K8S的学习之旅-基础知识

使用minikube创建集群

  • 启动docker后，启动minikube
C:\Users\Caisi>minikube start
* Microsoft Windows 10 Education 10.0.18363 Build 18363 上的 minikube v1.16.0
* 根据现有的配置文件使用 docker 驱动程序
* Starting control plane node minikube in cluster minikube
* Restarting existing docker container for "minikube" ...
! This container is having trouble accessing https://k8s.gcr.io
* To pull new external images, you may need to configure a proxy: https://minikube.sigs.k8s.io/docs/reference/networking/proxy/
* 正在 Docker 20.10.0 中准备 Kubernetes v1.20.0…
* Verifying Kubernetes components...
* Enabled addons: storage-provisioner, default-storageclass, dashboard
* Done! kubectl is now configured to use "minikube" cluster and "default" namespace by default
  • 查看集群详情
C:\Users\Caisi>kubectl cluster-info
Kubernetes master is running at https://127.0.0.1:55000
KubeDNS is running at https://127.0.0.1:55000/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy
  • 查看结点
C:\Users\Caisi>kubectl get nodes
NAME       STATUS   ROLES                  AGE    VERSION
minikube   Ready    control-plane,master   4d1h   v1.20.0

部署应用

  • 什么是deployments
  1. 应用高可用。deployment提供了一种自我修复机制来解决机器故障维护问题
  2. deployment就像是Hadoop的zookeeper一样，监控各个应用，如果某个节点宕掉了，deployment将在集群的另外一个节点上部署。这就是想要删除应用必须先删除deployment的应用，否则节点的应用被删除后，deployment将启动故障修复应用。
  • 创建deployment
C:\Users\Caisi>kubectl create deployment kubernetes-bootcamp --image=gcr.io/google-samples/kubernetes-bootcamp:v1
deployment.apps/kubernetes-bootcamp created
# 查看deployments
C:\Users\Caisi>kubectl get deployments
NAME                  READY   UP-TO-DATE   AVAILABLE   AGE
hello-minikube        4/4     4            4           3d23h
kubernetes-bootcamp   0/1     1            0           2m29s
# 查看pods，不出意外，还是拉取失败了
C:\Users\Caisi>kubectl get pods
NAME                                   READY   STATUS             RESTARTS   AGE
hello-minikube-8947b65df-2n7x9         1/1     Running            2          3d18h
hello-minikube-8947b65df-g78l7         1/1     Running            3          3d23h
hello-minikube-8947b65df-ptzbp         1/1     Running            2          3d17h
hello-minikube-8947b65df-ql5vm         1/1     Running            2          3d17h
kubernetes-bootcamp-57978f5f5d-pwvs7   0/1     ImagePullBackOff   0          2m11s
# 查看pods详情
C:\Users\Caisi>kubectl describe pods kubernetes-bootcamp-57978f5f5d-pwvs7
Normal   Pulling    2m35s (x4 over 4m41s)  kubelet            Pulling image "gcr.io/google-samples/kubernetes-bootcamp:v1"
Warning  Failed     2m20s (x4 over 4m25s)  kubelet            Failed to pull image "gcr.io/google-samples/kubernetes-bootcamp:v1": rpc error: code = Unknown desc = Error response from daemon: Get https://gcr.io/v2/: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
Warning  Failed     2m20s (x4 over 4m25s)  kubelet            Error: ErrImagePull
Normal   BackOff    111s (x6 over 4m25s)   kubelet            Back-off pulling image "gcr.io/google-samples/kubernetes-bootcamp:v1"
Warning  Failed     97s (x7 over 4m25s)    kubelet            Error: ImagePullBackOff

# 删除deployments和pods，换阿里云的kubernetes-bootcamp镜像

阿里云的kubernetes-bootcamp在线镜像

# 这里的镜像可以是本地的docker镜像，也可以是远程的docker hub上的镜像，也可以是在线的url镜像
C:\Users\Caisi>kubectl create deployment kubernetes-bootcamp --image=registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v1
deployment.apps/kubernetes-bootcamp created

