运维实战 kubernetes(k8s) 的简介和部署
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1. Kubernetes简介
1.1 Kubernetes简介
- 在Docker 作为高级容器引擎快速发展的同时，在Google内部，容器技术已经应用了很多年，Borg系统运行管理着成千上万的容器应用。
- Kubernetes项目来源于Borg，可以说是集结了Borg设计思想的精华，并且吸收了Borg系统中的经验和教训。
- Kubernetes对计算资源进行了更高层次的抽象，通过将容器进行细致的组合，将最终的应用服务交给用户。
- Kubernetes的好处：
隐藏资源管理和错误处理，用户仅需要关注应用的开发。
服务高可用、高可靠。
可将负载运行在由成千上万的机器联合而成的集群中。
1.2 kubernetes设计架构
- Kubernetes集群包含有节点代理kubelet和Master组件(APIs, scheduler, etc)，一切都基于分布式的存储系统。
-
Kubernetes主要由以下几个核心组件组成：
etcd：保存了整个集群的状态
apiserver：提供了资源操作的唯一入口，并提供认证、授权、访问控制、API注册和发现等机制
controller manager：负责维护集群的状态，比如故障检测、自动扩展、滚动更新等
scheduler：负责资源的调度，按照预定的调度策略将Pod调度到相应的机器上
kubelet：负责维护容器的生命周期，同时也负责Volume（CVI）和网络（CNI）的管理
Container runtime：负责镜像管理以及Pod和容器的真正运行（CRI）
kube-proxy：负责为Service提供cluster内部的服务发现和负载均衡 -
除了核心组件，还有一些推荐的 Add-ons：
kube-dns：负责为整个集群提供DNS服务
Ingress Controller：为服务提供外网入口
Heapster：提供资源监控
Dashboard：提供GUI
Federation：提供跨可用区的集群
Fluentd-elasticsearch：提供集群日志采集、存储与查询 -
Kubernetes设计理念和功能其实就是一个类似Linux的分层架构.
核心层：Kubernetes最核心的功能，对外提供API构建高层的应用，对内提供插件式应用执行环境
应用层：部署（无状态应用、有状态应用、批处理任务、集群应用等）和路由（服务发现、DNS解析等）
管理层：系统度量（如基础设施、容器和网络的度量），自动化（如自动扩展、动态Provision等）以及策略管理（RBAC、Quota、PSP、NetworkPolicy等）
接口层：kubectl命令行工具、客户端SDK以及集群联邦
生态系统：在接口层之上的庞大容器集群管理调度的生态系统，可以划分为两个范畴
Kubernetes外部：日志、监控、配置管理、CI、CD、Workflow、FaaS、OTS应用、ChatOps等
Kubernetes内部：CRI、CNI、CVI、镜像仓库、Cloud Provider、集群自身的配置和管理等
2. Kubernetes 部署
由于k8s 和swarm 和 machine 会有冲突，先将之前的删除，再来部署；
清除 swarm 的残留信息：
[root@server2 ~]# docker stack ls
NAME SERVICES ORCHESTRATOR
myservice 2 Swarm
portainer 2 Swarm
[root@server2 ~]# docker stack rm myservice
Removing service myservice_mysrc
Removing service myservice_visualizer
Removing network myservice_default
[root@server2 ~]# docker stack rm portainer
Removing service portainer_agent
Removing service portainer_portainer
Removing network portainer_agent_network
[root@server2 ~]# docker stack ls
NAME SERVICES ORCHESTRATOR
[root@server3 ~]# docker swarm leave
Node left the swarm.
[root@server4 ~]# docker swarm leave
Node left the swarm.
[root@server2 ~]# docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
wb3shkbmvjeli9nbtwip4axdk * server2 Ready Active Leader 19.03.15
o3q60i5krbsj0701b3q8ktznd server3 Down Active 19.03.15
8cm0atk8fzr64qiywznijzpdi server4 Down Active 19.03.15
[root@server2 ~]# docker swarm leave --force ##最后一个节点，离开时必须加 --force
Node left the swarm.
