kubernetes（2）部署k8s

kubernetes（2）部署k8s

部署kubernetes cluster

需要那些组件

我们将部署三个节点的kubernetes cluster

node	name
node1	k8smaster
node2	k8snode1
node3	k8snode2

kubernetes几乎所有的安装组件和docker镜像都放在google自己的网站，国内的话可以使用阿里云

导出各版本镜像列表
[root@server1 ~]# kubeadm config images list
W1105 10:37:37.438736    5334 version.go:101] could not 
fetch a Kubernetes version from the internet: unable
to get URL "https://dl.k8s.io/release/stable-1.txt": 
Get https://dl.k8s.io/release/stable-1.txt: net/http:
request canceled while waiting for connection 
(Client.Timeout exceeded while awaiting headers)
W1105 10:37:37.438797    5334 version.go:102] 
falling back to the local client version: v1.16.2

"""
API Server提供HTTP/HTTPS RESTful API,即Kubernetes API。
API Server是Kubernetes Cluster的前端接口,各种客户端工具
(CLI或UI)以及Kubernetes其他组件可以通过它管理Cluster的各种资源
"""
k8s.gcr.io/kube-apiserver:v1.16.2 

"""
Controller Manager负责管理Cluster各种资源,保证资源处于预期的状态
"""
k8s.gcr.io/kube-controller-manager:v1.16.2

""
Scheduler负责决定将Pod放在哪个Node上运行。Scheduler在调度
时会充分考虑Cluster的拓扑结构,当前各个节点的负载,以及应用对
高可用、性能、数据亲和性的需求"
"""
k8s.gcr.io/kube-scheduler:v1.16.2

"""
service在逻辑上代表了后端的多个Pod,外界通过service访问
Pod。service接收到的请求是如何转发到Pod的呢?这就是kube-proxy
要完成的工作
"""
k8s.gcr.io/kube-proxy:v1.16.2
k8s.gcr.io/pause:3.1

"""
etcd负责保存Kubernetes Cluster的配置信息和各种资源的状态信
息。当数据发生变化时,etcd会快速地通知Kubernetes相关组件
"""
k8s.gcr.io/etcd:3.3.15-0
k8s.gcr.io/coredns:1.6.2

下载镜像的脚本

kubeadm config images list #查看所需要的版本

#下载镜像的脚本
#!/bin/bash
# pull image form aliyun registry and docker tag k8s
# ##################################################
image_name=(
	kube-proxy:v1.15.3
	kube-apiserver:v1.15.3
	kube-controller-manager:v1.15.3
	kube-scheduler:v1.15.3
	pause:3.1
	etcd:3.3.10
	coredns:1.3.1
)
aliyun_registry="registry.cn-hangzhou.aliyuncs.com/google_containers/"

k8s_registry="k8s.gcr.io/"
 
for image in ${image_name[@]};do
docker pull $aliyun_registry$image
docker tag $aliyun_registry$image $k8s_registry$image
done


#下载完成后删除不必要的标签 
[root@server1 ~]# docker rmi registry.cn-hangzhou.aliyuncs.com/google_containers/coredns:1.6.2
[root@server3 ~]# docker images
REPOSITORY                           TAG                 IMAGE ID            CREATED             SIZE
k8s.gcr.io/kube-proxy                v1.15.3             232b5c793146        4 days ago          82.4MB
k8s.gcr.io/kube-apiserver            v1.15.3             5eb2d3fc7a44        4 days ago          207MB
k8s.gcr.io/kube-scheduler            v1.15.3             703f9c69a5d5        4 days ago          81.1MB
k8s.gcr.io/kube-controller-manager   v1.15.3             e77c31de5547        4 days ago          159MB
k8s.gcr.io/coredns                   1.3.1               eb516548c180        7 months ago        40.3MB
k8s.gcr.io/etcd                      3.3.10              2c4adeb21b4f        8 months ago        258MB
k8s.gcr.io/pause                     3.1                 da86e6ba6ca1        20 months ago       742kB

安装配置

1.安装docker并启动(三台虚拟机都做)
2.配置阿里云网络yum源头
kubelet是Node的agent,当Scheduler确定在某个Node上运行Pod
后,会将Pod的具体配置信息(image、volume等)发送给该节点的
kubelet,kubelet根据这些信息创建和运行容器,并向Master报告运行
状态

