k8s 实操部署应用

Posted 2022-02-14 看，未来

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文章目录

- 使用 kubectl 创建 Deployment

使用 kubectl 创建 Deployment

前边咱搭建了集群环境，现在咱来部署一下应用，不然集群搭建来干嘛？

为此，我们需要先创建 Kubernetes Deployment 配置。Deployment 指挥 Kubernetes 如何创建和更新应用程序的实例。创建 Deployment 后，Kubernetes master 将应用程序实例调度到集群中的各个节点上。

创建应用程序实例后，Kubernetes Deployment 控制器会持续监视这些实例。如果托管实例的节点关闭或被删除，则 Deployment 控制器会将该实例替换为群集中另一个节点上的实例。这提供了一种自我修复机制来解决机器故障维护问题。

在没有 Kubernetes 这种编排系统之前，安装脚本通常用于启动应用程序，但它们不允许从机器故障中恢复。通过创建应用程序实例并使它们在节点之间运行， Kubernetes Deployments 提供了一种与众不同的应用程序管理方法。

kubectl命令的常见格式是：kubectl action resource。这将对指定的资源（如节点、容器）执行指定的操作（如创建、描述）。可以在命令之后使用–help来获取有关可能参数的其他信息。

通过运行kubectl version命令，检查kubectl是否已安装：

Client Version: version.InfoMajor:"1", Minor:"20", GitVersion:"v1.20.4", GitCommit:"e87da0bd6e03ec3fea7933c4b5263d151aafd07c", GitTreeState:"clean", BuildDate:"2021-02-18T16:12:00Z", GoVersion:"go1.15.8", Compiler:"gc", Platform:"linux/amd64"
Server Version: version.InfoMajor:"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"

运行 kubectl get nodes 命令以查看集群中的节点：

NAME       STATUS   ROLES                  AGE   VERSION
minikube   Ready    control-plane,master   15m   v1.20.2

依旧是那倔强且孤单的一个节点哈。

Kubernetes将根据节点可用资源选择在何处部署我们的应用程序。

使用 kubectl create deployment 命令在 Kubernetes 上部署我们的第一个应用程序。我们需要提供部署名称和应用程序映像位置（包括Docker hub外部托管映像的完整存储库url）。

kubectl create deployment kubernetes-bootcamp --image=gcr.io/google-samples/kubernetes-bootcamp:v1

kubectl create deployment kubernetes-bootcamp --image=gcr.io/google-samples/kubernetes-bootcamp:v1
deployment.apps/kubernetes-bootcamp created

好了。
要列出以部署的应用可以：kubectl get deployments

NAME                  READY   UP-TO-DATE   AVAILABLE   AGE
kubernetes-bootcamp   1/1     1            1           2m3s

Kubernetes 内部运行的 Pod 运行在一个独立的专用网络上。默认情况下，它们在同一 kubernetes 集群内的其他 POD 和服务中可见，但在该网络之外不可见。当我们使用 kubectl 时，我们通过 API 端点与应用程序进行交互。

kubectl命令可以创建一个代理，将通信转发到集群范围的专用网络。可以通过按 control-C 终止代理，并且在代理运行时不会显示任何输出。

kubectl proxy

Starting to serve on 127.0.0.1:8001

现在，我们的主机（在线终端）和Kubernetes集群之间有了连接。代理允许从这些终端直接访问API。

看到通过代理端点托管的所有API。例如，我们可以使用curl命令直接通过API查询版本：

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"

API服务器将根据pod名称自动为每个pod创建一个端点，该端点也可以通过代理访问。

首先，我们需要获取Pod名称，并将其存储在环境变量Pod_name中：

export POD_NAME=$(kubectl get pods -o go-template --template 'range .items.metadata.name"\\n"end')
echo Name of the Pod: $POD_NAME

接下来可以通过下面的 IP 访问 Pod:

curl http://localhost:8001/api/v1/namespaces/default/pods/$POD_NAME/


  "kind": "Pod",
  "apiVersion": "v1",
  "metadata": 
    "name": "kubernetes-bootcamp-57978f5f5d-clzbr",
    "generateName": "kubernetes-bootcamp-57978f5f5d-",
    "namespace": "default",
    "uid": "d28f7fbe-73be-4917-ae6c-9e1e77eb25e2",
    "resourceVersion": "1292",
    "creationTimestamp": "2022-01-28T08:24:01Z",
    "labels": 
      "app": "kubernetes-bootcamp",
      "pod-template-hash": "57978f5f5d"
    ,
    "ownerReferences": [
      
        "apiVersion": "apps/v1",
        "kind": "ReplicaSet",
        "name": "kubernetes-bootcamp-57978f5f5d",
        "uid": "24323ea4-7b0c-4a09-9d0e-749f15c2052f",
        "controller": true,
        "blockOwnerDeletion": true
      
