使用kubeadm安装kubernetes及kubernetes的简单使用
1、安装前环境准备工作（1）环境准备IP地址主机名系统版本Docker版本K8s版本192.168.16.160master01.dayi123.comCent0s7.5ce版18.09.0...
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1、安装前环境准备工作
（1）环境准备
| IP地址 | 主机名 | 系统版本 | Docker版本 | K8s版本 |
| 192.168.16.160 | master01.dayi123.com | Cent0s7.5 | ce版18.09.0 | 1.13.1 |
| 192.168.16.171 | node01.dayi123.com | Cent0s7.5 | ce版18.09.0 | 1.13.1 |
| 192.168.16.172 | node02.dayi123.com | Cent0s7.5 | ce版18.09.0 | 1.13.1 |
（2）系统环境准备
1）配置主机host文件
# 在三台主机的/etc/hosts文件中分别添加主机名解析配置
192.168.16.160 master01 master01.dayi123.com
192.168.16.171 node01 node01.dayi123.com
192.168.16.172 node02 node02.dayi123.com2）关闭selinux及iptables
# 分别关闭三台主机的selinux及iptables
]# systemctl stop firewalld
]# systemctl disable firewalld
]# setenforce 0
]# sed -i "s#SELINUX=enforcing#SELINUX=disable#g" /etc/selinux/config3）配置docker及kubernetes仓库地址
# 在三台主机上分别配置docker仓库地址
~]# cd /etc/yum.repos.d/
~]# wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
# 在三台主机上分别配置kubernetes仓库地址
~]# cat /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=kubrnetes repo
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
gpgcheck=0
enabled=12、kubernetes master节点的安装
通过kubeadm安装kubernetes在master节点上只需安装docker-ce、kubeadm及kubernetes组件中的kublet、kubctl组件，其他的组件都被构建成了容器，在使用kubeadm初始化时会加载相应的容器并运行。
（1）安装并启动相应组件
# 安装相关组件
~]# yum install docker-ce kublet kubeadm kubctl
# 启动docker
~]# systemctl daemon-reload
~]# systemctl stop docker
~]# systemctl start docker
~]# systemctl enable kubelet
# 打开iptables转发规则
~]# echo 1 >/proc/sys/net/bridge/bridge-nf-call-iptables
~]# echo 1 >/proc/sys/net/bridge/bridge-nf-call-ip6tables（2）使用kubeadm初始化master节点
在使用kubeadm初始化时相应的参数可以通过” kubeadm init --help”命令查看，主要有以下的选项：
--kubernetes-version：设置kubernetes版本
--pod-network-cidr：设置pod网络
--service-cidr：设置service网络
--ignore-preflight-errors=Swap：禁用swap
# 关闭swap
]# cat /etc/sysconfig/kubelet
KUBELET_EXTRA_ARGS="--fail-swap-on=false"
# 初始化master节点
~]# kubeadm init --kubernetes-version=v1.13.1 --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12 --ignore-preflight-errors=Swap
[init] Using Kubernetes version: v1.13.1
[preflight] Running pre-flight checks
[WARNING Swap]: running with swap on is not supported. Please disable swap
[WARNING SystemVerification]: this Docker version is not on the list of validated versions: 18.09.0. Latest validated version: 18.06
[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'
error execution phase preflight: [preflight] Some fatal errors occurred:
[ERROR ImagePull]: failed to pull image k8s.gcr.io/kube-apiserver:v1.13.1: output: Error response from daemon: Get https://k8s.gcr.io/v2/: proxyconnect tcp: dial tcp: lookup www.ik83.io on 114.114.114.114:53: no such host
, error: exit status 1
……
242 packets transmitted, 0 received, 100% packet loss, time 241080ms在初始化的过程中，需要从https://k8s.gcr.io/v2/站点下载相关的docker镜像，由于https://k8s.gcr.io/v2/这个站点国内无法访问，所以初始化时会报上面的错误；但是，dockerhub仓库对google这个站点做了镜像，所以，我们可以从dockerhub的镜像站点中去拉去镜像，拉取完成后重新打标签。也可以在初始化的时候通过指定仓库地址自动拉取镜像完成初始化，比如指定阿里的仓库地址"--image-repository registry.aliyuncs.com/google_containers".