C:\Users\Caisi>kubectl get pods
NAME                                  READY   STATUS              RESTARTS   AGE
hello-minikube-8947b65df-2n7x9        1/1     Running             2          3d18h
hello-minikube-8947b65df-g78l7        1/1     Running             3          4d
hello-minikube-8947b65df-ptzbp        1/1     Running             2          3d18h
hello-minikube-8947b65df-ql5vm        1/1     Running             2          3d18h
kubernetes-bootcamp-ccd8cdbf6-ftz2n   0/1     ContainerCreating   0          5s

C:\Users\Caisi>kubectl get pods
NAME                                  READY   STATUS    RESTARTS   AGE
hello-minikube-8947b65df-2n7x9        1/1     Running   2          3d18h
hello-minikube-8947b65df-g78l7        1/1     Running   3          4d
hello-minikube-8947b65df-ptzbp        1/1     Running   2          3d18h
hello-minikube-8947b65df-ql5vm        1/1     Running   2          3d18h
kubernetes-bootcamp-ccd8cdbf6-ftz2n   1/1     Running   0          13m

查看部署的程序

  1. 首先需要明确一点的是刚刚创建的kubernetes-bootcamp只能进行内部之间的访问，也可以通过kubectl API进行访问。
  2. 下面将开启一个代理来让外部可以进行访问。
  • 开启代理
# 注意：保持此窗口
C:\Users\Caisi>kubectl proxy
Starting to serve on 127.0.0.1:8001
  • 通过API查询版本
C:\Users\Caisi>curl http://localhost:8001/version
{
  "major": "1",
  "minor": "20",
  "gitVersion": "v1.20.0",
  "gitCommit": "af46c47ce925f4c4ad5cc8d1fca46c7b77d13b38",
  "gitTreeState": "clean",
  "buildDate": "2020-12-08T17:51:19Z",
  "goVersion": "go1.15.5",
  "compiler": "gc",
  "platform": "linux/amd64"
}
  • 获取pod名称，并保存到环境变量中
# 注意：这里在Windows下要使用powershell工具
PS C:\Users\Caisi> $env:POD_NAME=kubectl get pods -o go-template --template '{{range .items}}{{.metadata.name}}{{end}}'

PS C:\Users\Caisi> $env:POD_NAME
kubernetes-bootcamp-ccd8cdbf6-ftz2n

C:\Users\Caisi> kubectl get pods
NAME                                  READY   STATUS    RESTARTS   AGE
kubernetes-bootcamp-ccd8cdbf6-ftz2n   1/1     Running   0          47m

pod和工作节点

什么是pod？

  1. Pod是kubernetes抽象出来的，表示一组一个或多个应用程序容器，以及一些容器的一些共享资源。如，共享存储、网络IP、运行信息。
  2. Pod是kubernetes平台上的原子单元。当创建deployment是首先会在其中创建包含容器的Pod，而不是直接创建容器。

什么是工作节点

  • 通常一个pod总是运行在工作节点上。而工作节点又由主节点管理。

查看应用信息

  • 查看Pod
C:\Users\Caisi>kubectl get pods
NAME                                  READY   STATUS    RESTARTS   AGE
kubernetes-bootcamp-ccd8cdbf6-ftz2n   1/1     Running   0          97m
  • 查看Pod详情
C:\Users\Caisi>kubectl describe pods
Name:         kubernetes-bootcamp-ccd8cdbf6-ftz2n
Namespace:    default
Priority:     0
Node:         minikube/192.168.49.2
Start Time:   Thu, 21 Jan 2021 11:19:41 +0800
Labels:       app=kubernetes-bootcamp
              pod-template-hash=ccd8cdbf6
Annotations:  <none>
Status:       Running
IP:           172.17.0.9
IPs:
  IP:           172.17.0.9
Controlled By:  ReplicaSet/kubernetes-bootcamp-ccd8cdbf6
Containers:
  kubernetes-bootcamp:
    Container ID:   docker://6f05bd5069e740c331f5d65ebb770745d7f91919733dacaf81e434563308c367
    Image:          registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v1
    Image ID:       docker-pullable://registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp@sha256:34e5a47d302ee20039e5f0eb1e2f49785dafee3d97cac704befba6c1c7c938fc
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Thu, 21 Jan 2021 11:20:13 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-47bf2 (ro)
Conditions:
  Type              Status
  Initialized       True
  Ready             True
  ContainersReady   True
  PodScheduled      True
Volumes:
  default-token-47bf2:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-47bf2
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                 node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:          <none>
  • 使用curl查看应用输出
# 这里需要开启代理（如果您已经关闭，重新开启：kubectl proxy）