[root@server2 ~]# docker container prune
[root@server2 ~]# docker network prune
[root@server2 ~]# docker volume prune
然后在其他节点依次清除
清除 macine 的残留信息：
[root@server1 ~]# docker-machine ls
NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS
server2 - generic Running tcp://172.25.25.2:2376 v19.03.15
server3 - generic Running tcp://172.25.25.3:2376 v19.03.15
server4 - generic Running tcp://172.25.25.4:2376 v19.03.15
[root@server1 ~]# docker-machine rm server2
在管理节点上依次删除，只能删除管理信息，并不能删除受控机中的信息；
依次删除受控节点上的信息，负责在部署 k8s 时可能有冲突；
[root@server2 ~]# cd /etc/systemd/system/docker.service.d/
[root@server2 docker.service.d]# ls
10-machine.conf
[root@server2 docker.service.d]# rm -f 10-machine.conf
[root@server2 docker.service.d]# ls
[root@server2 docker.service.d]# systemctl daemon-reload
然后关闭节点的 selinux 和 iptables 防火墙；
所有节点部署docker引擎
# yum install -y docker-ce docker-ce-cli
# vim /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
# sysctl --system
# systemctl enable docker
# systemctl start docker
开始部署 k8s，指定私有仓库地址和 k8s 的配置信息；
[root@server2 docker]# pwd
/etc/docker
[root@server2 docker]# cat daemon.json
{
"registry-mirrors": ["https://reg.westos.org"],
"exec-opts": ["native.cgroupdriver=systemd"],
"log-driver": "json-file",
"log-opts": {
"max-size": "100m"
},
"storage-driver": "overlay2"
}
[root@server2 docker]# systemctl restart docker
[root@server2 docker]# docker info
Server Version: 19.03.15
Storage Driver: overlay2
Backing Filesystem: xfs
Supports d_type: true
Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: systemd
Plugins:
将修改后的文件依次发至每一个节点上：
[root@server2 docker]# scp daemon.json server4:/etc/docker/
[root@server2 docker]# scp daemon.json server3:/etc/docker/
[root@server4 ~]# systemctl restart docker
禁用 swap 分区，依次禁用每个节点；
[root@server2 docker]# swapoff -a
[root@server2 docker]# vim /etc/fstab
[root@server2 docker]# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sun Apr 11 20:56:54 2021
#
# 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=e65480d0-3350-4123-9d98-ccda956cce99 /boot xfs defaults 0 0
#/dev/mapper/rhel-swap swap swap defaults 0 0
[root@server2 docker]# swapon -s
安装部署软件 kubeadm，配置 yum 源；写入的路径是指向阿里云的，此处需要联网；然后列出 kubeadm 信息，可以看到当前最新版是 1.21.1；
[root@server2 yum.repos.d]# pwd
/etc/yum.repos.d
[root@server2 yum.repos.d]# vim k8s.repo
[root@server2 yum.repos.d]# cat 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 list kubeadm
Loaded plugins: product-id, search-disabled-repos, subscription-manager
This system is not registered with an entitlement server. You can use subscription-manager to register.
docker | 3.0 kB 00:00
dvd | 4.3 kB 00:00
kubernetes | 1.4 kB 00:00
kubernetes/primary | 90 kB 00:00
kubernetes 666/666
Available Packages
kubeadm.x86_64 1.21.1-0 kubernetes
安装需要的组建：其中 kubectl 为客户端，可以只在操作集群的节点安装；
在每个节点都安装同样的软件，并且为 docker 和 kubelet 设置开机自启；
[root@server2 yum.repos.d]# yum install -y kubelet kubeadm kubectl
[root@server2 yum.repos.d]# systemctl enable --now kubelet
Created symlink from /etc/systemd/system/multi-user.target.wants/kubelet.service to /usr/lib/systemd/system/kubelet.service.