# 在docker hub拉去相应的镜像并重新打标
~]# docker pull mirrorgooglecontainers/kube-apiserver:v1.13.1
~]# docker tag mirrorgooglecontainers/kube-apiserver:v1.13.1 k8s.gcr.io/kube-apiserver:v1.13.1
~]# docker pull mirrorgooglecontainers/kube-controller-manager:v1.13.1
~]# docker tag mirrorgooglecontainers/kube-controller-manager:v1.13.1 k8s.gcr.io/kube-controller-manager:v1.13.1
~]# docker pull mirrorgooglecontainers/kube-scheduler:v1.13.1
~]# docker tag mirrorgooglecontainers/kube-scheduler:v1.13.1 k8s.gcr.io/kube-scheduler:v1.13.1
~]# docker pull mirrorgooglecontainers/kube-proxy:v1.13.1
~]# docker tag mirrorgooglecontainers/kube-proxy:v1.13.1 k8s.gcr.io/kube-proxy:v1.13.1
~]# docker pull mirrorgooglecontainers/pause:3.1
~]# docker tag mirrorgooglecontainers/pause:3.1 k8s.gcr.io/pause:3.1
~]# docker pull mirrorgooglecontainers/etcd:3.2.24
~]# docker tag mirrorgooglecontainers/etcd:3.2.24 k8s.gcr.io/etcd:3.2.24
~]# docker pull coredns/coredns:1.2.6
~]# docker tag coredns/coredns:1.2.6 k8s.gcr.io/coredns:1.2.6镜像手动拉取完成后，重新初始化master节点。
# 重新初始化
~]# kubeadm init --kubernetes-version=v1.13.1 --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12 --ignore-preflight-errors=Swap
[init] Using Kubernetes version: v1.13.1
[preflight] Running pre-flight checks
[WARNING Swap]: running with swap on is not supported. Please disable swap
[WARNING SystemVerification]: this Docker version is not on the list of validated versions: 18.09.0. Latest validated version: 18.06
[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"
……
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/
You can now join any number of machines by running the following on each node
as root:
kubeadm join 192.168.16.160:6443 --token p1oy6h.ynakxpzoco505z1h --discovery-token-ca-cert-hash sha256:f85d1778acf19651b092f4ebba09e1ed0d7d4c853999ab54de00f878d61367ac初始化完成以后，需要根据提示使用普通用户完成以下的操作：
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config（3）安装flannel网络功能
（flannel的github地址为：https://github.com/coreos/flannel/）
# 安装flannel网络功能，下面的命令执行成功后，会去拉取flannel docker镜像，这个过程会在后台执行，这个过程有点慢。
~]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created
# flannel网络安装完成后，master节点主要包含了以下的docker镜像
~]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
k8s.gcr.io/kube-proxy v1.13.1 fdb321fd30a0 10 days ago 80.2MB
k8s.gcr.io/kube-apiserver v1.13.1 40a63db91ef8 10 days ago 181MB
k8s.gcr.io/kube-controller-manager v1.13.1 26e6f1db2a52 10 days ago 146MB
k8s.gcr.io/kube-scheduler v1.13.1 ab81d7360408 10 days ago 79.6MB
k8s.gcr.io/coredns 1.2.6 f59dcacceff4 6 weeks ago 40MB
k8s.gcr.io/etcd 3.2.24 3cab8e1b9802 3 months ago 220MB
quay.io/coreos/flannel v0.10.0-amd64 f0fad859c909 11 months ago 44.6MB
k8s.gcr.io/pause 3.1 da86e6ba6ca1 12 months ago 742kB3、kubernetes node节点的安装
（1）安装kubeadm及启动相应服务
Master节点安装及初始化完成后，node节点只需要安装docker-ce及kubeadm、kubelet，并将node节点加入到集群中即可。
# 安装kubadm及docker-ce
~]# yum install docker-ce kublet kubeadm kubctl
# 启动docker
~]# systemctl daemon-reload
~]# systemctl stop docker
~]# systemctl start docker
# 打开iptables装发规则
~]# echo 1 >/proc/sys/net/bridge/bridge-nf-call-iptables
~]# echo 1 >/proc/sys/net/bridge/bridge-nf-call-ip6tables（2）初始化node节点并将node节点加入kubernetes集群
运行命令初始化node节点并将node节点加入集群时，node节点也需要去https://k8s.gcr.io/v2/站点拉取k8s.gcr.io/kube-proxy-amd64、k8s.gcr.io/pause镜像，同时还要拉取quay.io/coreos/flannel镜像；由于https://k8s.gcr.io/v2/无法访问，所以，也需要将在https://k8s.gcr.io/v2/站点拉取的镜像在dockerhub上拉取下来并重新打标签，或者将master节点上的镜像通过”docker load”命令导出，在node节点上通过”docker import”命令导入。
