【k8s 实操（二）】部署应用

【k8s 实操（二）】部署应用

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.Info{Major:"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.Info{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"}

运行 kubectl get nodes 命令以查看集群中的节点：

NAME STATUS ROLES AGE VERSIONminikube 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:v1deployment.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 AGEkubernetes-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 "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 "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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