3's password: daemon.json 100% 201 238.1KB/s 00:00 [root@server2 packages]# scp /etc/docker/daemon.json server4:/etc/docker/ root@server4's password: daemon.json [root@server2 packages]# systemctl restart docker Cgroup Driver: systemd # Became the way of systemd

• Disable swap partition:

#Disable swap partition for better performance [root@server3 ~]# swapoff -a #Server 2, 3, 4 [root@server3 ~]# vim /etc/fstab [root@server3 ~]# vim /etc/fstab [root@server3 ~]# cat /etc/fstab # # /etc/fstab # Created by anaconda on Tue Apr 28 02:35:30 2020 # # Accessible filesystems, by reference, are maintained under '/dev/disk' # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info # /dev/mapper/rhel-root / xfs defaults 0 0 UUID=004d1dd6-221a-4763-a5eb-c75e18655041 /boot xfs defaults 0 0 #/dev/mapper/rhel-swap swap swap defaults 0 0

• Install deployment software kubeadm:
  We download from Alibaba cloud:

[root@server2 yum.repos.d]# vim k8s.repo [kubernetes] name=Kubernetes baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/ enabled=1 gpgcheck=0 [root@server2 yum.repos.d]#yum install -y kubelet kubeadm kubectl # kubectl only needs to be installed in the master node

The other two nodes do the same operation.

[root@server2 yum.repos.d]# systemctl enable --now kubelet.service #View default configuration information imageRepository: k8s.gcr.io # The default value is k8s gcr.io You need to climb over the wall to download the component image, so you need to modify the image warehouse: [root@server2 yum.repos.d]# kubeadm config images list # List required mirrors W0618 15:03:59.486677 14931 configset.go:202] WARNING: kubeadm cannot validate component configs for API groups [kubelet.config.k8s.io kubeproxy.config.k8s.io] k8s.gcr.io/kube-apiserver:v1.18.4 k8s.gcr.io/kube-controller-manager:v1.18.4 k8s.gcr.io/kube-scheduler:v1.18.4 k8s.gcr.io/kube-proxy:v1.18.4 k8s.gcr.io/pause:3.2 k8s.gcr.io/etcd:3.4.3-0 k8s.gcr.io/coredns:1.6.7 # List in designated Alibaba cloud warehouse [root@server2 yum.repos.d]# kubeadm config images list --image-repository registry.aliyuncs.com/google_containers W0618 15:04:21.098999 14946 configset.go:202] WARNING: kubeadm cannot validate component configs for API groups [kubelet.config.k8s.io kubeproxy.config.k8s.io] registry.aliyuncs.com/google_containers/kube-apiserver:v1.18.4 registry.aliyuncs.com/google_containers/kube-controller-manager:v1.18.4 registry.aliyuncs.com/google_containers/kube-scheduler:v1.18.4 registry.aliyuncs.com/google_containers/kube-proxy:v1.18.4 registry.aliyuncs.com/google_containers/pause:3.2 registry.aliyuncs.com/google_containers/etcd:3.4.3-0 registry.aliyuncs.com/google_containers/coredns:1.6.7 [root@server2 yum.repos.d]# kubeadm config images pull --image-repository registry.aliyuncs.com/google_containers --kubernetes-version=1.18.3 # Pull image [root@server2 yum.repos.d]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE registry.aliyuncs.com/google_containers/kube-proxy v1.18.3 3439b7546f29 4 weeks ago 117MB registry.aliyuncs.com/google_containers/kube-apiserver v1.18.3 7e28efa976bd 4 weeks ago 173MB registry.aliyuncs.com/google_containers/kube-controller-manager v1.18.3 da26705ccb4b 4 weeks ago 162MB registry.aliyuncs.com/google_containers/kube-scheduler v1.18.3 76216c34ed0c 4 weeks ago 95.3MB registry.aliyuncs.com/google_containers/pause 3.2 80d28bedfe5d 4 months ago 683kB registry.aliyuncs.com/google_containers/coredns 1.6.7 67da37a9a360 4 months ago 43.8MB registry.aliyuncs.com/google_containers/etcd 3.4.3-0 303ce5db0e90 7 months ago 288MB

Then we put these images into the harbor warehouse for our other nodes to pull.

