kubernetes入门实践

2023-05-16

k8s中文文档

k8s概念比较多，有什么概念的疑惑的推荐看k8s中文文档。

me的环境

操作系统：centos7
docker：1.12.6

环境跟me的不一致？不要慌，基本大部分操作都是行的通的。

还慌？那就直接用网页在线版的kubernets吧

kubernets单机版安装部署

kubernetes部署算是有一定门槛的。为了不从入门到放弃，推荐一开始安装单机版作为入门熟悉kubectl指令、了解工作原理。

安装流程，切换成root

# 关闭centos自带的防火墙

$ sudo systemctl disable firewalld

$ sudo systemctl stop firewalld

# 安装etcd和kubernetes软件（会自动安装docker）

$ sudo yum install -y etcd kubernetes

修改两处配置

Docker配置文件/etc/sysconfig/docker, OPTIONS=’–selinux-enabled=false –insecure-registry gcr.io’

# Modify these options if you want to change the way the docker daemon runs

OPTIONS='--selinux-enabled=false --insecure-registry gcr.io'

if [ -z "${DOCKER_CERT_PATH}" ]; then

DOCKER_CERT_PATH=/etc/docker

fi

# Do not add registries in this file anymore. Use /etc/containers/registries.conf

# from the atomic-registries package.

#

# docker-latest daemon can be used by starting the docker-latest unitfile.

# To use docker-latest client, uncomment below lines

#DOCKERBINARY=/usr/bin/docker-latest

#DOCKERDBINARY=/usr/bin/dockerd-latest

#DOCKER_CONTAINERD_BINARY=/usr/bin/docker-containerd-latest

#DOCKER_CONTAINERD_SHIM_BINARY=/usr/bin/docker-containerd-shim-latest

Kubernetes apiservce配置文件/etc/kubernetes/apiserver,把–admission_control参数钟的ServiceAccount删除

###

# kubernetes system config

#

# The following values are used to configure the kube-apiserver

#

# The address on the local server to listen to.

KUBE_API_ADDRESS="--insecure-bind-address=0.0.0.0"

# The port on the local server to listen on.

# KUBE_API_PORT="--port=8080"

# Port minions listen on

# KUBELET_PORT="--kubelet-port=10250"

# Comma separated list of nodes in the etcd cluster

KUBE_ETCD_SERVERS="--etcd-servers=http://127.0.0.1:2379"

# Address range to use for services

KUBE_SERVICE_ADDRESSES="--service-cluster-ip-range=10.254.0.0/16"

# default admission control policies

KUBE_ADMISSION_CONTROL="--admission-control=NamespaceLifecycle,NamespaceExists,LimitRanger,SecurityContextDeny,ResourceQuota"

# Add your own!

KUBE_API_ARGS=""

启动所有服务

# systemctl start etcd

# systemctl start docker

# systemctl start kube-apiserver

# systemctl start kube-controller-manager

# systemctl start kube-scheduler

# systemctl start kubelet

# systemctl start kube-proxy

初入门小实例

部署nginx服务
$ kubectl run my-nginx --image=nginx --port=80

$ kubectl get pod # 查看pod

发现pod状态无论多久都是处于pending。READY字段一直是0/1,服务部署失败的原因是”中国墙“的问题导致无法下载pod启动时需要的谷歌镜像，所以我们得间接的创建所需的镜像。

补充： Pending状态表示API Server已经创建Pod，但Pod内还有一个或者多个容器没有创建，或者正在下载镜像的过程。详细的参考Pod声明周期和重启策略

创建gcr.io/google_containers/pause-amd64:3.0镜像
$ docker pull googlecontainer/pause-amd64:3.0

$ docker tag googlecontainer/pause-amd64:3.0 gcr.io/google_containers/pause-amd64:3.0

kubernets指令

实例流程

# 查看版本

$ kubectl version

Client Version: version.Info{Major:"1", Minor:"5", GitVersion:"v1.5.2", GitCommit:"269f928217957e7126dc87e6adfa82242bfe5b1e", GitTreeState:"clean", BuildDate:"2017-07-03T15:31:10Z", GoVersion:"go1.7.4", Compiler:"gc", Platform:"linux/amd64"}