	'kubelet：运行在cluster所有节点上，负责启动pod和容器
	kubeadm：用于初始化cluster
	kubectl：是kubernetes命令行工具，通过kubectk可以部署和管理应用，查看各种资源，创建，删除和更新各种组件
	配置阿里云网络yum源头(三台虚拟机都做)'
	
[root@server1 ~]# cat /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

3.安装
yum install kubelet kubeadm kubectl -y
systemctl start docker
systemctl enable docker



4.配置免秘和关闭swap分区
master:
ssh-keygen 
ssh-copy-id server2
ssh server2
ssh-copy-id server3
ssh server3


#三个节点都要做
vim /etc/fstab 
swapoff -a

5.用kubeadm创建cluster
在master上执行：
"""
注意两个error：
1.[ERROR Swap]: running with swap on is not supported. Please disable swap

vim /etc/fstab
# Created by anaconda on Sat May 18 17:02:46 2019
#
# 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=c24172a6-4f86-450f-91f7-8542c07f7254 /boot                   xfs     defaults        0 0
#/dev/mapper/rhel-swap   swap                    swap    defaults        0 0

2.[ERROR FileContent--proc-sys-net-bridge-bridge-nf-call-iptables]: 
/proc/sys/net/bridge/bridge-nf-call-iptables contents are not set to 1

echo "1" >/proc/sys/net/bridge/bridge-nf-call-iptables
"""

[root@server1 ~]# kubeadm init --apiserver-advertise-address 172.25.0.1 --pod-network-cidr=10.244.0.0/16
# --apiserver-advertise-address:指明用master的哪个intserface与cluster的其他节点通信，
#(如果master有多个intserface,建议明确指定，如果不指定，kubeadm会自动选择有默认网关的interface)

# --pod-network-cidr= 指定pos网络的范围(lubernetes支持多种网络方案，
#而且不同的网络方案对--pod-network-cidr 有自己的要求，这里设定为 
#10.244.0.0/16 是因为我们将使用flannel网络方案，必须设置成这个CIDR)

"""
[init] Using Kubernetes version: v1.15.3
[preflight] Running pre-flight checks
	[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/
[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'
[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] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [server1 localhost] and IPs [172.25.0.1 127.0.0.1 ::1]
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [server1 localhost] and IPs [172.25.0.1 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [server1 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 172.25.0.1]
[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 "sa" key and public key
[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
[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
[apiclient] All control plane components are healthy after 20.504069 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.15" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node server1 as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node server1 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: jnclxq.kv2t3s3twn6m0e0f
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[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
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

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

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 172.25.0.1:6443 --token jnclxq.kv2t3s3twn6m0e0f \
    --discovery-token-ca-cert-hash sha256:c93d17daed5b3d5b51ee81ea239c557923a496236647a104dcb8b6709904911b 

1.kubeadm 执行初始化前的检查
2.生成token和证书
3.生成kubeconfig文件，kubelet需要用这个文件与master通信
5.安装附加组建kube-proxy 和kube-dns
6.kubernetes master初始化成功
7.提示如何配置kubectl
8.提示如何安装pod网络
9.提示如何注册其他节点到cluster
"""

6.配置kubectl
kubectl是管理kubernetes cluster的命令行工具，前面我们已经在
所有节点安装了kubectl mastart初始化完成后需要做一些配置工作，
然后kubectl就能使用了

# 根据提示执行命令 推荐linux的普通用户执行(因为root执行会有一些问题)
useradd k8s
passwd k8s
[root@server1 ~]# vim /etc/sudoers
k8s ALL=(ALL)       NOPASSWD: ALL #93行左右

su - k8s
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
# 为了便捷使用 启用kubectl命令的自动补全功能
echo "source <(kubectl completion bash)" >>~/.bashrc

7.安装pod网络
"""
Pod要能够相互通信,Kubernetes
Cluster必须部署Pod网络
"""
要让kubernetes cluster能够工作，必须安装pod网络，否则pod之间无法通信