[root@server2 yum.repos.d]# systemctl enable --now docker
用命令 kubeadm config print init-defaults 查看默认配置信息；
此时查看到的信息是 1.21.0；
[root@server2 yum.repos.d]# kubeadm config print init-defaults
dns:
type: CoreDNS
etcd:
local:
dataDir: /var/lib/etcd
imageRepository: k8s.gcr.io
kind: ClusterConfiguration
kubernetesVersion: 1.21.0
networking:
dnsDomain: cluster.local
serviceSubnet: 10.96.0.0/12
scheduler: {}
默认从 k8s.gcr.io 上下载组件镜像，需要翻墙才可以，所以需要修改镜像仓库：
列出当前镜像信息；此时从阿里云下载的是 1.21.1 有点差别；
## 列出所需镜像
[root@server2 yum.repos.d]# kubeadm config images list --image-repository registry.aliyuncs.com/google_containers
registry.aliyuncs.com/google_containers/kube-apiserver:v1.21.1
registry.aliyuncs.com/google_containers/kube-controller-manager:v1.21.1
registry.aliyuncs.com/google_containers/kube-scheduler:v1.21.1
registry.aliyuncs.com/google_containers/kube-proxy:v1.21.1
registry.aliyuncs.com/google_containers/pause:3.4.1
registry.aliyuncs.com/google_containers/etcd:3.4.13-0
registry.aliyuncs.com/google_containers/coredns/coredns:v1.8.0
[root@server2 ~]# kubeadm config images list --image-repository registry.aliyuncs.com/google_containers --kubernetes-version v1.21.0
##指定版本来显示信息
registry.aliyuncs.com/google_containers/kube-apiserver:v1.21.0
registry.aliyuncs.com/google_containers/kube-controller-manager:v1.21.0
registry.aliyuncs.com/google_containers/kube-scheduler:v1.21.0
registry.aliyuncs.com/google_containers/kube-proxy:v1.21.0
registry.aliyuncs.com/google_containers/pause:3.4.1
registry.aliyuncs.com/google_containers/etcd:3.4.13-0
registry.aliyuncs.com/google_containers/coredns/coredns:v1.8.0
将这些镜像存入私有仓库，由于其他节点都指向了本地私有仓库，上传至仓库之后，此时部署起来就快很多；
此处部署 1.21.0 版本；先向私有仓库上传镜像，然后在节点拉取，拉取时需要指定版本；
在私有仓库中新建一个项目：
[root@server1 ~]# docker load -i k8s-v1.21.tar
[root@server1 ~]# docker images | grep k8s
reg.westos.org/k8s/kube-apiserver v1.21.0 4d217480042e 8 weeks ago 126MB
reg.westos.org/k8s/kube-proxy v1.21.0 38ddd85fe90e 8 weeks ago 122MB
reg.westos.org/k8s/kube-scheduler v1.21.0 62ad3129eca8 8 weeks ago 50.6MB
reg.westos.org/k8s/kube-controller-manager v1.21.0 09708983cc37 8 weeks ago 120MB
reg.westos.org/k8s/pause 3.4.1 0f8457a4c2ec 4 months ago 683kB
reg.westos.org/k8s/coredns/coredns v1.8.0 296a6d5035e2 7 months ago 42.5MB
reg.westos.org/k8s/etcd 3.4.13-0 0369cf4303ff 9 months ago 253MB
[root@server1 ~]# docker images | grep k8s | awk '{system("docker push "$1":"$2"")}'
##上传镜像
拉取镜像：
[root@server2 ~]# kubeadm config images list --image-repository reg.westos.org/k8s --kubernetes-version v1.21.0
reg.westos.org/k8s/kube-apiserver:v1.21.0
reg.westos.org/k8s/kube-controller-manager:v1.21.0
reg.westos.org/k8s/kube-scheduler:v1.21.0
reg.westos.org/k8s/kube-proxy:v1.21.0
reg.westos.org/k8s/pause:3.4.1
reg.westos.org/k8s/etcd:3.4.13-0
reg.westos.org/k8s/coredns/coredns:v1.8.0
[root@server2 ~]# kubeadm config images pull --image-repository reg.westos.org/k8s --kubernetes-version v1.21.0
##从私有仓库拉取镜像
初始化集群，此处内存必须大于 1700M；
[root@server2 ~]# kubeadm init --pod-network-cidr=10.244.0.0/16 --image-repository reg.westos.org/k8s --kubernetes-version v1.21.0
## 初始化集群
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 172.25.25.2:6443 --token pjiefh.56atgmyfn7ygd92k \\