# 这里直接使用kubernetes-bootcamp-ccd8cdbf6-ftz2n的默认80端口无法访问，在GitHub issue上看到可以用8080端口实现
C:\Users\Caisi>curl http://localhost:8001/api/v1/namespaces/default/pods/kubernetes-bootcamp-ccd8cdbf6-ftz2n:8080/proxy/
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-ccd8cdbf6-ftz2n | v=1

Issue with k8s.io/docs/tutorials/kubernetes-basics/explore/explore-interactive/#18079

  • 查看日志
# 这里使用了上一节的环境变量，也可以直接用kubernetes-bootcamp-ccd8cdbf6-ftz2n替换
PS C:\Users\Caisi> kubectl logs $env:POD_NAME
Kubernetes Bootcamp App Started At: 2021-01-21T03:20:14.032Z | Running On:  kubernetes-bootcamp-ccd8cdbf6-ftz2n

Running On: kubernetes-bootcamp-ccd8cdbf6-ftz2n | Total Requests: 1 | App Uptime: 7002.931 seconds | Log Time: 2021-01-21T05:16:56.963Z
  • 列出Pod的所有环境变量
PS C:\Users\Caisi> kubectl exec $env:POD_NAME env
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=kubernetes-bootcamp-ccd8cdbf6-ftz2n
HELLO_MINIKUBE_SERVICE_HOST=10.102.25.156
HELLO_MINIKUBE_PORT_8080_TCP=tcp://10.102.25.156:8080
KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443
HELLO_MINIKUBE_SERVICE_PORT=8080
HELLO_MINIKUBE_PORT_8080_TCP_PROTO=tcp
HELLO_MINIKUBE_PORT_8080_TCP_PORT=8080
KUBERNETES_SERVICE_PORT=443
KUBERNETES_SERVICE_PORT_HTTPS=443
KUBERNETES_PORT_443_TCP_PORT=443
HELLO_MINIKUBE_PORT=tcp://10.102.25.156:8080
HELLO_MINIKUBE_PORT_8080_TCP_ADDR=10.102.25.156
KUBERNETES_SERVICE_HOST=10.96.0.1
KUBERNETES_PORT=tcp://10.96.0.1:443
KUBERNETES_PORT_443_TCP_PROTO=tcp
KUBERNETES_PORT_443_TCP_ADDR=10.96.0.1
NPM_CONFIG_LOGLEVEL=info
NODE_VERSION=6.3.1
HOME=/root
  • 开启一个bash会话，相当于进入虚拟机的shell中
PS C:\Users\Caisi> kubectl exec -ti $env:POD_NAME bash
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
root@kubernetes-bootcamp-ccd8cdbf6-ftz2n:/#
  • 查看Node.js应用代码
root@kubernetes-bootcamp-ccd8cdbf6-ftz2n:/# cat server.js
var http = require('http');
var requests=0;
var podname= process.env.HOSTNAME;
var startTime;
var host;
var handleRequest = function(request, response) {
  response.setHeader('Content-Type', 'text/plain');
  response.writeHead(200);
  response.write("Hello Kubernetes bootcamp! | Running on: ");
  response.write(host);
  response.end(" | v=1\n");
  console.log("Running On:" ,host, "| Total Requests:", ++requests,"| App Uptime:", (new Date() - startTime)/1000 , "seconds", "| Log Time:",new Date());
}
var www = http.createServer(handleRequest);
www.listen(8080,function () {
    startTime = new Date();;
    host = process.env.HOSTNAME;
    console.log ("Kubernetes Bootcamp App Started At:",startTime, "| Running On: " ,host, "\n" );
});
  • 查看Node.js应用是否在运行
# 从这里也可以看出pod内部对应的端口为8080
root@kubernetes-bootcamp-ccd8cdbf6-ftz2n:/# curl localhost:8080
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-ccd8cdbf6-ftz2n | v=1
  • 退出bash使用：exit。这一点与docker进入容器相似。