# 拉去相应的镜像并重新打标
~]# docker pull mirrorgooglecontainers/pause:3.1
~]# docker tag mirrorgooglecontainers/pause:3.1 k8s.gcr.io/pause:3.1
~]# docker pull mirrorgooglecontainers/kube-proxy:v1.13.1
~]# docker tag mirrorgooglecontainers/kube-proxy:v1.13.1 k8s.gcr.io/kube-proxy:v1.13.1镜像准备好之后，就可以对node节点初始化，并将node节点加入集群中。将node节点加入集群的命令在安装master节点后会自动生成，如果忘记还可去master节点查看。
# 查看node加入集群mster上生成的token等信息（需要在master上操作）
~]# kubeadm token create --print-join-command
W0809 11:04:37.148887 6878 validation.go:28] Cannot validate kube-proxy config - no validator is available
W0809 11:04:37.148959 6878 validation.go:28] Cannot validate kubelet config - no validator is available
kubeadm join 192.168.16.160:6443 --token p1oy6h.ynakxpzoco505z1h --discovery-token-ca-cert-hash sha256:f85d1778acf19651b092f4ebba09e1ed0d7d4c853999ab54de00f878d61367ac
# 初始化node节点并将node节点加入集群，下面初始化命令为在master节点初始化完成后生成的命令
~]# kubeadm join 192.168.16.160:6443 --token p1oy6h.ynakxpzoco505z1h --discovery-token-ca-cert-hash sha256:f85d1778acf19651b092f4ebba09e1ed0d7d4c853999ab54de00f878d61367ac --ignore-preflight-errors=Swap（3）在主节点进行集群的验证
# 查看各节点的状态
~]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
master01.dayi123.com Ready master 8h v1.13.1
node01.dayi123.com Ready <none> 7h3m v1.13.1
node02.dayi123.com Ready <none> 6h41m v1.13.1
# 查看kubernetes命名空间
~]# kubectl get ns
NAME STATUS AGE
default Active 8h
kube-public Active 8h
kube-system Active 8h
# 查看集群服务状态信息
~]# kubectl get cs
NAME STATUS MESSAGE ERROR
controller-manager Healthy ok
scheduler Healthy ok
etcd-0 Healthy {"health": "true"}
# 查看集群中各服务组件的运行状态及详细信息
~]# kubectl get pods -n kube-system -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
coredns-86c58d9df4-5kh2t 1/1 Running 0 6h43m 10.244.0.3 master01.dayi123.com <none> <none>
coredns-86c58d9df4-cwwjp 1/1 Running 0 8h 10.244.0.2 master01.dayi123.com <none> <none>
etcd-master01.dayi123.com 1/1 Running 0 8h 192.168.16.160 master01.dayi123.com <none> <none>
kube-apiserver-master01.dayi123.com 1/1 Running 0 8h 192.168.16.160 master01.dayi123.com <none> <none>
kube-controller-manager-master01.dayi123.com 1/1 Running 1 8h 192.168.16.160 master01.dayi123.com <none> <none>
kube-flannel-ds-amd64-4grnp 1/1 Running 67 6h48m 192.168.16.171 node01.dayi123.com <none> <none>
kube-flannel-ds-amd64-5nz7b 1/1 Running 0 8h 192.168.16.160 master01.dayi123.com <none> <none>
kube-flannel-ds-amd64-hg2f6 1/1 Running 56 6h26m 192.168.16.172 node02.dayi123.com <none> <none>
kube-proxy-65zh5 1/1 Running 0 6h26m 192.168.16.172 node02.dayi123.com <none> <none>
kube-proxy-9cvkd 1/1 Running 0 6h48m 192.168.16.171 node01.dayi123.com <none> <none>
kube-proxy-pqpjt 1/1 Running 0 8h 192.168.16.160 master01.dayi123.com <none> <none>
kube-scheduler-master01.dayi123.com 1/1 Running 1 8h 192.168.16.160 master01.dayi123.com <none> <none>
# 查看集群状态信息
~]# kubectl cluster-info
Kubernetes master is running at https://192.168.16.160:6443
KubeDNS is running at https://192.168.16.160:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy4、kubernetes的简单实用
Kubernetes安装完成后，我们可以在master节点上通过kubectl客户端完成一些简单的操作。
（1）创建pod
Kubernetes中的最小运行单元为pod, Kubernetes集群安装完成后，就可以创建pod，在pod中运行需要运行的服务。
