正文
一、创建集群
1.1 通过minikube搭建集群
假设已经预先安装好了minikube，执行如下命令初始化一个单节点的集群：
minikube start
试试k8s集群是否初始化成功：
kubectl version
然后可以查看集群的信息和节点信息：
$ kubectl cluster-info Kubernetes control plane is running at https://172.17.0.24:8443 KubeDNS is running at https://172.17.0.24:8443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy $ kubectl get nodes NAME STATUS ROLES AGE VERSION minikube Ready control-plane,master 8m25s v1.20.2
二、部署应用
在部署应用之前，我们查看pod的信息：
$ kubectl get pods No resources found in default namespace.
然后我们使用如下命令部署一个应用并查看应用的信息：
$ kubectl create deployment kubernetes-bootcamp --image=gcr.io/google-samples/kubernetes-bootcamp:v1 deployment.apps/kubernetes-bootcamp created $ kubectl get deployments NAME READY UP-TO-DATE AVAILABLE AGE kubernetes-bootcamp 1/1 1 1 53s $ kubectl get pods NAME READY STATUS RESTARTS AGE kubernetes-bootcamp-57978f5f5d-wk8kg 1/1 Running 0 62s
应用虽然部署完成了，但是默认情况下我们只能在集群内部才能访问pod（参考下面3.3节内容），命令行curl访问应用的接口则是属于集群外部访问pod了，所以要实现curl接口需要做如下的设置：
方案一
新启动一个该节点的命令行，执行如下命令：
$ kubectl proxy Starting to serve on 127.0.0.1:8001
表示节点的9001端口能访问到集群中的pod了：
$ curl http://localhost:8001/version { "major": "1", "minor": "20", "gitVersion": "v1.20.2", "gitCommit": "faecb196815e248d3ecfb03c680a4507229c2a56", "gitTreeState": "clean", "buildDate": "2021-01-13T13:20:00Z", "goVersion": "go1.15.5", "compiler": "gc", "platform": "linux/amd64" }
方案二
主动将应用的端口暴露出去（参考如下第四章节内容）：
$ kubectl expose deployment/kubernetes-bootcamp --type="NodePort" --port 8080 service/kubernetes-bootcamp exposed $ kubectl get services NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 15m kubernetes-bootcamp NodePort 10.106.152.94 <none> 8080:31281/TCP 12s $ curl http://localhost:31281/version Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-57978f5f5d-wk8kg | v=1
三、应用程序探索
应用部署完成后，我们需要通过一些手段来监控和运维我们的应用。
3.1 检查
$ kubectl get pods NAME READY STATUS RESTARTS AGE kubernetes-bootcamp-fb5c67579-q8mrb 1/1 Running 0 26s $ kubectl describe pods Name: kubernetes-bootcamp-fb5c67579-q8mrb Namespace: default Priority: 0 Node: minikube/172.17.0.129 Start Time: Tue, 08 Feb 2022 08:39:44 +0000 Labels: app=kubernetes-bootcamp pod-template-hash=fb5c67579 Annotations: <none> Status: Running IP: 172.18.0.6 IPs: IP: 172.18.0.6 Controlled By: ReplicaSet/kubernetes-bootcamp-fb5c67579 Containers: kubernetes-bootcamp: Container ID: docker://e243e942198e2d1a1d37db5820e210ada432221c1ca915b7859fbc3af5543d72 Image: gcr.io/google-samples/kubernetes-bootcamp:v1 Image ID: docker-pullable://jocatalin/kubernetes-bootcamp@sha256:0d6b8ee63bb57c5f5b6156f446b3bc3b3c143d233037f3a2f00e279c8fcc64af Port: 8080/TCP Host Port: 0/TCP State: Running Started: Tue, 08 Feb 2022 08:39:49 +0000 Ready: True Restart Count: 0 Environment: <none> Mounts: /var/run/secrets/kubernetes.io/serviceaccount from default-token-kqhb5 (ro) Conditions: Type Status Initialized True Ready True ContainersReady True PodScheduled True Volumes: default-token-kqhb5: Type: Secret (a volume populated by a Secret) SecretName: default-token-kqhb5 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: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled 3m38s default-scheduler Successfully assigned default/kubernetes-bootcamp-fb5c67579-q8mrb to minikube Normal Pulled 3m34s kubelet Container image "gcr.io/google-samples/kubernetes-bootcamp:v1" already present on machine Normal Created 3m34s kubelet Created container kubernetes-bootcamp Normal Started 3m33s kubelet Started container kubernetes-bootcamp
3.2 查看日志
使用容器名称查看容器中的运行日志。
$ kubectl logs kubernetes-bootcamp-fb5c67579-q8mrb Kubernetes Bootcamp App Started At: 2022-02-08T08:39:49.327Z | Running On: kubernetes-bootcamp-fb5c67579-q8mrb
3.3容器内执行命令