使用services公开暴露应用

什么是service？

  • kubernetes中的service是一种抽象概念，它定义Pod的逻辑集和访问Pod的协议。
  • service是为了解决工作节点挂掉后Pod也会消亡的问题，以保证程序正常运行。

service的暴露方式

  1. clusterIP（默认）：在集群的内部IP上公开service。这种方式只能从集群内访问。
  2. NodePort：使用NAT在集群中每个选定Node的相同端口上公开service。这种方式可以使用:从集群外部访问service。
  3. LoadBalancer:创建一个外部负载均衡器，为service分配一个固定的外部IP。
  4. externalName：通过返回带有该名称的CNAME记录，使用任意名称公开Service。不使用代理。

service和label

  • service匹配一组pod是使用label和selector，label是附加在对象上的键/值对。

暴露应用

  • 使用expose命令暴露NodePort类型
C:\Users\Caisi>kubectl expose deployment/kubernetes-bootcamp --type="NodePort" --port 8080
service/kubernetes-bootcamp exposed

C:\Users\Caisi>kubectl get services
NAME                  TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
kubernetes            ClusterIP   10.96.0.1      <none>        443/TCP          4d5h
kubernetes-bootcamp   NodePort    10.108.3.185   <none>        8080:31491/TCP   20s
  • 使用curl从外部访问程序(这里又有一个docker desktop的坑了)
C:\Users\Caisi>curl 127.0.0.1:31491
curl: (7) Failed to connect to 127.0.0.1 port 31491: Connection refused

Failed to connect to 127.0.0.1 port 50502: Connection refused #8651:
NodePort deployments don’t work with Docker Desktop, unfortunately. Only with Docker Engine.

没有找到合适的解决方法，下面换tunnel暴露应用
# 开启tunnel，保存窗口状态
PS C:\Users\Caisi> minikube tunnel
* Starting tunnel for service kubernetes-bootcamp.
  • 使用LoadBalancer暴露
C:\Users\Caisi>
service/kubernetes-bootcamp exposed

C:\Users\Caisi>kubectl get svc
NAME                  TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
kubernetes            ClusterIP      10.96.0.1      <none>        443/TCP          4d6h
kubernetes-bootcamp   LoadBalancer   10.96.125.12   127.0.0.1     8080:30530/TCP   21s

C:\Users\Caisi>curl 127.0.0.1:8080
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-ccd8cdbf6-ftz2n | v=1

# 如果没有开启tunnel，EXTERNAL-IP为pending等待
C:\Users\Caisi>kubectl get svc
NAME                  TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
kubernetes            ClusterIP      10.96.0.1      <none>        443/TCP          4d6h
kubernetes-bootcamp   LoadBalancer   10.96.125.12   <pending>     8080:30530/TCP   14m
  1. 这种方式每个服务将获得自己的外部IP。
  2. 这种方式有点类似与
C:\Users\Caisi>minikube service kubernetes-bootcamp --url
* Starting tunnel for service kubernetes-bootcamp.
|-----------|---------------------|-------------|------------------------|
| NAMESPACE |        NAME         | TARGET PORT |          URL           |
|-----------|---------------------|-------------|------------------------|
| default   | kubernetes-bootcamp |             | http://127.0.0.1:63528 |
|-----------|---------------------|-------------|------------------------|
http://127.0.0.1:63528 