# 创建一个包含nginx服务的pod并运行为dry-run模式
~]# kubectl run nginx-test --image=nginx:1.14-alpine --port=80 --replicas=1 --dry-run=true 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/nginx-test created (dry run)
#创建一个包含nginx服务的pod并运行
~]# kubectl run nginx-test --image=nginx:1.14-alpine --port=80 --replicas=1
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/nginx-test created
# 可以看到nginx正在创建中
~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx-test-5bbfddf46b-bgjtz 0/1 ContainerCreating 0 33s
# 查看创建的deploy
~]# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-test 1/1 1 1 3m20s服务所在的pod创建完成并运行起来后，就可以集群内的任何一个节点上访问该服务，但在该外部是无法访问的。
# 创建完成后查看详细信息，获取nginx所在pod的内部IP地址
~]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-test-5bbfddf46b-bgjtz 1/1 Running 0 4m21s 10.244.2.2 node02.dayi123.com <none> <none>
# 在kubernetes集群内任意节点访问该nginx服务
~]# curl 10.244.2.2
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>（2）创建与管理service
当我们将pod创建完成后，我们访问该pod内的服务只能在集群内部通过pod的的地址去访问该服务；当该pod出现故障后，该pod的控制器会重新创建一个包括该服务的pod,此时访问该服务须要获取该服务所在的新的pod的地址去访问。对此，我们可以创建一个service，当新的pod的创建完成后，service会通过pod的label连接到该服务，我们只需通过service即可访问该服务。
# 删除当前的pod
~]# kubectl delete pods nginx-test-5bbfddf46b-bgjtz
pod "nginx-test-5bbfddf46b-bgjtz" deleted
# 删除pod后，查看pod信息时发现有创建了一个新的pod
~]# kubectl get pod -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-test-5bbfddf46b-w56l5 1/1 Running 0 34s 10.244.2.3 node02.dayi123.com <none> <none>service的创建是通过”kubectl expose”命令来创建。该命令的具体用法可以通过” kubectl expose --help”查看。Service创建完成后，通过service地址访问pod中的服务依然只能通过集群内部的地址去访问。
# 创建service,并将包含nginx-test的标签加入进来
~]# kubectl expose deployment nginx-test --name=nginx --port=80 --target-port=80 --protocol=TCP
service/nginx exposed
# 查看创建的service
~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 13h
nginx ClusterIP 10.110.225.133 <none> 80/TCP 2m49s
# 此时就可以直接通过service地址访问nginx，pod被删除重新创建后，依然可以通过service访问pod中的服务。
~]# curl 10.110.225.133
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>Service被创建后，我们可以通过service的名称去访问该service下的pod中的服务，但前提是，需要配置dns地址为core dns服务的地址；新建的pod中的DNS的地址为都为core DNS的地址；我们可以新建一个pod客户端完成测试。
# 查看coredns的地址
~]# kubectl get svc -n kube-system
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kube-dns ClusterIP 10.96.0.10 <none> 53/UDP,53/TCP 14h
# 新建一个pod客户端
~]# kubectl run client --image=busybox --replicas=1 -it --restart=Never
# 查看pod中容器的dns地址
/ # cat /etc/resolv.conf
nameserver 10.96.0.10
# 通过名称去访问service
/ # wget -O - -q nginx
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>不同的service选择不同的pod是通过pod标签来管理的，pod标签是在创建pod时指定的，service管理的标签也是在创建service时指定的。一个service管理的标签及pod的标签都可以通过命令查看。
# 查看名称为nginx的service管理的标签以及其他信息
~]# kubectl describe svc nginx
Name: nginx
Namespace: default
Labels: run=nginx-test
Annotations: <none>
Selector: run=nginx-test
Type: ClusterIP
IP: 10.110.225.133
Port: <unset> 80/TCP
TargetPort: 80/TCP
Endpoints: 10.244.2.3:80
Session Affinity: None
Events: <none>
# 查看pod的标签
~]# kubectl get pods --show-labels
NAME READY STATUS RESTARTS AGE LABELS
client 1/1 Running 0 21m run=client
nginx-test-5bbfddf46b-w56l5 1/1 Running 0 41m pod-template-hash=5bbfddf46b,run=nginx-testcoredns服务对service名称的解析是实时的，在service被重新创建后或者修改service的ip地址后，依然可以通过service名称访问pod中的服务。
# 删除并重新创建一个名称为nginx的service
~]# kubectl delete svc nginx
service "nginx" deleted
~]# kubectl expose deployment nginx-test --name=nginx
service/nginx exposed
# 获取新创建的service的IP地址
~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 14h
