k8s 入门实战

一、 Namespace

Namespace是kubernetes系统中的一种非常重要资源，它的主要作用是用来实现多套环境的资源隔离或者多租户的资源隔离。

默认情况下，kubernetes集群中的所有的Pod都是可以相互访问的。但是在实际中，可能不想让两个Pod之间进行互相的访问，那此时就可以将两个Pod划分到不同的namespace下。kubernetes通过将集群内部的资源分配到不同的Namespace中，可以形成逻辑上的"组"，以方便不同的组的资源进行隔离使用和管理。

可以通过kubernetes的授权机制，将不同的namespace交给不同租户进行管理，这样就实现了多租户的资源隔离。此时还能结合kubernetes的资源配额机制，限定不同租户能占用的资源，例如CPU使用量、内存使用量等等，来实现租户可用资源的管理。

kubernetes在集群启动之后，会默认创建几个namespace

[root@master ~]# kubectl get namespace
NAME              STATUS   AGE
default           Active   46h			#  所有未指定Namespace的对象都会被分配在default命名空间
kube-node-lease   Active   46h			 #  集群节点之间的心跳维护，v1.13开始引入
kube-public       Active   46h			#  此命名空间下的资源可以被所有人访问（包括未认证用户）
kube-system       Active   46h			#  所有由Kubernetes系统创建的资源都处于这个命名空间

下面来看namespace资源的具体操作：

查看

[root@master ~]# kubectl get ns 
NAME              STATUS   AGE
default           Active   46h
kube-node-lease   Active   46h
kube-public       Active   46h
kube-system       Active   46h
# 2 查看指定的ns   命令：kubectl get ns ns名称

[root@master ~]# kubectl get ns default
NAME      STATUS   AGE
default   Active   46h

# 3 指定输出格式  命令：kubectl get ns ns名称  -o 格式参数# kubernetes支持的格式有很多，比较常见的是wide、json、yaml
[root@master ~]# kubectl get ns default -o yaml 
apiVersion: v1
kind: Namespace
metadata:
  creationTimestamp: "2025-10-28T08:25:07Z"
  labels:
    kubernetes.io/metadata.name: default
  name: default
  resourceVersion: "43"
  uid: f8b72930-4068-4495-8a8c-e3c5b73350b0
spec:
  finalizers:
  - kubernetes
status:
  phase: Active
[root@master ~]# kubectl describe ns default
Name:         default
Labels:       kubernetes.io/metadata.name=default
Annotations:  <none>
Status:       Active

No resource quota.

No LimitRange resource.

  # 4 查看ns详情  命令：kubectl describe ns ns名称
[root@master ~]# kubectl describe ns default 
Name:         default
Labels:       kubernetes.io/metadata.name=default
Annotations:  <none>
Status:       Active

No resource quota.

No LimitRange resource.

创建

[root@master ~]# kubectl create ns dev
namespace/dev created

删除

[root@master ~]# kubectl delete ns dev
namespace "dev" deleted

配置方式

[root@master ~]# kubectl apply -f dev.yaml 
namespace/dev created
[root@master ~]# kubectl get ns 
NAME              STATUS   AGE
default           Active   46h
dev               Active   26s
kube-node-lease   Active   46h
kube-public       Active   46h
kube-system       Active   46h

然后就可以执行对应的创建和删除命令了：

创建：kubectl create -f ns-dev.yaml

删除：kubectl delete -f ns-dev.yaml

二、 Pod

Pod是kubernetes集群进行管理的最小单元，程序要运行必须部署在容器中，而容器必须存在于Pod中。

Pod可以认为是容器的封装，一个Pod中可以存在一个或者多个容器。

kubernetes在集群启动之后，集群中的各个组件也都是以Pod方式运行的。可以通过下面命令查看：

[root@master ~]# kubectl get pod -n kube-system
NAME                                      READY   STATUS    RESTARTS      AGE
calico-kube-controllers-9d57d8f49-gchdn   1/1     Running   3 (35m ago)   46h
calico-node-rwcj2                         1/1     Running   3 (35m ago)   46h
calico-node-wtl66                         1/1     Running   3 (35m ago)   46h
calico-node-zvf2b                         1/1     Running   4 (35m ago)   46h
coredns-6554b8b87f-4nhjv                  1/1     Running   3 (35m ago)   46h
coredns-6554b8b87f-jx88p                  1/1     Running   3 (35m ago)   46h
etcd-master                               1/1     Running   4 (35m ago)   46h
kube-apiserver-master                     1/1     Running   5 (34m ago)   46h
kube-controller-manager-master            1/1     Running   4 (35m ago)   46h
kube-proxy-6dz89                          1/1     Running   3 (35m ago)   46h
kube-proxy-7wvvg                          1/1     Running   4 (35m ago)   46h
kube-proxy-knrwh                          1/1     Running   3 (35m ago)   46h
kube-scheduler-master                     1/1     Running   4 (35m ago)   46h

创建并运行

kubernetes没有提供单独运行Pod的命令，都是通过Pod控制器来实现的

[root@master ~]# kubectl run nginxpod --image=nginx:latest --port=80 -n dev 
pod/nginxpod created