--discovery-token-ca-cert-hash sha256:491822179cf005dd0e35e0f9761d0c3e066dc2d18fe75e092941481c055bd428
[root@server2 ~]# export KUBECONFIG=/etc/kubernetes/admin.conf
##此处为超级用户执行此命令
[root@server2 ~]# kubectl get node
NAME STATUS ROLES AGE VERSION
server2 NotReady control-plane,master 2m18s v1.21.1
[root@server2 ~]# kubectl -n kube-system get pod
##其中没有运行起来的是因为网络还没有配置完成，缺少网络组件
NAME READY STATUS RESTARTS AGE
coredns-85ffb569d4-85kp7 0/1 Pending 0 2m57s
coredns-85ffb569d4-bd579 0/1 Pending 0 2m57s
etcd-server2 1/1 Running 0 3m4s
kube-apiserver-server2 1/1 Running 0 3m4s
kube-controller-manager-server2 1/1 Running 0 3m4s
kube-proxy-qngmk 1/1 Running 0 2m57s
kube-scheduler-server2 1/1 Running 0 3m4s
安装flannel网络组件： https://github.com/coreos/flannel 官网；
此处将其下载下来在操作，方便知道做了那些事；
[root@server2 ~]# wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
[root@server2 ~]# ls
compose kube-flannel.yml portainer-agent-stack.yml
[root@server2 ~]# vim kube-flannel.yml
initContainers:
- name: install-cni
image: quay.io/coreos/flannel:v0.14.0
command:
- cp
args:
##此处有个指定的镜像
在私有仓库上也上传此镜像；
[root@server1 ~]# docker pull quay.io/coreos/flannel:v0.14.0
[root@server1 ~]# docker tag quay.io/coreos/flannel:v0.14.0 reg.westos.org/library/flannel:v0.14.0
[root@server1 ~]# docker push reg.westos.org/library/flannel:v0.14.0
完成之后，修改文件的镜像路径：
[root@server2 ~]# vim kube-flannel.yml
169 image: flannel:v0.14.0 ##私有仓库路径
170 command:
171 - cp
172 args:
173 - -f
174 - /etc/kube-flannel/cni-conf.json
175 - /etc/cni/net.d/10-flannel.conflist
176 volumeMounts:
177 - name: cni
178 mountPath: /etc/cni/net.d
179 - name: flannel-cfg
180 mountPath: /etc/kube-flannel/
181 containers:
182 - name: kube-flannel
183 image: flannel:v0.14.0 ##私有仓库路径
配置kubectl命令补齐功能：
[root@server2 ~]# echo "source <(kubectl completion bash)" >> ~/.bashrc
[root@server2 ~]# source ~/.bashrc
[root@server2 ~]# kubectl apply -f kube-flannel.yml
Warning: policy/v1beta1 PodSecurityPolicy is deprecated in v1.21+, unavailable in v1.25+
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 created
[root@server2 ~]# kubectl get pod -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-85ffb569d4-85kp7 1/1 Running 0 21m
coredns-85ffb569d4-bd579 1/1 Running 0 21m
etcd-server2 1/1 Running 0 21m
kube-apiserver-server2 1/1 Running 0 21m
kube-controller-manager-server2 1/1 Running 0 21m
kube-flannel-ds-mppbp 1/1 Running 0 38s
kube-proxy-qngmk 1/1 Running 0 21m
kube-scheduler-server2 1/1 Running 0 21m
让其他节点介入集群：
[root@server3 ~]# kubeadm join 172.25.25.2:6443 --token pjiefh.56atgmyfn7ygd92k --discovery-token-ca-cert-hash sha256:491822179cf005dd0e35e0f9761d0c3e066dc2d18fe75e092941481c055bd428
[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...
This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.
Run 'kubectl get nodes' on the control-plane to see this node join the cluster.
[root@server2 ~]# kubectl get node
NAME STATUS ROLES AGE VERSION
server2 Ready control-plane,master 25m v1.21.1
server3 Ready <none> 47s v1.21.1
server4 NotReady <none> 27s v1.以上是关于运维实战 kubernetes(k8s) 的简介和部署的主要内容，如果未能解决你的问题，请参考以下文章
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