nginx ClusterIP 10.98.192.150 <none> 80/TCP 9s（3）pod的扩展与缩减
Pod创建完成后，当服务的访问量过大时，可以对pod的进行扩展让pod中的服务处理更多的请求；当访问量减小时，可以缩减pod数量，以节约资源。 这些操作都可以在线完成，并不会影响现有的服务。
# 扩展pod数量
~]# kubectl scale --replicas=5 deployment nginx-test
deployment.extensions/nginx-test scaled
# 查看扩展后的pod
~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
client 1/1 Running 0 59m
nginx-test-5bbfddf46b-6kw49 1/1 Running 0 44s
nginx-test-5bbfddf46b-k6jh7 1/1 Running 0 44s
nginx-test-5bbfddf46b-pswmp 1/1 Running 1 9m19s
nginx-test-5bbfddf46b-w56l5 1/1 Running 1 79m
nginx-test-5bbfddf46b-wwtwz 1/1 Running 0 44s
# 缩减pod的数量为2个
~]# kubectl scale --replicas=2 deployment nginx-test
deployment.extensions/nginx-test scaled（4）服务的在线升级与回滚
在kubernetes服务中部署完服务后，对服务的升级可以在线完成，升级出问题后，也可以在线完成回滚。
# 查看pod的名称及pod详细信息
~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx-test-5bbfddf46b-6kw49 1/1 Running 0 32m
……
# 查看pod详细信息
~]# kubectl describe pods nginx-test-5bbfddf46b-6kw49
Name: nginx-test-5bbfddf46b-6kw49
Namespace: default
Priority: 0
PriorityClassName: <none>
Node: node02.dayi123.com/192.168.16.172
Start Time: Tue, 25 Dec 2018 15:59:35 +0800
Labels: pod-template-hash=5bbfddf46b
run=nginx-test
Annotations: <none>
Status: Running
IP: 10.244.2.8
Controlled By: ReplicaSet/nginx-test-5bbfddf46b
Containers:
nginx-test:
Container ID: docker://5537c32a16b1dea8104b32379f1174585e287bf0e44f8a1d6c4bd036d5b1dfba
Image: nginx:1.14-alpine
……
# 为了验证更加明显，更新时将nginx替换为httpd服务
~]# kubectl set image deployment nginx-test nginx-test=httpd:2.4-alpine
deployment.extensions/nginx-test image updated
# 实时查看更新过程
~]# kubectl get deployment -w
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-test 4/5 5 4 5h36m
nginx-test 3/5 5 3 5h37m
nginx-test 4/5 5 4 5h38m
nginx-test 5/5 5 5 5h38m
nginx-test 5/5 5 5 5h38m
nginx-test 4/5 5 4 5h38m
nginx-test 5/5 5 5 5h38m
# 更新完成后在客户端验证
/ # wget -O - -q nginx
<html><body><h1>It works!</h1></body></html>
# 通过kubernetes节点验证
~]# curl 10.98.192.150
<html><body><h1>It works!</h1></body></html>
# 更新后回滚为原来的nginx
~]# kubectl rollout undo deployment nginx-test
deployment.extensions/nginx-test rolled back
# 实时查看回滚的进度
~]# kubectl get deployment -w
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-test 4/5 5 4 5h48m
nginx-test 5/5 5 5 5h48m
nginx-test 5/5 5 5 5h48m
nginx-test 4/5 5 4 5h48m
. . . . .
# 回滚完成后验证
~]# curl 10.98.192.150
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>（5）让节点外部客户能够通过service访问pod中服务
创建好pod及service后，无论是通过pod地址及service地址在集群外部都无法访问pod中的服务；如果想要在集群外部访问pod中的服务，需要修改service的类型为NodePort，修改后会自动在ipvs中添加nat规则，此时就可以通过node节点地址访问pod中的服务。
# 编辑配置文件
~]# kubectl edit svc nginx
. . . . . .
spec:
clusterIP: 10.98.192.150
ports:
- port: 80
protocol: TCP
targetPort: 80
selector:
run: nginx-test
sessionAffinity: None
type: NodePort
# 配置完成后查看node节点监听的端口
~]# netstat -lntp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 127.0.0.1:10248 0.0.0.0:* LISTEN 1703/kubelet
tcp 0 0 127.0.0.1:10249 0.0.0.0:* LISTEN 100485/kube-proxy
tcp 0 0 127.0.0.1:41101 0.0.0.0:* LISTEN 1703/kubelet
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 849/sshd
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 937/master
tcp6 0 0 :::10250 :::* LISTEN 1703/kubelet
tcp6 0 0 :::31438 :::* LISTEN 100485/kube-proxy 修改完配置后，查看node节点监听的端口发现多了31438端口，在外部可以通过node节点的地址及该端口访问pod内的服务。
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