# 进入容器内部并执行bash命令 $ kubectl exec -ti kubernetes-bootcamp-fb5c67579-q8mrb -- bash
# 测试容器内部命令 root@kubernetes-bootcamp-fb5c67579-q8mrb:/# pwd
# 容器内部curl访问pod root@kubernetes-bootcamp-fb5c67579-q8mrb:/# curl localhost:8080 Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-fb5c67579-q8mrb | v=1
# 退出容器 root@kubernetes-bootcamp-fb5c67579-q8mrb:/# exit exit
四、访问应用
在第二章中我们介绍了，部署完成pod之后，默认情况下只能在集群内部才能访问到该pod，想要通过外部访问该pod，就一定要使用Service。
我们如上已经创建了service，并将其暴露在外了，此处不再赘述
我们可以通过使用label来筛选想要查询的资源信息：
$ kubectl get pods -l app=kubernetes-bootcamp NAME READY STATUS RESTARTS AGE kubernetes-bootcamp-fb5c67579-rvbxv 1/1 Running 0 2m15s $ kubectl get services -l app=kubernetes-bootcamp NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes-bootcamp NodePort 10.97.252.94 <none> 8080:31926/TCP 76s
当我们不再需要该service的时候，可以通过如下命令删除，删除后，外部将无法再访问运行的pod。
$ curl localhost:31926 Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-fb5c67579-rvbxv | v=1 $ kubectl delete service -l app=kubernetes-bootcamp service "kubernetes-bootcamp" deleted $ kubectl get services NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 5m13s $ curl localhost:31926 curl: (7) Failed to connect to localhost port 31926: Connection refused
五、扩展应用
当流量有变化的时候，我们就需要动态地对pod进行扩容：
$ kubectl get deployments NAME READY UP-TO-DATE AVAILABLE AGE kubernetes-bootcamp 1/1 1 1 6m10s $ kubectl get rs NAME DESIRED CURRENT READY AGE kubernetes-bootcamp-fb5c67579 1 1 1 6m6s $ kubectl scale deployments/kubernetes-bootcamp --replicas=4 deployment.apps/kubernetes-bootcamp scaled $ kubectl get deployments NAME READY UP-TO-DATE AVAILABLE AGE kubernetes-bootcamp 4/4 4 4 8m32s $ kubectl get rsNAME DESIRED CURRENT READY AGE kubernetes-bootcamp-fb5c67579 4 4 1 7m27s $ kubectl get pods -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES kubernetes-bootcamp-fb5c67579-82nhh 1/1 Running 0 2m13s 172.18.0.8 minikube <none> <none> kubernetes-bootcamp-fb5c67579-96t49 1/1 Running 0 9m6s 172.18.0.5 minikube <none> <none> kubernetes-bootcamp-fb5c67579-jz5vw 1/1 Running 0 2m13s 172.18.0.9 minikube <none> <none> kubernetes-bootcamp-fb5c67579-vfpn8 1/1 Running 0 2m13s 172.18.0.7 minikube <none> <none> $ kubectl describe deployments/kubernetes-bootcamp Name: kubernetes-bootcamp Namespace: default CreationTimestamp: Tue, 08 Feb 2022 09:16:30 +0000 Labels: app=kubernetes-bootcamp Annotations: deployment.kubernetes.io/revision: 1 Selector: app=kubernetes-bootcamp Replicas: 4 desired | 4 updated | 4 total | 4 available | 0 unavailable StrategyType: RollingUpdate MinReadySeconds: 0 RollingUpdateStrategy: 25% max unavailable, 25% max surge Pod Template: Labels: app=kubernetes-bootcamp Containers: kubernetes-bootcamp: Image: gcr.io/google-samples/kubernetes-bootcamp:v1 Port: 8080/TCP Host Port: 0/TCP Environment: <none> Mounts: <none> Volumes: <none> Conditions: Type Status Reason ---- ------ ------ Progressing True NewReplicaSetAvailable Available True MinimumReplicasAvailable OldReplicaSets: <none> NewReplicaSet: kubernetes-bootcamp-fb5c67579 (4/4 replicas created) Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal ScalingReplicaSet 9m45s deployment-controller Scaled up replica set kubernetes-bootcamp-fb5c67579 to 1 Normal ScalingReplicaSet 2m50s deployment-controller Scaled up replica set kubernetes-bootcamp-fb5c67579 to 4
此时我们已经将pod扩展到4个副本了，此时我们在集群外部访问Service，那么请求会被自动地以负载均衡的方式分发到各个pod上。
