k8s之yaml文件详解

## 1\. k8s支持的文件格式

Kubernetes支持YAML和JSON格式管理资源对象 JSON格式：主要用于api接口之间消息的传递

YAML格式：用于配置和管理，YAML是一种简洁的非标记性语言，内容格式人性化，较易读

## 2\. YAML语言格式

● 大小写敏感 ● 使用缩进表示层级关系 ● 不支持Tab键制表符缩进，只使用空格缩进 ● 缩进的空格数目不重要，只要相同层级的元素左侧对齐即可，通常开头缩进两个空格 ● 符号字符后缩进一个空格，如冒号，逗号，短横杠（-）等 ● “---”表示YAML格式，一个文件的开始，用于分隔文件

● “#”表示注释

## 3\. 查看api资源版本标签

kubectl api-versions

```
[root@master ~]# kubectl api-versions
admissionregistration.k8s.io/v1beta1
apiextensions.k8s.io/v1beta1
apiregistration.k8s.io/v1
apiregistration.k8s.io/v1beta1
apps/v1
apps/v1beta1
apps/v1beta2
authentication.k8s.io/v1
authentication.k8s.io/v1beta1
authorization.k8s.io/v1
authorization.k8s.io/v1beta1
autoscaling/v1
autoscaling/v2beta1
autoscaling/v2beta2
batch/v1
batch/v1beta1
certificates.k8s.io/v1beta1
coordination.k8s.io/v1
coordination.k8s.io/v1beta1
events.k8s.io/v1beta1
extensions/v1beta1
networking.k8s.io/v1
networking.k8s.io/v1beta1
node.k8s.io/v1beta1
policy/v1beta1
rbac.authorization.k8s.io/v1
rbac.authorization.k8s.io/v1beta1
scheduling.k8s.io/v1
scheduling.k8s.io/v1beta1
storage.k8s.io/v1
storage.k8s.io/v1beta1
v1
```

![](/media/202301/2023-01-13_162532_5758500.017574025970135354.png) 如果是业务场景，一般首选使用apps/v1（apps/v1从v1.9版本开始提供API）。 在k8s v1.16版本之前使用的是extensions/v1beta1，extensions/v1beta1从v1.20版本开始不再提供Ingress资源。

带有beta字样的代表的是测试版本，不用在生产环境中。

## 4\. 编写nginx-test.yaml资源配置清单

### 4.1 编写资源配置清单

```
[root@master ~]# mkdir /opt/test
[root@master ~]# cd !$
cd /opt/test
[root@master test]# vim nginx-test.yaml

#指定api版本标签
apiVersion: apps/v1
#定义资源的类型/角色，deployment为副本控制器
#此处资源类型可以是Deployment、Job、Ingress、Service等
kind: Deployment
#定义资源的元数据信息，比如资源的名称、namespace、标签等信息
metadata:
#定义资源的名称，在同一个namespace空间中必须是唯一的
  name: nginx-test
  lables:
    app: nginx
#定义deployment资源需要的参数属性，诸如是否在容器失败时重新启动容器的属性
spec:
#定义副本数量
  replicas: 3
#定义标签选择器
  selector:
#定义匹配标签
    matchLabels:
#需与后面的.spec.template.metadata.labels定义的标签保持一致
      app: nginx
#定义业务模板，如果有多个副本，所有副本的属性会按照模板的相关配置进行匹配
  template:
    metadata:
#定义Pod副本将使用的标签，需与前面的.spec.selector.matchLabels定义的标签保持一致
      labels:
        app: nginx
    spec:
#定义容器属性
      containers:
#定义一个容器名，一个-name:定义一个容器
      - name: nginx
#定义容器使用的镜像以及版本
        image: nginx:1.15.4
        ports:
#定义容器对外的端口
        - containerPort: 80
```

### 4.2 创建资源对象

kubectl create -f nginx-test.yaml

```
[root@master test]# kubectl create -f nginx-test.yaml 
deployment.apps/nginx-test created
```