Server Version: version.Info{Major:"1", Minor:"5", GitVersion:"v1.5.2", GitCommit:"269f928217957e7126dc87e6adfa82242bfe5b1e", GitTreeState:"clean", BuildDate:"2017-07-03T15:31:10Z", GoVersion:"go1.7.4", Compiler:"gc", Platform:"linux/amd64"}

# 显示集群信息

$ kubectl cluster-info

Kubernetes master is running at http://localhost:8080

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

# 查看集群中有几个Node

$ kubectl get nodes

NAME STATUS AGE

127.0.0.1 Ready 18h

# 运行一个镜像

$ kubectl run my-nginx --image=nginx --replicas=2 --port=80

deployment "my-nginx" created

# 查看pod

$ kubectl get pods

NAME READY STATUS RESTARTS AGE

my-nginx-379829228-cwlbb 0/1 ContainerCreating 0 20s

my-nginx-379829228-czk6w 1/1 Running 0 20s

# 查看服务详情信息

$ kubectl describe pod my-nginx-379829228-cwlbb

# 查看已部署

$ kubectl get deployments

NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE

my-nginx 2 2 2 2 3m

# 删除pod

$ kubectl delete pod my-nginx-379829228-cwlbb

pod "my-nginx-379829228-cwlbb" deleted

# 再次查看pod，发现由于replicas机制，pod又生成一个新的

$ kubectl get pods

NAME READY STATUS RESTARTS AGE

my-nginx-379829228-czk6w 1/1 Running 0 11m

my-nginx-379829228-gjd7d 0/1 ContainerCreating 0 5s

# 删除部署的my-nginx服务。彻底删除pod

$ kubectl delete deployment my-nginx

deployment "my-nginx" deleted

对比docker命令

k8s的学习路线基本都是从docker[容器]到k8s的，因此两个对比理解有助于记忆

# docker run

$ docker run -d -e DOMAIN=cluster --name my-nginx -p 80:80 nginx

$ kubectl run my-nginx --image=nginx --port=80 --env="DOMAIN=cluster"

# docker ps

$ docker ps

$ kubectl get pods

# docker exec

$ docker exec [容器id] ls

$ kubectl exec [pod_id] ls

# docker exec 交互式

$ docker exec -it [容器id] /bin/sh

$ kubectl exec -it [pod_id] -- /bin/sh

# docker info

$ docker info

$ kubectl cluster-info

重要名词

名词	翻译
Namespace	命名空间
Endpoint	服务端点
Controller Manager	管理控制中心
Replication	副本控制器

yaml文件管理服务

用yaml文件来创建服务
# vi nginx.yaml

piVersion: extensions/v1beta1

kind: Deployment

metadata:

name: my-nginx

spec:

replicas: 3

template:

metadata:

labels:

app: nginx

spec:

containers:

- name: nginx

image: nginx:1.7.9

ports:

- containerPort: 80
启动管理服务
# 根据yaml文件创建服务

$ kubectl create -f nginx.yaml

deployment "my-nginx" created

# 查看deployment

$ kubectl get deployments

NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE

my-nginx 3 3 3 3 6s

# 查看Pod

$ kubectl get pod

NAME READY STATUS RESTARTS AGE

my-nginx-4087004473-dtrjp 1/1 Running 0 7s

my-nginx-4087004473-jz80p 1/1 Running 0 7s

my-nginx-4087004473-wh576 1/1 Running 0 7s

# 根据yaml文件删除服务

$ kubectl delete -f nginx.yaml

deployment "my-nginx" deleted

$ kubectl get pod

No resources found.

$ kubectl get deployment

No resources found.