# 另外一个窗口
C:\Users\Caisi>curl 127.0.0.1:49187
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-ccd8cdbf6-ftz2n | v=1
  • 可以使用label查看service或pod信息
# 这里查看的默认label为app=kubernetes-bootcamp
C:\Users\Caisi>kubectl describe deployment
Name:                   kubernetes-bootcamp
Namespace:              default
CreationTimestamp:      Thu, 21 Jan 2021 11:19:41 +0800
Labels:                 app=kubernetes-bootcamp
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               app=kubernetes-bootcamp
Replicas:               1 desired | 1 updated | 1 total | 1 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=kubernetes-bootcamp
  Containers:
   kubernetes-bootcamp:
    Image:        registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v1
    Port:         <none>
    Host Port:    <none>
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   kubernetes-bootcamp-ccd8cdbf6 (1/1 replicas created)
Events:          <none>

C:\Users\Caisi>kubectl get pods -l app=kubernetes-bootcamp
NAME                                  READY   STATUS    RESTARTS   AGE
kubernetes-bootcamp-ccd8cdbf6-ftz2n   1/1     Running   0          4h43m

C:\Users\Caisi>kubectl get services -l app=kubernetes-bootcamp
NAME                  TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
kubernetes-bootcamp   LoadBalancer   10.96.125.12   127.0.0.1     8080:30530/TCP   29m
  • 也可以添加新的标签，以附加的方式，下面对pod添加一个标签
# 这里已经存在一个app的键了
C:\Users\Caisi>kubectl label pod kubernetes-bootcamp-ccd8cdbf6-ftz2n app=v1
error: 'app' already has a value (kubernetes-bootcamp), and --overwrite is false

C:\Users\Caisi>kubectl label pod kubernetes-bootcamp-ccd8cdbf6-ftz2n run=v1
pod/kubernetes-bootcamp-ccd8cdbf6-ftz2n labeled

C:\Users\Caisi>kubectl describe pods kubernetes-bootcamp-ccd8cdbf6-ftz2n
Name:         kubernetes-bootcamp-ccd8cdbf6-ftz2n
Namespace:    default
Priority:     0
Node:         minikube/192.168.49.2
Start Time:   Thu, 21 Jan 2021 11:19:41 +0800
Labels:       app=kubernetes-bootcamp
              pod-template-hash=ccd8cdbf6
              run=v1
Annotations:  <none>
Status:       Running
IP:           172.17.0.9
IPs:
···


C:\Users\Caisi>kubectl get pods -l run=v1
NAME                                  READY   STATUS    RESTARTS   AGE
kubernetes-bootcamp-ccd8cdbf6-ftz2n   1/1     Running   0          4h51m

注：在这里添加的标签是pod的，所以查看service不能使用此标签，因为service中没有次标签。

  • 删除服务
C:\Users\Caisi>kubectl get services
NAME                  TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
kubernetes            ClusterIP      10.96.0.1      <none>        443/TCP          4d6h
kubernetes-bootcamp   LoadBalancer   10.96.125.12   127.0.0.1     8080:30530/TCP   44m

C:\Users\Caisi>kubectl delete service -l app=kubernetes-bootcamp
service "kubernetes-bootcamp" deleted

C:\Users\Caisi>kubectl get services
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   4d6h

# 集群外部无法访问应用
C:\Users\Caisi>curl 127.0.0.1:8080
curl: (7) Failed to connect to 127.0.0.1 port 8080: Connection refused

# 使用kubectlAPI访问集群中应用正常运行
C:\Users\Caisi>kubectl exec -ti kubernetes-bootcamp-ccd8cdbf6-ftz2n curl localhost:8080
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-ccd8cdbf6-ftz2n | v=1

缩放应用

为什么需要缩放？

deployment只创建了一个Pod，当流量增加时，就需要扩容应用程序以满足用户需求了。

其实际是通过改变deployment中的副本数量来实现的。

当pod数量为0时，deployment上的颇多将终止。

  • 使用scale扩展为四个副本
C:\Users\Caisi>kubectl scale deployments/kubernetes-bootcamp --replicas=4
deployment.apps/kubernetes-bootcamp scaled

C:\Users\Caisi>kubectl get rs
NAME                            DESIRED   CURRENT   READY   AGE
kubernetes-bootcamp-ccd8cdbf6   4         4         4       5h42m