[root@server1 yum.repos.d]# scp -r /etc/docker/certs.d/ server2:/etc/docker/ root@server2's password: # Give the certificate of harbor to server2 ca.crt [root@server2 yum.repos.d]# vim /etc/hosts [root@server2 yum.repos.d]# cat /etc/hosts 172.25.254.1 server1 reg.caoaoyuan.org # Analyze the harbor warehouse. [root@server2 yum.repos.d]# docker login reg.caoaoyuan.org Username: admin Password: Login Succeeded # Log in [root@server2 ~]# docker images |grep reg.ca | awk '' reg.caoaoyuan.org/library/kube-proxy:v1.18.3 #Label the image above like this. reg.caoaoyuan.org/library/kube-apiserver:v1.18.3 reg.caoaoyuan.org/library/kube-controller-manager:v1.18.3 reg.caoaoyuan.org/library/kube-scheduler:v1.18.3 reg.caoaoyuan.org/library/pause:3.2 reg.caoaoyuan.org/library/coredns:1.6.7 reg.caoaoyuan.org/library/etcd:3.4.3-0 # Upload to harbor warehouse [root@server2 ~]# for i in `docker images |grep reg.ca | awk ''`;do dicker push $i ;done # Delete Alibaba cloud image [root@server2 ~]# for i in `docker images |grep regis | awk ''`;do docker rmi $i ;done

Upload succeeded. Other nodes can be pulled. Pay attention to putting the certificate first and local parsing:

[root@server1 harbor]# scp -r /etc/docker/certs.d/ server3:/etc/docker/ root@server3's password: ca.crt 100% 2114 39.7KB/s 00:00 [root@server1 harbor]# scp -r /etc/docker/certs.d/ server4:/etc/docker/ root@server4's password: ca.crt # These two nodes have not been placed

Perform cluster initialization at the master node:

[root@server2 ~]# kubeadm init --pod-network-cidr=10.244.0.0/16 --image-repository reg.caoaoyuan.org/library/ Your Kubernetes control-plane has initialized successfully! --kubernetes-version=1.18.3 kubeadm join 172.25.254.2:6443 --token 61xkmb.qd1alzh6winolaeg \ --discovery-token-ca-cert-hash sha256:ef9f8d0f0866660e7a01c54ecfc65abbbb11f25147ec7da75453098a9302e597 //The token (used to join the cluster) and hash code (used to verify the master side) are generated. The token is saved 24H by default [kubeadm@server2 ~]$ kubeadm token list TOKEN TTL EXPIRES USAGES DESCRIPTION EXTRA GROUPS 61xkmb.qd1alzh6winolaeg 23h 2020-06-19T17:31:47+08:00 authentication,signing The default bootstrap token generated by 'kubeadm init'. system:bootstrappers:kubeadm:default-node-token # After expiration, you can use kubeadm token create to generate.

The official suggestion is that we use ordinary user operation cluster. We only need to:

[root@server2 ~]# useradd kubeadm [root@server2 ~]# visudo # Delegate authority to kubeadm su[root@server2 ~]# su - kubeadm [kubeadm@server2 ~]$ mkdir -p $HOME/.kube [kubeadm@server2 ~]$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config #It's actually a certificate. #Put the authentication over and you can manipulate the cluster [kubeadm@server2 ~]$ sudo chown $(id -u):$(id -g) $HOME/.kube/config [kubeadm@server2 ~]$ kubectl get node NAME STATUS ROLES AGE VERSION server2 NotReady master 12m v1.18.3 #Currently, there are only master nodes and they are not ready

Expand the capacity of the node, add server3 and server4 to server2:

sysctl -w net.ipv4.ip_forward=1 #You may need to execute this command [root@server4 ~]# kubeadm join 172.25.254.2:6443 --token 61xkmb.qd1alzh6winolaeg --discovery-token-ca-cert-hash sha256:ef9f8d0f0866660e7a01c54ecfc65abbbb11f25147ec7da75453098a9302e597 [root@server3 ~]# kubeadm join 172.25.254.2:6443 --token 61xkmb.qd1alzh6winolaeg --discovery-token-ca-cert-hash sha256:ef9f8d0f0866660e7a01c54ecfc65abbbb11f25147ec7da75453098a9302e597 [kubeadm@server2 ~]$ kubectl get nodes NAME STATUS ROLES AGE VERSION server2 NotReady master 20m v1.18.3 server3 NotReady <none> 88s v1.18.3 server4 NotReady <none> 31s v1.18.3 # There are two nodes added.

• To install the flannel network components:

[root@server2 demo]# docker images quay.io/coreos/flannel v0.12.0-amd64 4e9f801d2217 3 months ago 52.8MB # Import this network component at both nodes 3 and 4 # Switch to kubeadm user to apply this file. [kubeadm@server2 ~]$ kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml podsecuritypolicy.policy/psp.flannel.unprivileged created clusterrole.rbac.authorization.k8s.io/flannel created clusterrolebinding.rbac.authorization.k8s.io/flannel created serviceaccount/flannel created configmap/kube-flannel-cfg created daemonset.apps/kube-flannel-ds-amd64 created daemonset.apps/kube-flannel-ds-arm64 created daemonset.apps/kube-flannel-ds-arm created daemonset.apps/kube-flannel-ds-ppc64le created daemonset.apps/kube-flannel-ds-s390x created [kubeadm@server2 ~]$ kubectl get pod -n kube-system #, system components whose pod s are all isolated in the way of namespace NAME READY STATUS RESTARTS AGE coredns-5fd54d7f56-22fwz 1/1 Running 0 123m coredns-5fd54d7f56-l9z5k 1/1 Running 0 123m etcd-server2 1/1 Running 3 124m kube-apiserver-server2 1/1 Running 2 124m kube-controller-manager-server2 1/1 Running 3 124m kube-flannel-ds-amd64-6t4tp 1/1 Running 0 9m31s kube-flannel-ds-amd64-gk9r2 1/1 Running 0 9m31s # Network components kube-flannel-ds-amd64-mlcvm 1/1 Running 0 9m31s kube-proxy-f7rnh 1/1 Running 0 104m kube-proxy-hww5t 1/1 Running 1 104m kube-proxy-wn4h8 1/1 Running 3 123m kube-scheduler-server2 1/1 Running 3 124m # It's all running [kubeadm@server2 ~]$ kubectl get nodes NAME STATUS ROLES AGE VERSION server2 Ready master 125m v1.18.3 server3 Ready <none> 106m v1.18.3 server4 Ready <none> 105m v1.18.3 #ready # We can use this cluster

• View namespace

[kubeadm@server2 ~]$ kubectl get pod --all-namespaces #View all namespaces [kubeadm@server2 ~]$ kubectl get pod -o wide -n kube-system # -o wide view details NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES coredns-5fd54d7f56-22fwz 1/1 Running 0 3h34m 10.244.2.2 server4 <none> <none> coredns-5fd54d7f56-l9z5k 1/1 Running 0 3h34m 10.244.1.2 server3 <none> <none> etcd-server2 1/1 Running 3 3h34m 172.25.254.2 server2 <none> <none> kube-apiserver-server2 1/1 Running 2 3h34m 172.25.254.2 server2 <none> <none> kube-controller-manager-server2 1/1 Running 3 3h34m 172.25.254.2 server2 <none> <none> kube-flannel-ds-amd64-6t4tp 1/1 Running 0 100m 172.25.254.3 server3 <none> <none> kube-flannel-ds-amd64-gk9r2 1/1 Running 0 100m 172.25.254.2 server2 <none> <none> kube-flannel-ds-amd64-mlcvm 1/1 Running 0 100m 172.25.254.4 server4 <none> <none> kube-proxy-f7rnh 1/1 Running 0 3h14m 172.25.254.4 server4 <none> <none> kube-proxy-hww5t 1/1 Running 1 3h15m 172.25.254.3 server3 <none> <none> kube-proxy-wn4h8 1/1 Running 3 3h34m 172.25.254.2 server2 <none> <none> kube-scheduler-server2 1/1 Running 3 3h34m 172.25.254.2 server2 <none> <none> //You can see where these components are running. The flannel component uses the controller of dameset. Its characteristic is that each node runs one. proxy There are also at each node. [root@server4 ~]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE reg.caoaoyuan.org/library/kube-proxy v1.18.3 3439b7546f29 4 weeks ago 117MB quay.io/coreos/flannel v0.12.0-amd64 4e9f801d2217 3 months ago 52.8MB reg.caoaoyuan.org/library/pause 3.2 80d28bedfe5d 4 months ago 683kB reg.caoaoyuan.org/library/coredns 1.6.7 67da37a9a360 4 months ago 43.8MB server3 and server4 Join the cluster and get harbor The warehouse information pulls these images, kubernete It is ready to run. All services are run as containers.

• Auto complement

[kubeadm@server2 ~]$ echo "source <(kubectl completion bash)" >> ~/.bashrc [kubeadm@server2 ~]$ logout [root@server2 demo]# su - kubeadm Last login: Thu Jun 18 19:26:19 CST 2020 on pts/0 [kubeadm@server2 ~]$ kubectl alpha apply certificate convert #You can make it up automatically.

• Delete Vertex

[kubeadm@server2 ~]$ kubectl drain server4 --delete-local-data --force --ignore-daemonsets kunode/server4 cordoned WARNING: ignoring DaemonSet-managed Pods: kube-system/kube-flannel-ds-amd64-mlcvm, kube-system/kube-proxy-f7rnh evicting pod kube-system/coredns-5fd54d7f56-22fwz bec pod/coredns-5fd54d7f56-22fwz evicted node/server4 evicted [kubeadm@server2 ~]$ kubectl get nodes NAME STATUS ROLES AGE VERSION server2 Ready master 3h56m v1.18.3 server3 Ready <none> 3h37m v1.18.3 server4 Ready,SchedulingDisabled <none> 3h36m v1.18.3 # Do not call this node again [kubeadm@server2 ~]$ kubectl get node NAME STATUS ROLES AGE VERSION server2 Ready master 3h56m v1.18.3 server3 Ready <none> 3h37m v1.18.3 server4 Ready,SchedulingDisabled <none> 3h36m v1.18.3 [kubeadm@server2 ~]$ kubectl delete node server4 # Delete Vertex node "server4" deleted [kubeadm@server2 ~]$ kubectl get node NAME STATUS ROLES AGE VERSION server2 Ready master 3h57m v1.18.3 server3 Ready <none> 3h38m v1.18.3 [kubeadm@server2 ~]$