Service

到此，我们部署一个nginx服务
$ kubectl run my-nginx --image=nginx --port=80

# 创建一个service 且将其暴露到集群外可供访问

$ kubectl expose deployment/my-nginx --type="NodePort" --port 80

service "my-nginx" exposed

# 此时service列表多个my-nginx服务

$ kubectl get services

NAME CLUSTER-IP EXTERNAL-IP PORT(S) AGE

kubernetes 10.254.0.1 <none> 443/TCP 7d

my-nginx 10.254.255.103 <nodes> 80:32589/TCP 7s

宿主主机内访问该服务

$ kubectl describe service/my-nginx

# 显示的字段有Endpoints: 172.17.0.2:80

$ curl 172.17.0.2.80

Alt text

同网段的机器访问该服务

$ curl 192.168.33.101:32589

deployments

# 运行nginx镜像

$ kubectl run my-nginx --image=nginx --port=80

# 交互式 shell 的方式运行 pod

$ kubectl run -i --tty my-nginx --image=nginx --port=80 -- sh

# 链接到运行中的容器

$ kubectl attach my-nginx-532658988-10kxd -i

# 查看deployment

$ kubectl get deployments

NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE

my-nginx 1 1 1 1 25m

# 扩展10个副本

$ kubectl scale deployment my-nginx --replicas=10

deployment "my-nginx" scaled

$ kubectl scale deployment/my-nginx --replicas=10 # 作用效果等同上一条命令

deployment "my-nginx" scaled

# 再次显示deployment

$ kubectl get deployments

NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE

my-nginx 10 10 10 1 26m

$ kubectl get pods

NAME READY STATUS RESTARTS AGE

my-nginx-379829228-38hkg 1/1 Running 0 5m

my-nginx-379829228-7j15l 1/1 Running 0 31m

my-nginx-379829228-c8mt3 1/1 Running 0 5m

my-nginx-379829228-f6mm8 1/1 Running 0 5m

my-nginx-379829228-q1rj0 1/1 Running 0 5m

my-nginx-379829228-qg7lf 1/1 Running 0 5m

my-nginx-379829228-rjfbq 1/1 Running 0 5m

my-nginx-379829228-v581r 1/1 Running 0 5m

my-nginx-379829228-wh49w 1/1 Running 0 5m

my-nginx-379829228-wpn98 1/1 Running 0 5m

# 缩扩到1个副本

$ kubectl scale deployment/my-nginx --replicas=1

deployment "my-nginx" scaled

$ kubectl scale deployment my-nginx --replicas=1 # 作用效果等同上一条命令

deployment的更新回滚

Alt text

$ kubectl create -f nginx.yaml

$ kubectl get pod

NAME READY STATUS RESTARTS AGE

my-nginx-4087004473-4xj74 1/1 Running 0 3m

my-nginx-4087004473-jkptq 1/1 Running 0 3m

my-nginx-4087004473-m55s1 1/1 Running 0 3m

$ kubectl get deployment

NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE

my-nginx 3 3 3 3 4m

# 更新应用的镜像从1.7.9版本——>1.9.1

$ kubectl set image deployment/my-nginx nginx=nginx:1.9.1

deployment "my-nginx" image updated

# 确认是否更新成功

$ kubectl rollout status deployment/my-nginx

deployment "my-nginx" successfully rolled out

# 回滚到上一代版本

$ kubectl rollout undo deployment/my-nginx

deployment "my-nginx" rolled back

ConfigMap-容器应用的配置管理

应用部署的一个最佳实践是将应用所需配置信息和程序进行分离，一则程序可以更好的复用，二则能灵活的更改配置从而实现其他功能。

使用configMap替代环境变量

以yaml文件方式创建ConfigMap

# vi special-config.yaml

apiVersion: v1

kind: ConfigMap

metadata:

name: special-config

namespace: default

data:

special.how: very

special.type: charm

# vi env-config.yaml

apiVersion: v1

kind: ConfigMap

metadata:

name: env-config

namespace: default

data:

log_level: INFO

可以在Pod中这样使用ConfigMap

# vi configMap.yaml

apiVersion: v1

kind: Pod

metadata:

name: dapi-test-pod

spec:

containers:

- name: test-container

image: nginx

command: [ "/bin/sh", "-c", "env" ]

env:

- name: SPECIAL_LEVEL_KEY #定义环境变量名称

valueFrom: #key"special.how"对应的值

configMapKeyRef:

name: special-config #环境变量的值

key: special.how

- name: SPECIAL_TYPE_KEY

valueFrom:

configMapKeyRef:

name: special-config

key: special.type

restartPolicy: Never

启动等一系列操作

$ kubectl create -f special-config.yaml

configmap "special-config" created

$ kubectl create -f env-config.yaml

configmap "env-config" created

# 查看ConfigMap

$ kubectl get configmaps

NAME DATA AGE

env-config 1 38m

special-config 2 39m

# 让我们看一下创建的ConfigMap

$ kubectl describe configmap env-config

Name: env-config

Namespace: default

Labels: <none>

Annotations: <none>

Data

====

log_level: 4 bytes

# 查看ConfigMap键的值

$ kubectl get configmaps env-config -o yaml

apiVersion: v1

data:

log_level: INFO

kind: ConfigMap

metadata:

creationTimestamp: 2017-11-30T07:29:49Z

name: env-config

namespace: default

resourceVersion: "285268"

selfLink: /api/v1/namespaces/default/configmaps/env-config

uid: 3f473adf-d5a0-11e7-9830-0800275ae9e7

$ kubectl create -f configMap.yaml

pod "dapi-test-pod" created

# 查看pod，状态ContainerCreating

$ kubectl get pod

NAME READY STATUS RESTARTS AGE

dapi-test-pod 0/1 ContainerCreating 0 3s

# 隔一段时间再查看pod,发现并没有返回什么

$ kubectl get pod

# 显示所有的权限查看pod

$ kubectl get pod --show-all

NAME READY STATUS RESTARTS AGE

dapi-test-pod 0/1 Completed 0 1m

# 查看详情

$ kubectl describe pod dapi-test-pod

Name: dapi-test-pod

Namespace: default

Node: 127.0.0.1/127.0.0.1

Start Time: Thu, 30 Nov 2017 15:32:00 +0800

Labels: <none>

Status: Succeeded

IP:

Controllers: <none>

Containers:

test-container:

Container ID: docker://1ba533f43ee60c02e03dafb7bcb8495fc12264aaab229872df0b289a3c1b9976

Image: nginx

Image ID: docker-pullable://docker.io/nginx@sha256:b81f317384d7388708a498555c28a7cce778a8f291d90021208b3eba3fe74887

Port:

Command:

/bin/sh

-c

env

State: Terminated

Reason: Completed

Exit Code: 0

Started: Thu, 30 Nov 2017 15:32:25 +0800

Finished: Thu, 30 Nov 2017 15:32:25 +0800

Ready: False

Restart Count: 0

Volume Mounts: <none>

Environment Variables:

SPECIAL_LEVEL_KEY: <set to the key 'special.how' of config map 'special-config'>

SPECIAL_TYPE_KEY: <set to the key 'special.type' of config map 'special-config'>

Conditions:

Type Status

Initialized True

Ready False

PodScheduled True

No volumes.

QoS Class: BestEffort

Tolerations: <none>

Events:

FirstSeen LastSeen Count From SubObjectPath Type Reason Message

--------- -------- ----- ---- ------------- -------- ------ -------

3m 3m 1 {default-scheduler } Normal Scheduled Successfully assigned dapi-test-pod to 127.0.0.1

3m 3m 1 {kubelet 127.0.0.1} spec.containers{test-container} Normal Pulling pulling image "nginx"

 3m 2m 2 {kubelet 127.0.0.1} Warning MissingClusterDNS kubelet does not have ClusterDNS IP configured and cannot create Pod using "ClusterFirst" policy. Falling back to DNSDefault policy.

2m 2m 1 {kubelet 127.0.0.1} spec.containers{test-container} Normal Pulled Successfully pulled image "nginx"

 2m 2m 1 {kubelet 127.0.0.1} spec.containers{test-container} Normal Created Created container with docker id 1ba533f43ee6; Security:[seccomp=unconfined]

 2m 2m 1 {kubelet 127.0.0.1} spec.containers{test-container} Normal Started Started container with docker id 1ba533f43ee6