查看pod信息

[root@master ~]# kubectl get pods -n dev
NAME       READY   STATUS    RESTARTS   AGE
nginxpod   1/1     Running   0          17s
# 查看Pod的详细信息
[root@master ~]# kubectl describe pod nginxpod -n dev
Name:             nginxpod
Namespace:        dev
Priority:         0
Service Account:  default
Node:             node2/192.168.110.33
Start Time:       Thu, 30 Oct 2025 14:37:16 +0800
Labels:           run=nginxpod
Annotations:      cni.projectcalico.org/containerID: f9c7bd2ed90f5151b4a8bc8bd4bbd3eb8ec4a6546b82db48867891dae761c69f
                  cni.projectcalico.org/podIP: 172.16.104.9/32
                  cni.projectcalico.org/podIPs: 172.16.104.9/32
Status:           Running
IP:               172.16.104.9
IPs:
  IP:  172.16.104.9
Containers:
  nginxpod:
    Container ID:   docker://020881faea15fac4cf20c1b4034ae5cfdf749c0d4a955861a17f2ecc1047ce0c
    Image:          nginx:latest
    Image ID:       docker-pullable://nginx@sha256:0511d915d4e7467a27e8eecd90643dbb60e148c0ef3b7486655296f8c768cadc
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Thu, 30 Oct 2025 14:37:18 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-lmsmw (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  kube-api-access-lmsmw:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    ConfigMapOptional:       <nil>
    DownwardAPI:             true
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  54s   default-scheduler  Successfully assigned dev/nginxpod to node2
  Normal  Pulling    53s   kubelet            Pulling image "nginx:latest"
  Normal  Pulled     52s   kubelet            Successfully pulled image "nginx:latest" in 962ms (962ms including waiting)
  Normal  Created    52s   kubelet            Created container nginxpod
  Normal  Started    52s   kubelet            Started container nginxpod

访问Pod

[root@master ~]# kubectl get pods -n dev -o wide
NAME       READY   STATUS    RESTARTS   AGE     IP             NODE    NOMINATED NODE   READINESS GATES
nginxpod   1/1     Running   0          2m10s   172.16.104.9   node2   <none>           <none>
#访问POD
[root@node1 ~]# curl http://172.16.104.9:80
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>

<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>

<p><em>Thank you for using nginx.</em></p>
</body>
</html>

删除指定Pod

[root@master ~]# kubectl delete pod nginxpod -n dev
pod "nginxpod" deleted

//当前pod是由pod控制器管理

[root@master ~]# kubectl create deployment nginxpod --image=nginx:latest --port=80 -n dev 
deployment.apps/nginxpod created
[root@master ~]# kubectl get pods -n dev
NAME                        READY   STATUS    RESTARTS   AGE
nginxpod-556785b5bb-xl76s   1/1     Running   0          16s
[root@master ~]# kubectl get deploy -n dev
NAME       READY   UP-TO-DATE   AVAILABLE   AGE
nginxpod   1/1     1            1           88s

接下来，删除此PodPod控制器

[root@master ~]# kubectl delete deploy nginxpod -n dev 
deployment.apps "nginxpod" deleted

配置操作

[root@master ~]# cat nginxpod.yaml 
apiVersion: v1
kind: Namespace
metadata:
  name: dev
---
apiVersion: v1
kind: Pod
metadata:
  name: nginx
  namespace: dev
spec:
  containers:
  - name: nginx
    image: nginx:1.14.2
    ports:
    - containerPort: 80
[root@master ~]# kubectl apply -f nginxpod.yaml 
namespace/dev unchanged
pod/nginx created
[root@master ~]# kubectl delete -f nginxpod.yaml 
namespace "dev" deleted
pod "nginx" deleted

三、 Label

Label是kubernetes系统中的一个重要概念。它的作用就是在资源上添加标识，用来对它们进行区分和选择。

Label的特点：

• 一个Label会以key/value键值对的形式附加到各种对象上，如Node、Pod、Service等等
• 一个资源对象可以定义任意数量的Label ，同一个Label也可以被添加到任意数量的资源对象上去
• Label通常在资源对象定义时确定，当然也可以在对象创建后动态添加或者删除

可以通过Label实现资源的多维度分组，以便灵活、方便地进行资源分配、调度、配置、部署等管理工作。

一些常用的Label 示例如下：

· 版本标签：“version”:“release”, “version”:“stable”…

· 环境标签：“environment”:“dev”，“environment”:“test”，“environment”:“pro”

· 架构标签：“tier”:“frontend”，“tier”:“backend”