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

8.添加node节点
[root@server2 ~]# kubeadm join --token jnclxq.kv2t3s3twn6m0e0f 172.25.0.1:6443 --discovery-token-ca-cert-hash sha256:c93d17daed5b3d5b51ee81ea239c557923a496236647a104dcb8b6709904911b

[root@server3 ~]# kubeadm join --token jnclxq.kv2t3s3twn6m0e0f 172.25.0.1:6443 --discovery-token-ca-cert-hash sha256:c93d17daed5b3d5b51ee81ea239c557923a496236647a104dcb8b6709904911b

# 后面的认证信息在master初始化的时候可以获得
# Pending、ContainerCreating、ImagePullBackOff都表明Pod没有就绪,
#Running才是就绪状态。我们可以通过kubectl describe pod 查看Pod的具体情况

# 可以看到在下载image时失败,如果网络质量不好,这种情况是很常见的。
#我们可以耐心等待,因为Kubernetes会重试 我们也可以自己手动执行docker pull去下载这个镜像

[k8s@server1 ~]$ kubectl get nodes
NAME      STATUS   ROLES    AGE     VERSION
server1   Ready    master   38m     v1.15.3
server2   Ready    <none>   8m20s   v1.15.3
server3   Ready    <none>   7m37s   v1.15.3

[k8s@server1 ~]$ kubectl get pod --all-namespaces
NAMESPACE     NAME                              READY   STATUS    RESTARTS   AGE
kube-system   coredns-5644d7b6d9-fk59p          1/1     Running   0          50m
kube-system   coredns-5644d7b6d9-tj9bp          1/1     Running   0          50m
kube-system   etcd-server1                      1/1     Running   0          49m
kube-system   kube-apiserver-server1            1/1     Running   0          49m
kube-system   kube-controller-manager-server1   1/1     Running   0          49m
kube-system   kube-flannel-ds-amd64-tm9zz       1/1     Running   0          46m
kube-system   kube-flannel-ds-amd64-ttnwn       1/1     Running   0          41m
kube-system   kube-flannel-ds-amd64-z2v9l       1/1     Running   0          42m
kube-system   kube-proxy-52qns                  1/1     Running   0          41m
kube-system   kube-proxy-8dx6g                  1/1     Running   0          50m
kube-system   kube-proxy-rmnq5                  1/1     Running   0          42m
kube-system   kube-scheduler-server1            1/1     Running   0          49m
[k8s@server1 ~]$ kubectl get nodes
NAME      STATUS   ROLES    AGE   VERSION
server1   Ready    master   50m   v1.16.2
server2   Ready    <none>   41m   v1.16.2
server3   Ready    <none>   42m   v1.16.2

[k8s@server1 ~]$ kubectl get namespaces
NAME              STATUS   AGE
default           Active   10d
kube-node-lease   Active   10d
kube-public       Active   10d
kube-system       Active   10d
# default:创建资源时如果不指定,将被放到这个Namespace中

为了帮助大家更好地理解Kubernetes架构,我们部署一个应用来演示各个组件之间是如何协作的
[k8s@server1 ~]$ kubectl run http-app --image=httpd --replicas=2
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
deployment.apps/http-app created
[k8s@server1 ~]$ kubectl get deployment
NAME       READY   UP-TO-DATE   AVAILABLE   AGE
http-app   0/2     2            0           21s
[k8s@server1 ~]$ kubectl get deployment
NAME       READY   UP-TO-DATE   AVAILABLE   AGE
http-app   1/2     2            1           26s
[k8s@server1 ~]$ kubectl get deployment
NAME       READY   UP-TO-DATE   AVAILABLE   AGE
http-app   2/2     2            2           3m48s

详细讨论整个部署过程
kubectl发送部署请求到API Server
API Server通知Controller Manager创建一个deployment资源
Scheduler执行调度任务,将两个副本Pod分发到k8s-node1和k8s-node2
k8s-node1和k8s-node2上的kubectl在各自的节点上创建并运行Pod
补充两点:
(1)应用的配置和当前状态信息保存在etcd中,执行kubectl getpod时API Server会从etcd中读取这些数据
(2)flannel会为每个Pod都分配IP。因为没有创建service,所以目前kube-proxy还没参与进来