C:\Users\Caisi>kubectl get pods -o wide
NAME                                  READY   STATUS    RESTARTS   AGE     IP           NODE       NOMINATED NODE   READINESS GATES
kubernetes-bootcamp-ccd8cdbf6-8z74q   1/1     Running   0          39s     172.17.0.2   minikube   <none>           <none>
kubernetes-bootcamp-ccd8cdbf6-ftz2n   1/1     Running   0          5h42m   172.17.0.9   minikube   <none>           <none>
kubernetes-bootcamp-ccd8cdbf6-q5mh4   1/1     Running   0          39s     172.17.0.4   minikube   <none>           <none>
kubernetes-bootcamp-ccd8cdbf6-rmjqc   1/1     Running   0          39s     172.17.0.3   minikube   <none>           <none>
  • 缩减副本为2
C:\Users\Caisi>kubectl scale deployment/kubernetes-bootcamp --replicas=2
deployment.apps/kubernetes-bootcamp scaled

C:\Users\Caisi>kubectl get service
NAME                  TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
kubernetes            ClusterIP      10.96.0.1      <none>        443/TCP          4d7h
kubernetes-bootcamp   LoadBalancer   10.96.228.52   <pending>     8080:31177/TCP   4m30s

C:\Users\Caisi>kubectl get pods -o wide
NAME                                  READY   STATUS        RESTARTS   AGE     IP           NODE       NOMINATED NODE   READINESS GATES
kubernetes-bootcamp-ccd8cdbf6-8xc6c   1/1     Terminating   0          9m19s   172.17.0.4   minikube   <none>           <none>
kubernetes-bootcamp-ccd8cdbf6-fp5vz   1/1     Running       0          13m     172.17.0.5   minikube   <none>           <none>
kubernetes-bootcamp-ccd8cdbf6-hkdj8   1/1     Terminating   0          9m19s   172.17.0.3   minikube   <none>           <none>
kubernetes-bootcamp-ccd8cdbf6-ksfzf   1/1     Running       0          9m19s   172.17.0.2   minikube   <none>           <none>

C:\Users\Caisi>kubectl get pods
NAME                                  READY   STATUS        RESTARTS   AGE
kubernetes-bootcamp-ccd8cdbf6-8xc6c   1/1     Terminating   0          9m26s
kubernetes-bootcamp-ccd8cdbf6-fp5vz   1/1     Running       0          13m
kubernetes-bootcamp-ccd8cdbf6-hkdj8   1/1     Terminating   0          9m26s
kubernetes-bootcamp-ccd8cdbf6-ksfzf   1/1     Running       0          9m26s

更新应用，滚动更新

  • 滚动更新允许应用程序从一个环境提升到另一个环境、回滚到以前的版本、持续集成和持续交付。

  • 更新到v2

C:\Users\Caisi>kubectl set image deployments/kubernetes-bootcamp kubernetes-bootcamp=jocatalin/kubernetes-bootcamp:v2
deployment.apps/kubernetes-bootcamp image updated
# 容器创建中
C:\Users\Caisi>kubectl get pods
NAME                                  READY   STATUS              RESTARTS   AGE
kubernetes-bootcamp-769746fd4-zbvvs   0/1     ContainerCreating   0          21s
kubernetes-bootcamp-ccd8cdbf6-fp5vz   1/1     Running             0          22m
kubernetes-bootcamp-ccd8cdbf6-ksfzf   1/1     Running             0          18m
# 创建成功后，就得pod将终止
C:\Users\Caisi>kubectl get pods
NAME                                  READY   STATUS        RESTARTS   AGE
kubernetes-bootcamp-769746fd4-qf22h   1/1     Running       0          27s
kubernetes-bootcamp-769746fd4-zbvvs   1/1     Running       0          75s
kubernetes-bootcamp-ccd8cdbf6-fp5vz   1/1     Terminating   0          23m
kubernetes-bootcamp-ccd8cdbf6-ksfzf   1/1     Terminating   0          19m
# 确认升级成功
C:\Users\Caisi>kubectl rollout status deployments/kubernetes-bootcamp
deployment "kubernetes-bootcamp" successfully rolled out