标签定义完毕之后，还要考虑到标签的选择，这就要使用到Label Selector，即：

Label用于给某个资源对象定义标识

Label Selector用于查询和筛选拥有某些标签的资源对象

当前有两种Label Selector：

基于等式的Label Selector

name = slave: 选择所有包含Label中key="name"且value="slave"的对象

env != production: 选择所有包括Label中的key="env"且value不等于"production"的对象

基于集合的Label Selector

name in (master, slave): 选择所有包含Label中的key="name"且value="master"或"slave"的对象

name not in (frontend): 选择所有包含Label中的key="name"且value不等于"frontend"的对象

标签的选择条件可以使用多个，此时将多个Label Selector进行组合，使用逗号","进行分隔即可。例如：

name=slave，env!=production

name not in (frontend)，env!=production

命令方式

# 为pod资源打标签
[root@master ~]# kubectl label pod nginx aa=cc -n dev
pod/nginx labeled
# 查看标签、
[root@master ~]# kubectl get pod nginx -n dev --show-labels
NAME    READY   STATUS    RESTARTS   AGE     LABELS
nginx   1/1     Running   0          6m42s   aa=cc,run=nginx
# 筛选标签
[root@master ~]# kubectl get pod -n dev -l aa=cc  --show-labels
NAME    READY   STATUS    RESTARTS   AGE   LABELS
nginx   1/1     Running   0          84m   aa=cc,run=nginx,teat=aa
# 删除标签
[root@master ~]# kubectl label pod nginx aa- -n dev
pod/nginx unlabeled
[root@master ~]# kubectl get pod nginx -n dev --show-labels
NAME    READY   STATUS    RESTARTS   AGE   LABELS
nginx   1/1     Running   0          86m   run=nginx,teat=aa

配置方式

[root@master ~]# cat nginxpod.yaml 
apiVersion: v1
kind: Namespace
metadata:
  name: dev
---
apiVersion: v1
kind: Pod
metadata:
  name: nginx1
  namespace: dev
  labels:
    lq: ws
spec:
  containers:
  - name: nginx
    image: nginx:1.14.2
    ports:
    - containerPort: 80
[root@master ~]# kubectl apply -f nginxpod.yaml
[root@master ~]# kubectl get pod nginx1 -n dev --show-labels
NAME     READY   STATUS    RESTARTS   AGE   LABELS
nginx1   1/1     Running   0          87s   lq=ws

四、 Deployment

在kubernetes中，Pod是最小的控制单元，但是kubernetes很少直接控制Pod，一般都是通过Pod控制器来完成的。Pod控制器用于pod的管理，确保pod资源符合预期的状态，当pod的资源出现故障时，会尝试进行重启或重建pod。

在kubernetes中Pod控制器的种类有很多，本章节只介绍一种：Deployment。

命令操作

# 命令格式: kubectl create deployment 名称  [参数] 
# --image  指定pod的镜像
# --port   指定端口
# --replicas  指定创建pod数量
# --namespace  指定namespace

[root@master ~]# kubectl create deploy nginx --image=nginx:latest --port=80 --replicas=3 -n dev
deployment.apps/nginx created
[root@master ~]# kubectl get deploy 
# 查看创建的Pod
[root@master ~]# kubectl get pods -n dev
NAME                     READY   STATUS    RESTARTS   AGE
nginx-7c79c4bf97-lt5mh   1/1     Running   0          74s
nginx-7c79c4bf97-x8gnh   1/1     Running   0          74s
nginx-7c79c4bf97-x98gg   1/1     Running   0          74s

# 查看deployment的信息
[root@master ~]# kubectl get deploy -n dev
NAME    READY   UP-TO-DATE   AVAILABLE   AGE
nginx   3/3     3            3           23s

[root@master ~]# kubectl get deploy -n dev -o wide
NAME    READY   UP-TO-DATE   AVAILABLE   AGE    CONTAINERS   IMAGES         SELECTOR
nginx   3/3     3            3           112s   nginx        nginx:latest   app=nginx

# 查看deployment的详细信息
[root@master ~]# kubectl describe deploy nginx -n dev
Name:                   nginx
Namespace:              dev
CreationTimestamp:      Thu, 30 Oct 2025 18:32:46 +0800
Labels:                 app=nginx
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               app=nginx
Replicas:               3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=nginx
  Containers:
   nginx:
    Image:        nginx:latest
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   nginx-7c79c4bf97 (3/3 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  3m10s  deployment-controller  Scaled up replica set nginx-7c79c4bf97 to 3

# 删除 
[root@master ~]# kubectl delete deploy nginx -n dev
deployment.apps "nginx" deleted

配置操作

[root@master ~]# cat deploy.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
  namespace: dev
spec:
  replicas: 4
  selector:
    matchLabels:
      run: nginx
  template:
    metadata:
      labels:
        run: nginx
    spec:
      containers:
      - image: nginx:latest
        name: nginx
        ports:
        - containerPort: 80
          protocol: TCP

[root@master ~]# kubectl apply -f deploy.yaml 
deployment.apps/nginx created
[root@master ~]# kubectl get pods -n dev 
NAME                     READY   STATUS    RESTARTS   AGE
nginx-6c45cbd8c5-2nsr4   1/1     Running   0          27s
nginx-6c45cbd8c5-hqtgp   1/1     Running   0          27s
nginx-6c45cbd8c5-kkbd8   1/1     Running   0          27s
nginx-6c45cbd8c5-tm4zw   1/1     Running   0          27s
[root@master ~]# kubectl delete -f deploy.yaml 
deployment.apps "nginx" deleted