### 4.3 查看创建的pod资源

kubectl get pods -o wide

```
[root@master test]# kubectl get pods -o wide
NAME                         READY   STATUS              RESTARTS   AGE   IP       NODE     NOMINATED NODE   READINESS GATES
nginx-test-9b644dcd5-fdvn6   0/1     ContainerCreating   0          4s    <none>   node02   <none>           <none>
nginx-test-9b644dcd5-j6cv7   0/1     ContainerCreating   0          4s    <none>   node01   <none>           <none>
nginx-test-9b644dcd5-pwrt2   0/1     ContainerCreating   0          4s    <none>   node02   <none>           <none>
```

## 5\. 创建service服务对外提供访问并测试

### 5.1 编写nginx-svc-test.yaml

```
[root@master test]# vim nginx-svc-test.yaml

apiVersion: v1
kind: Service
metadata:
  name: nginx-svc
  labels:
    app: nginx
spec:
  type: NodePort
  ports:
  - port: 80
    targetPort: 80
  selector:
#此处定义的selector要与deployment所定义的selector相同
#service依靠标签选择器来检索提供服务的nodes
    app: nginx
```

### 5.2 创建资源对象

kubectl create -f nginx-svc-test.yaml

```
[root@master test]# kubectl create -f nginx-svc-test.yaml
service/nginx-svc created
```

### 5.3 查看创建的service

kubectl get svc

```
[root@master test]# kubectl get svc
NAME         TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)        AGE
kubernetes   ClusterIP   10.1.0.1      <none>        443/TCP        28h
nginx-svc    NodePort    10.1.101.27   <none>        80:32421/TCP   5s
```

### 5.4 访问测试

在浏览器输入nodeIP:nodePort即可访问  
curl 192.168.122.11:32421

```
[root@master test]# curl 192.168.122.11:32421
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    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>
```

curl 192.168.122.12:32421

```
[root@master test]# curl 192.168.122.12:32421
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    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>
```

## 6\. 详解k8s中的port

![](https://img2020.cnblogs.com/blog/2391905/202111/2391905-20211104003018247-1587126719.png) 
● port port是k8s集群内部访问service的端口，即通过clusterIP:port可以从Pod所在的Node上访问到service 
● nodePort nodePort是外部访问k8s集群中service的端口，通过nodeIP:nodePort可以从外部访问到某个service 
● targetPort targetPort是Pod的端口，从port或nodePort来的流量经过kube-proxy反向代理负载均衡转发到后端Pod的targetPort上，最后进入容器。 
● containerPort
containerPort是Pod内部容器的端口，targetPort映射到containerPort。

## 7\. 试运行生成yaml模板后创建实例

### 7.1 --dry-run：试运行

kubectl run --dry-run打印相应的API对象而不执行创建  
kubectl run dryrun-test --image=nginx --port=80 --replicas=3 --dry-run

```
[root@master test]# kubectl run dryrun-test --image=nginx --port=80 --replicas=3 --dry-run
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
deployment.apps/dryrun-test created (dry run)
[root@master test]# kubectl get pod,deploy

No resources found.
```

\--dry-run表示试运行，不真正执行命令（测试命令是否正确），即并不会真的创建出pod和deployment实例，去掉该参数后即可真正执行命令。

### 7.2 查看生成yaml格式

使用--dry-run试运行可不触发生成命令，然后通过-o yaml可实现对其yaml资源配置清单的查看  
kubectl run dryrun-test --image=nginx --port=80 --replicas=3 --dry-run -o yaml

```
[root@master test]# kubectl run dryrun-test --image=nginx --port=80 --replicas=3 --dry-run -o yaml
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    run: dryrun-test
  name: dryrun-test
spec:
  replicas: 3
  selector:
    matchLabels:
      run: dryrun-test
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        run: dryrun-test
    spec:
      containers:
      - image: nginx
        name: dryrun-test
        ports:
        - containerPort: 80
        resources: {}
status: {}
```