# pod的image为v2版本
C:\Users\Caisi>kubectl describe pods
···
Containers:
  kubernetes-bootcamp:
    Container ID:   docker://b46d0b7c1059485c241d674a9d646cd923aa55619ac30a7ee3e377ec85503b1a
    Image:          jocatalin/kubernetes-bootcamp:v2
    Image ID:       docker-pullable://jocatalin/kubernetes-bootcamp@sha256:fb1a3ced00cecfc1f83f18ab5cd14199e30adc1b49aa4244f5d65ad3f5feb2a5
    Port:           <none>
    Host Port:      <none>
···
Controlled By:  ReplicaSet/kubernetes-bootcamp-769746fd4
Containers:
  kubernetes-bootcamp:
    Container ID:   docker://6bd647432eaab9573c6d68210a79999804f452f50e7ce8abdd6192193840ad1c
    Image:          jocatalin/kubernetes-bootcamp:v2
    Image ID:       docker-pullable://jocatalin/kubernetes-bootcamp@sha256:fb1a3ced00cecfc1f83f18ab5cd14199e30adc1b49aa4244f5d65ad3f5feb2a5
    Port:           <none>
    Host Port:      <none>
···
  • 升级失败
# 这里升级到v10版本
C:\Users\Caisi>kubectl set image deployments/kubernetes-bootcamp kubernetes-bootcamp=registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v10
deployment.apps/kubernetes-bootcamp image updated

C:\Users\Caisi>kubectl get deployment
NAME                  READY   UP-TO-DATE   AVAILABLE   AGE
kubernetes-bootcamp   2/2     1            2           33m
# 镜像拉取失败
C:\Users\Caisi>kubectl get pods
NAME                                  READY   STATUS         RESTARTS   AGE
kubernetes-bootcamp-769746fd4-qf22h   1/1     Running        0          10m
kubernetes-bootcamp-769746fd4-zbvvs   1/1     Running        0          11m
kubernetes-bootcamp-799d5964b-mzvcg   0/1     ErrImagePull   0          37s

C:\Users\Caisi>kubectl get pods
NAME                                  READY   STATUS             RESTARTS   AGE
kubernetes-bootcamp-769746fd4-qf22h   1/1     Running            0          10m
kubernetes-bootcamp-769746fd4-zbvvs   1/1     Running            0          11m
kubernetes-bootcamp-799d5964b-mzvcg   0/1     ImagePullBackOff   0          47s
# 有一个v10的image版本拉取失败
C:\Users\Caisi>kubectl describe pods
···
Controlled By:  ReplicaSet/kubernetes-bootcamp-769746fd4
Containers:
  kubernetes-bootcamp:
    Container ID:   docker://b46d0b7c1059485c241d674a9d646cd923aa55619ac30a7ee3e377ec85503b1a
    Image:          jocatalin/kubernetes-bootcamp:v2
    Image ID:       docker-pullable://jocatalin/kubernetes-bootcamp@sha256:fb1a3ced00cecfc1f83f18ab5cd14199e30adc1b49aa4244f5d65ad3f5feb2a5
    Port:           <none>
    Host Port:      <none>
···
Controlled By:  ReplicaSet/kubernetes-bootcamp-769746fd4
Containers:
  kubernetes-bootcamp:
    Container ID:   docker://6bd647432eaab9573c6d68210a79999804f452f50e7ce8abdd6192193840ad1c
    Image:          jocatalin/kubernetes-bootcamp:v2
    Image ID:       docker-pullable://jocatalin/kubernetes-bootcamp@sha256:fb1a3ced00cecfc1f83f18ab5cd14199e30adc1b49aa4244f5d65ad3f5feb2a5
    Port:           <none>
    Host Port:      <none>
···
Controlled By:  ReplicaSet/kubernetes-bootcamp-799d5964b
Containers:
  kubernetes-bootcamp:
    Container ID:
    Image:          registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v10
    Image ID:
    Port:           <none>
···
Normal   Scheduled  65s                default-scheduler  Successfully assigned default/kubernetes-bootcamp-799d5964b-mzvcg to minikube
Normal   Pulling    21s (x3 over 64s)  kubelet            Pulling image "registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v10"
Warning  Failed     20s (x3 over 63s)  kubelet            Failed to pull image "registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v10": rpc error: code = Unknown desc = Error response from daemon: manifest for registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v10 not found: manifest unknown: manifest unknown
Warning  Failed     20s (x3 over 63s)  kubelet            Error: ErrImagePull
Normal   BackOff    5s (x3 over 62s)   kubelet            Back-off pulling image "registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v10"
Warning  Failed     5s (x3 over 62s)   kubelet            Error: ImagePullBackOff
  • 回滚
# 使用undo进行回滚
C:\Users\Caisi>kubectl rollout undo deployments/kubernetes-bootcamp
deployment.apps/kubernetes-bootcamp rolled back

