k8s之yaml文件详解
目录
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
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
● 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*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