    ],
    "managedFields": [
      
        "manager": "kube-controller-manager",
        "operation": "Update",
        "apiVersion": "v1",
        "time": "2022-01-28T08:24:01Z",
        "fieldsType": "FieldsV1",
        "fieldsV1": "f:metadata":"f:generateName":,"f:labels":".":,"f:app":,"f:pod-template-hash":,"f:ownerReferences":".":,"k:\\"uid\\":\\"24323ea4-7b0c-4a09-9d0e-749f15c2052f\\"":".":,"f:apiVersion":,"f:blockOwnerDeletion":,"f:controller":,"f:kind":,"f:name":,"f:uid":,"f:spec":"f:containers":"k:\\"name\\":\\"kubernetes-bootcamp\\"":".":,"f:image":,"f:imagePullPolicy":,"f:name":,"f:resources":,"f:terminationMessagePath":,"f:terminationMessagePolicy":,"f:dnsPolicy":,"f:enableServiceLinks":,"f:restartPolicy":,"f:schedulerName":,"f:securityContext":,"f:terminationGracePeriodSeconds":
      ,
      
        "manager": "kubelet",
        "operation": "Update",
        "apiVersion": "v1",
        "time": "2022-01-28T08:24:03Z",
        "fieldsType": "FieldsV1",
        "fieldsV1": "f:status":"f:conditions":"k:\\"type\\":\\"ContainersReady\\"":".":,"f:lastProbeTime":,"f:lastTransitionTime":,"f:status":,"f:type":,"k:\\"type\\":\\"Initialized\\"":".":,"f:lastProbeTime":,"f:lastTransitionTime":,"f:status":,"f:type":,"k:\\"type\\":\\"Ready\\"":".":,"f:lastProbeTime":,"f:lastTransitionTime":,"f:status":,"f:type":,"f:containerStatuses":,"f:hostIP":,"f:phase":,"f:podIP":,"f:podIPs":".":,"k:\\"ip\\":\\"172.18.0.6\\"":".":,"f:ip":,"f:startTime":
      
    ]
  ,
  "spec": 
    "volumes": [
      
        "name": "default-token-vwk4j",
        "secret": 
          "secretName": "default-token-vwk4j",
          "defaultMode": 420
        
      
    ],
    "containers": [
      
        "name": "kubernetes-bootcamp",
        "image": "gcr.io/google-samples/kubernetes-bootcamp:v1",
        "resources": 
          
        ,
        "volumeMounts": [
          
            "name": "default-token-vwk4j",
            "readOnly": true,
            "mountPath": "/var/run/secrets/kubernetes.io/serviceaccount"
          
        ],
        "terminationMessagePath": "/dev/termination-log",
        "terminationMessagePolicy": "File",
        "imagePullPolicy": "IfNotPresent"
      
    ],
    "restartPolicy": "Always",
    "terminationGracePeriodSeconds": 30,
    "dnsPolicy": "ClusterFirst",
    "serviceAccountName": "default",
    "serviceAccount": "default",
    "nodeName": "minikube",
    "securityContext": 
      
    ,
    "schedulerName": "default-scheduler",
    "tolerations": [
      
        "key": "node.kubernetes.io/not-ready",
        "operator": "Exists",
        "effect": "NoExecute",
        "tolerationSeconds": 300
      ,
      
        "key": "node.kubernetes.io/unreachable",
        "operator": "Exists",
        "effect": "NoExecute",
        "tolerationSeconds": 300
      
    ],
    "priority": 0,
    "enableServiceLinks": true,
    "preemptionPolicy": "PreemptLowerPriority"
  ,
  "status": 
    "phase": "Running",
    "conditions": [
      
        "type": "Initialized",
        "status": "True",
        "lastProbeTime": null,
        "lastTransitionTime": "2022-01-28T08:24:01Z"
      ,
      
        "type": "Ready",
        "status": "True",
        "lastProbeTime": null,
        "lastTransitionTime": "2022-01-28T08:24:03Z"
      ,
      
        "type": "ContainersReady",
        "status": "True",
        "lastProbeTime": null,
        "lastTransitionTime": "2022-01-28T08:24:03Z"
      ,
      
        "type": "PodScheduled",
        "status": "True",
        "lastProbeTime": null,
        "lastTransitionTime": "2022-01-28T08:24:01Z"
      
    ],
    "hostIP": "172.17.0.66",
    "podIP": "172.18.0.6",
    "podIPs": [
      
        "ip": "172.18.0.6"
      
    ],
    "startTime": "2022-01-28T08:24:01Z",
    "containerStatuses": [
      
        "name": "kubernetes-bootcamp",
        "state": 
          "running": 
            "startedAt": "2022-01-28T08:24:03Z"
          
        ,
        "lastState": 
          
        ,
        "ready": true,
        "restartCount": 0,
        "image": "jocatalin/kubernetes-bootcamp:v1",
        "imageID": "docker-pullable://jocatalin/kubernetes-bootcamp@sha256:0d6b8ee63bb57c5f5b6156f446b3bc3b3c143d233037f3a2f00e279c8fcc64af",
        "containerID": "docker://5d812609bb54a4185efd69361084d6f9fa0cffa890d9f821410337b4941f5054",
        "started": true
      
    ],
    "qosClass": "BestEffort"

为了在不使用代理的情况下访问新部署，需要一个服务，后面再说。

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