# 可知container started 成功，进一步查看日志

$ docker logs 1ba

KUBERNETES_SERVICE_PORT=443

KUBERNETES_PORT=tcp://10.254.0.1:443

MY_SERVICE_PORT_80_TCP=tcp://10.254.110.249:80

MY_SERVICE_PORT_443_TCP_ADDR=10.254.110.249

HOSTNAME=dapi-test-pod

MY_SERVICE_PORT_443_TCP_PORT=443

HOME=/root

MY_SERVICE_PORT_443_TCP_PROTO=tcp

MY_SERVICE_SERVICE_PORT_HTTP=80

SPECIAL_TYPE_KEY=charm

MY_SERVICE_SERVICE_PORT_HTTPS=443

MY_SERVICE_PORT_443_TCP=tcp://10.254.110.249:443

MY_SERVICE_SERVICE_HOST=10.254.110.249

KUBERNETES_PORT_443_TCP_ADDR=10.254.0.1

NGINX_VERSION=1.13.7-1~stretch

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

KUBERNETES_PORT_443_TCP_PORT=443

NJS_VERSION=1.13.7.0.1.15-1~stretch

KUBERNETES_PORT_443_TCP_PROTO=tcp

MY_SERVICE_SERVICE_PORT=80

MY_SERVICE_PORT=tcp://10.254.110.249:80

SPECIAL_LEVEL_KEY=very

MY_SERVICE_PORT_80_TCP_ADDR=10.254.110.249

KUBERNETES_PORT_443_TCP=tcp://10.254.0.1:443

KUBERNETES_SERVICE_PORT_HTTPS=443

KUBERNETES_SERVICE_HOST=10.254.0.1

MY_SERVICE_PORT_80_TCP_PORT=80

PWD=/

MY_SERVICE_PORT_80_TCP_PROTO=tcp

ConfigMap的限制条件

ConfigMap必须在Pod之前创建才能被使用。
ConfigMap可以定义其属于哪个Namspece，只有在同一个Namespace中的pod才能引用。

删除Pod

有时候deployment、rs、rc、services都为0，但是Pod确存在着。则重启kubelet服务即可。

$ systemctl restart kubelet

补充

# 列出当前节点名

kubectl get node

NAME STATUS AGE

127.0.0.1 Ready 6d

# 已知当前节点名为127.0.0.1,用如下命令即可获得该节点上所有运行节点

$ curl localhost:8080/api/v1/proxy/nodes/127.0.0.1/pods

{"kind":"PodList","apiVersion":"v1","metadata":{},"items":null}

报错

$ sudo kubectl create -f file.yaml

YAML error: found character that cannot start any token

# or

error:yaml: line 15: found a tab character that violate indentation

#file.yaml不可用tab键来空格

$ sudo kubectl create -f mysql-rc.yaml

error: error validating "mysql-rc.yaml": error validating data: [found invalid field app for v1.ObjectMeta, found invalid field value for v1.Container]; if you choose to ignore these errors, turn validation off with --validate=false

---------------------

# kubectl get pod --all-namespaces

NAMESPACE NAME READY STATUS RESTARTS AGE

default my-nginx-379829228-b796w 1/1 Running 0 12m

kube-system kubernetes-dashboard-2397086622-46tvx 0/1 ContainerCreating 0 8s

[root@node01 ~]# kubectl logs -f kubernetes-dashboard-2397086622-46tvx --namespace=kube-system

Using HTTP port: 9090

Using apiserver-host location: http://127.0.0.1:8080

Creating API server client for http://127.0.0.1:8080

Error while initializing connection to Kubernetes apiserver. This most likely means that the cluster is misconfigured (e.g., it has invalid apiserver certificates or service accounts configuration) or the --apiserver-host param points to a server that does not exist. Reason: Get http://127.0.0.1:8080/version: dial tcp 127.0.0.1:8080: getsockopt: connection refused

Refer to the troubleshooting guide for more information: https://github.com/kubernetes/dashboard/blob/master/docs/user-guide/troubleshooting.md

我们最好不要越过RC而直接创建Pod,因为Replication Controller会通过RC管理Pod副本。实现自动创建、补足、替换、删除Pod副本，大大提高系统的容灾能力

重新调度(Rescheduling)
弹性伸缩(Scaling)
滚动更新(Rolling Updates)

转载于:https://www.cnblogs.com/huangzhenyou/p/8066145.html

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