### 7.3 查看生成json格式

同理，可通过-o json查看该命令产生的json配置清单  
kubectl run dryrun-test --image=nginx --port=80 --replicas=3 --dry-run -o json

```
[root@master test]# kubectl run dryrun-test --image=nginx --port=80 --replicas=3 --dry-run -o json
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
{
    "kind": "Deployment",
    "apiVersion": "apps/v1",
    "metadata": {
        "name": "dryrun-test",
        "creationTimestamp": null,
        "labels": {
            "run": "dryrun-test"
        }
    },
    "spec": {
        "replicas": 3,
        "selector": {
            "matchLabels": {
                "run": "dryrun-test"
            }
        },
        "template": {
            "metadata": {
                "creationTimestamp": null,
                "labels": {
                    "run": "dryrun-test"
                }
            },
            "spec": {
                "containers": [
                    {
                        "name": "dryrun-test",
                        "image": "nginx",
                        "ports": [
                            {
                                "containerPort": 80
                            }
                        ],
                        "resources": {}
                    }
                ]
            }
        },
        "strategy": {}
    },
    "status": {}
}
```

### 7.4 yaml和json的主要区别

● YAML使用空格缩进，这是Python开发人员熟悉的领域。 ● JavaScript开发人员喜欢JSON，因为它是JavaScript的一个子集，可以直接在JavaScript中解释和编写，同时使用简写方式声明JSON，在使用没有空格的典型变量名时，不需要键中的双引号。 ● 有很多解析器在YAML和JSON的所有语言中都能很好地工作。 ● 在许多情况下，YAML的空白格式可以更容易查看，因为格式化需要更人性化的方法。 ● 如果您的编辑器中没有空格可见或缩进线指示符，那么YAML的空白虽然更紧凑，更容易查看，但可能难以手动编辑。 ● JSON的序列化和反序列化要快得多，因为要检查的功能明显少于YAML，这使得更小更轻的代码能够处理JSON。

● 一个常见的误解是YAML需要较少的标点符号并且比JSON更紧凑，但这完全是错误的。空格是不可见的，所以看起来字符较少，但是如果你计算实际的空格是必要的，以便正确解释YAML以及正确的缩进，你会发现YAML实际上需要比JSON更多的字符。JSON不使用空格来表示层次结构或分组，并且可以通过删除不必要的空格来轻松展平，以实现更紧凑的传输。

### 7.5 使用yaml格式导出生成模板

kubectl run dryrun-test --image=nginx --port=80 --replicas=3 --dry-run -o yaml > dryrun-test.yaml

```
[root@master test]# kubectl run dryrun-test --image=nginx --port=80 --replicas=3 --dry-run -o yaml > dryrun-test.yaml
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
[root@master test]# ls
dryrun-test.yaml  nginx-svc-test.yaml  nginx-test.yaml
```

### 7.6 删除一些不必要的参数

```
[root@master test]# vim dryrun-test.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
#删除下行
  creationTimestamp: null
  labels:
    run: dryrun-test
  name: dryrun-test
spec:
  replicas: 3
  selector:
    matchLabels:
      run: dryrun-test
#删除下行
  strategy: {}
  template:
    metadata:
#删除下行
      creationTimestamp: null
      labels:
        run: dryrun-test
    spec:
      containers:
      - image: nginx
        name: dryrun-test
        ports:
        - containerPort: 80
#删除下行
        resources: {}
#删除下行
status: {}
```

### 7.7 使用yaml模板创建实例

kubectl apply -f dryrun-test.yaml

```
[root@master test]# kubectl apply -f dryrun-test.yaml 
deployment.apps/dryrun-test created
[root@master test]# kubectl get pod,deploy
NAME                               READY   STATUS    RESTARTS   AGE
pod/dryrun-test-6c4ddc89bd-25lcm   1/1     Running   0          39s
pod/dryrun-test-6c4ddc89bd-bbsnm   1/1     Running   0          39s
pod/dryrun-test-6c4ddc89bd-rnmjk   1/1     Running   0          39s

NAME                                READY   UP-TO-DATE   AVAILABLE   AGE
deployment.extensions/dryrun-test   3/3     3            3           39s
```