$ kubectl describe services/kubernetes-bootcamp Name: kubernetes-bootcamp Namespace: default Labels: app=kubernetes-bootcamp Annotations: <none> Selector: app=kubernetes-bootcamp Type: NodePort IP Families: <none> IP: 10.104.229.171 IPs: 10.104.229.171 Port: <unset> 8080/TCP TargetPort: 8080/TCP NodePort: <unset> 30848/TCP Endpoints: 172.18.0.5:8080,172.18.0.7:8080,172.18.0.8:8080 + 1 more... Session Affinity: None External Traffic Policy: Cluster Events: <none> # 如下请求将会被负载均衡地分发到各个pod上 $ curl localhost:30848 Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-fb5c67579-96t49 | v=1 $ curl localhost:30848 Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-fb5c67579-vfpn8 | v=1 $ curl localhost:30848 Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-fb5c67579-jz5vw | v=1 $ curl localhost:30848 Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-fb5c67579-82nhh | v=1
当我们需要缩容的时候也很简单：
$ kubectl scale deployments/kubernetes-bootcamp --replicas=2 deployment.apps/kubernetes-bootcamp scaled $ kubectl get deployments NAME READY UP-TO-DATE AVAILABLE AGE kubernetes-bootcamp 2/2 2 2 17m $ kubectl get pods -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES kubernetes-bootcamp-fb5c67579-82nhh 1/1 Terminating 0 9m38s 172.18.0.8 minikube <none> <none> kubernetes-bootcamp-fb5c67579-96t49 1/1 Running 0 16m 172.18.0.5 minikube <none> <none> kubernetes-bootcamp-fb5c67579-jz5vw 1/1 Running 0 9m38s 172.18.0.9 minikube <none> <none> kubernetes-bootcamp-fb5c67579-vfpn8 1/1 Terminating 0 9m38s 172.18.0.7 minikube <none> <none> $ kubectl get pods -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES kubernetes-bootcamp-fb5c67579-96t49 1/1 Running 0 18m 172.18.0.5 minikube <none> <none> kubernetes-bootcamp-fb5c67579-jz5vw 1/1 Running 0 11m 172.18.0.9 minikube <none> <none>
六、更新应用
如果新版本的应用镜像已经发布，如何将旧版本的deployment升级呢？
# 查看当前pod的信息，检查使用的应用镜像版本等信息 $ kubectl describe pods ... # 告诉deployment中的kubernetes-bootcamp，需要将镜像替换为指定的其它镜像 $ kubectl set image deployments/kubernetes-bootcamp kubernetes-bootcamp=jocatalin/kubernetes-bootcamp:v2 deployment.apps/kubernetes-bootcamp image updated # 开始替换 $ kubectl get pods NAME READY STATUS RESTARTS AGE kubernetes-bootcamp-7d44784b7c-55vrt 1/1 Running 0 4s kubernetes-bootcamp-7d44784b7c-cftsl 1/1 Running 0 4s kubernetes-bootcamp-7d44784b7c-dhc42 1/1 Running 0 6s kubernetes-bootcamp-7d44784b7c-lg2bd 1/1 Running 0 7s kubernetes-bootcamp-fb5c67579-9bddh 1/1 Terminating 0 5m42s kubernetes-bootcamp-fb5c67579-sfwwh 1/1 Terminating 0 5m42s kubernetes-bootcamp-fb5c67579-sx9kt 1/1 Terminating 0 5m42s kubernetes-bootcamp-fb5c67579-x4n6h 1/1 Terminating 0 5m42s # 替换完成 $ kubectl get pods NAME READY STATUS RESTARTS AGE kubernetes-bootcamp-7d44784b7c-55vrt 1/1 Running 0 5m kubernetes-bootcamp-7d44784b7c-cftsl 1/1 Running 0 5m kubernetes-bootcamp-7d44784b7c-dhc42 1/1 Running 0 5m2s kubernetes-bootcamp-7d44784b7c-lg2bd 1/1 Running 0 5m3s # 查看当前pod的信息，检查使用的应用镜像版本等信息 $ kubectl describe pods ...
如果新版本镜像部署有问题，还可以及时回滚：
# 回滚deployments/kubernetes-bootcamp到上一个版本 $ kubectl rollout undo deployments/kubernetes-bootcamp deployment.apps/kubernetes-bootcamp rolled back # 回滚中 $ kubectl get pods NAME READY STATUS RESTARTS AGE kubernetes-bootcamp-7d44784b7c-55vrt 1/1 Terminating 0 10m kubernetes-bootcamp-7d44784b7c-cftsl 1/1 Terminating 0 10m kubernetes-bootcamp-7d44784b7c-dhc42 1/1 Terminating 0 10m kubernetes-bootcamp-7d44784b7c-lg2bd 1/1 Running 0 10m kubernetes-bootcamp-fb5c67579-6lbbh 0/1 ContainerCreating 0 1s kubernetes-bootcamp-fb5c67579-84hrk 0/1 ContainerCreating 0 1s kubernetes-bootcamp-fb5c67579-n8xnp 1/1 Running 0 4s kubernetes-bootcamp-fb5c67579-qgrs7 1/1 Running 0 4s # 回滚完成 $ kubectl get pods NAME READY STATUS RESTARTS AGE kubernetes-bootcamp-fb5c67579-6lbbh 1/1 Running 0 95s kubernetes-bootcamp-fb5c67579-84hrk 1/1 Running 0 95s kubernetes-bootcamp-fb5c67579-n8xnp 1/1 Running 0 98s kubernetes-bootcamp-fb5c67579-qgrs7 1/1 Running 0 98s # 查看当前pod的信息，检查使用的应用镜像版本等信息 $ kubectl describe pods ...
七、参考文档
https://kubernetes.io/zh-cn/docs/tutorials/kubernetes-basics/