This only applies to nodes that have joined normally. For nodes that have not joined normally, execute directly on that node:

[root@server4 ~]# kubeadm reset [reset] WARNING: Changes made to this host by 'kubeadm init' or 'kubeadm join' will be reverted. [reset] Are you sure you want to proceed? [y/N]: y [preflight] Running pre-flight checks //Clear the information about the join //If you want to join us again: [kubeadm@server2 ~]$ kubeadm token list TOKEN TTL EXPIRES USAGES DESCRIPTION EXTRA GROUPS 61xkmb.qd1alzh6winolaeg 19h `Not yet expired` 2020-06-19T17:31:47+08:00 [root@server4 ~]# kubeadm join 172.25.254.2:6443 --token 61xkmb.qd1alzh6winolaeg --discovery-token-ca-cert-hash sha256:ef9f8d0f0866660e7a01c54ecfc65abbbb11f25147ec7da75453098a9302e597 //It's OK to add it again, provided that all the configurations in the above nodes are done well. [kubeadm@server2 ~]$ kubectl get node NAME STATUS ROLES AGE VERSION server2 Ready master 4h3m v1.18.3 server3 Ready <none> 3h43m v1.18.3 server4 Ready <none> 2m1s v1.18.3

• Delete the flannel network component

[root@server4 ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 56862b391eda 4e9f801d2217 "/opt/bin/flanneld -..." 33 minutes ago Up 33 minutes k8s_kube-flannel_kube-flannel-ds-amd64-sklll_kube-system_84e2eb08-2b85-4cc2-a167-5ea78629af3c_1 [root@server4 ~]# docker rm -f 56862b391eda 56862b391eda [root@server4 ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES f7db2b985cc5 4e9f801d2217 "/opt/bin/flanneld -..." //The cluster will monitor the status when things happen. When a service is shut down, it will automatically restart the service all the time.

• Create a pod

[kubeadm@server2 ~]$ kubectl run demo --image=nginx kubecpod/demo created [kubeadm@server2 ~]$ kubectl get pod NAME READY STATUS RESTARTS AGE demo 0/1 ContainerCreating 0 5s [kubeadm@server2 ~]$ kubectl logs demo Error from server (BadRequest): container "demo" in pod "demo" is waiting to start: ContainerCreating [kubeadm@server2 ~]$ kubectl describe pod demo #View pod details Name: demo Namespace: default Priority: 0 Node: server3/172.25.254.3 IP: 10.244.1.3 IPs: IP: 10.244.1.3 Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled <unknown> default-scheduler Successfully assigned default/demo to server3 Normal Pulling 47s kubelet, server3 Pulling image "nginx" Normal Pulled 19s kubelet, server3 Successfully pulled image "nginx" Normal Created 19s kubelet, server3 Created container demo Normal Started 18s kubelet, server3 Started container demo [kubeadm@server2 ~]$ kubectl logs demo #View pod log /docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration /docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/ /docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh 10-listen-on-ipv6-by-default.sh: Getting the checksum of /etc/nginx/conf.d/default.conf 10-listen-on-ipv6-by-default.sh: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf /docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh /docker-entrypoint.sh: Configuration complete; ready for start up [kubeadm@server2 ~]$ kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES demo 1/1 Running 0 8m58s 10.244.1.3 server3 <none> <none> # It's already running [kubeadm@server2 ~]$ curl 10.244.1.4 <!DOCTYPE html> <html> <head> <title>Welcome to nginx!</title> [kubeadm@server2 ~]$ kubectl delete pod demo pod "demo" deleted

Then we go to server3 and server4 to configure the warehouse:

[root@server3 ~]# vim /etc/docker/daemon.json [root@server4 ~]# vim /etc/docker/daemon.json { "registry-mirrors": ["https://reg.caoaoyuan.org"], # Add this line in. "exec-opts": ["native.cgroupdriver=systemd"], "log-driver": "json-file", [root@server3 ~]# systemctl restart docker

At this time, the pull image will be pulled from our harbor warehouse. The configuration of our cluster is basically ok.

18 June 2020, 22:33 | Views: 1239