## 8\. 将现有资源生成yaml模板导出并保存为文件

### 8.1 --expose：查看现有资源的yaml配置清单

kubectl get deploy dryrun-test --export -o yaml

```
[root@master test]# kubectl get deploy dryrun-test --export -o yaml
Flag --export has been deprecated, This flag is deprecated and will be removed in future.
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  annotations:
    deployment.kubernetes.io/revision: "1"
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"labels":{"run":"dryrun-test"},"name":"dryrun-test","namespace":"default"},"spec":{"replicas":3,"selector":{"matchLabels":{"run":"dryrun-test"}},"template":{"metadata":{"labels":{"run":"dryrun-test"}},"spec":{"containers":[{"image":"nginx","name":"dryrun-test","ports":[{"containerPort":80}]}]}}}}
  creationTimestamp: null
  generation: 1
  labels:
    run: dryrun-test
  name: dryrun-test
  selfLink: /apis/extensions/v1beta1/namespaces/default/deployments/dryrun-test
spec:
  progressDeadlineSeconds: 600
  replicas: 3
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      run: dryrun-test
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      creationTimestamp: null
      labels:
        run: dryrun-test
    spec:
      containers:
      - image: nginx
        imagePullPolicy: Always
        name: dryrun-test
        ports:
        - containerPort: 80
          protocol: TCP
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
status: {}
```

### 8.2 保存到文件中

kubectl get deploy dryrun-test --export -o yaml > export-test.yaml

```
[root@master test]# kubectl get deploy dryrun-test --export -o yaml > export-test.yaml
Flag --export has been deprecated, This flag is deprecated and will be removed in future.
[root@master test]# ls
dryrun-test.yaml  export-test.yaml  nginx-svc-test.yaml  nginx-test.yaml
```

## 9\. explain：查看字段帮助信息

可一层层的查看相关资源对象的帮助信息  
kubectl explain deployments.spec.template.spec.containers

```
[root@master test]# kubectl explain deployments.spec.template.spec.containers
KIND:     Deployment
VERSION:  extensions/v1beta1

RESOURCE: containers <[]Object>

DESCRIPTION:
     List of containers belonging to the pod. Containers cannot currently be
     added or removed. There must be at least one container in a Pod. Cannot be
     updated.

A single application container that you want to run within a pod.

FIELDS:
   args	<[]string>
     Arguments to the entrypoint. The docker image's CMD is used if this is not
     provided. Variable references $(VAR_NAME) are expanded using the
     container's environment. If a variable cannot be resolved, the reference in
     the input string will be unchanged. The $(VAR_NAME) syntax can be escaped
     with a double $$, ie: $$(VAR_NAME). Escaped references will never be
     expanded, regardless of whether the variable exists or not. Cannot be
     updated. More info:
     https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/#running-a-command-in-a-shell
......
```

kubectl explain pods.spec.containers

```
[root@master test]# kubectl explain pods.spec.containers
KIND:     Pod
VERSION:  v1

RESOURCE: containers <[]Object>

DESCRIPTION:
     List of containers belonging to the pod. Containers cannot currently be
     added or removed. There must be at least one container in a Pod. Cannot be
     updated.

A single application container that you want to run within a pod.

FIELDS:
   args	<[]string>
     Arguments to the entrypoint. The docker image's CMD is used if this is not
     provided. Variable references $(VAR_NAME) are expanded using the
     container's environment. If a variable cannot be resolved, the reference in
     the input string will be unchanged. The $(VAR_NAME) syntax can be escaped
     with a double $$, ie: $$(VAR_NAME). Escaped references will never be
     expanded, regardless of whether the variable exists or not. Cannot be
     updated. More info:
     https://kubernetes.io/docs/tasks/inject-data-application/define-command-argument-container/#running-a-command-in-a-shell
......
```

## 10\. 获取资源配置清单的总结

● 没有相关资源，使用run命令--dry-run选项 kubectl run dryrun-test --image=nginx --port=80 --replicas=3 --dry-run -o yaml > dryrun-test.yaml ● 已有相关资源，使用get命令--export选项

kubectl get deploy dryrun-test --export -o yaml > export-test.yaml