C:\Users\Caisi>kubectl get pods
NAME                                  READY   STATUS        RESTARTS   AGE
kubernetes-bootcamp-769746fd4-qf22h   1/1     Running       0          13m
kubernetes-bootcamp-769746fd4-zbvvs   1/1     Running       0          14m
kubernetes-bootcamp-799d5964b-mzvcg   0/1     Terminating   0          3m8s
# 这里v10版本已经没有了
C:\Users\Caisi>kubectl describe pods
···
Containers:
  kubernetes-bootcamp:
    Container ID:   docker://b46d0b7c1059485c241d674a9d646cd923aa55619ac30a7ee3e377ec85503b1a
    Image:          jocatalin/kubernetes-bootcamp:v2
    Image ID:       docker-pullable://jocatalin/kubernetes-bootcamp@sha256:fb1a3ced00cecfc1f83f18ab5cd14199e30adc1b49aa4244f5d65ad3f5feb2a5
    Port:           <none>
    Host Port:      <none>
···
Containers:
  kubernetes-bootcamp:
    Container ID:   docker://6bd647432eaab9573c6d68210a79999804f452f50e7ce8abdd6192193840ad1c
    Image:          jocatalin/kubernetes-bootcamp:v2
    Image ID:       docker-pullable://jocatalin/kubernetes-bootcamp@sha256:fb1a3ced00cecfc1f83f18ab5cd14199e30adc1b49aa4244f5d65ad3f5feb2a5
    Port:           <none>
    Host Port:      <none>
···
Pod 'kubernetes-bootcamp-799d5964b-mzvcg': error 'pods "kubernetes-bootcamp-799d5964b-mzvcg" not found', but found events.
Events:
  Type     Reason     Age                   From               Message
  ----     ------     ----                  ----               -------
  Normal   Scheduled  3m20s                 default-scheduler  Successfully assigned default/kubernetes-bootcamp-799d5964b-mzvcg to minikube
  Normal   Pulling    114s (x4 over 3m19s)  kubelet            Pulling image "registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v10"
  Warning  Failed     113s (x4 over 3m18s)  kubelet            Failed to pull image "registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v10": rpc error: code = Unknown desc = Error response from daemon: manifest for registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v10 not found: manifest unknown: manifest unknown
  Warning  Failed     113s (x4 over 3m18s)  kubelet            Error: ErrImagePull
  Normal   BackOff    90s (x6 over 3m17s)   kubelet            Back-off pulling image "registry.cn-beijing.aliyuncs.com/typ/kubernetes-bootcamp:v10"
  Warning  Failed     76s (x7 over 3m17s)   kubelet            Error: ImagePullBackOff

总结

  1. 这一节学习了创建minikube集群、部署Node.js应用、一些基本的查看pod的命令、公开暴露应用、缩放应用、更新与回滚应用。
  2. 值得注意的是docker desktop不支持service的NodePort模式这个坑，不过Linux的docker engine是支持的。
  3. 还有就是label的作用。
  4. 通过这次的了解，对deployment和pod，以及service又有了一些新的看法。
# kubernetes # docker
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