k8s-YAML配置文件
一、YAML基础
YAML是专门用来写配置文件的语言,非常简洁和强大,使用比json更方便。它实质上是一种通用的数据串行化格式。
YAML语法规则:
- 大小写敏感
- 使用缩进表示层级关系
- 缩进时不允许使用Tal键,只允许使用空格
- 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
- ”#” 表示注释,从这个字符一直到行尾,都会被解析器忽略
在Kubernetes中,只需要知道两种结构类型即可:
- Lists
- Maps
1.1 YAML Maps
Map顾名思义指的是字典,即一个Key:Value 的键值对信息。例如:
--- apiVersion: v1 kind: Pod
注:---为可选的分隔符 ,当需要在一个文件中定义多个结构的时候需要使用。上述内容表示有两个键apiVersion和kind,分别对应的值为v1和Pod。
Maps的value既能够对应字符串也能够对应一个Maps。例如:
--- apiVersion: v1 kind: Pod metadata: name: kube100-site labels: app: web
注:上述的YAML文件中,metadata这个KEY对应的值为一个Maps,而嵌套的labels这个KEY的值又是一个Map。实际使用中可视情况进行多层嵌套。
YAML处理器根据行缩进来知道内容之间的关联。上述例子中,使用两个空格作为缩进,但空格的数据量并不重要,只是至少要求一个空格并且所有缩进保持一致的空格数 。例如,name和labels是相同缩进级别,因此YAML处理器知道他们属于同一map;它知道app是lables的值因为app的缩进更大。
注意:在YAML文件中绝对不要使用tab键
1.2 YAML Lists
List即列表,说白了就是数组,例如:
args -beijing -shanghai -shenzhen -guangzhou
可以指定任何数量的项在列表中,每个项的定义以破折号(-)开头,并且与父元素之间存在缩进。在JSON格式中,表示如下:
{ "args": ["beijing", "shanghai", "shenzhen", "guangzhou"] }
当然Lists的子项也可以是Maps,Maps的子项也可以是List,例如:
--- apiVersion: v1 kind: Pod metadata: name: kube100-site labels: app: web spec: containers: - name: front-end image: nginx ports: - containerPort: 80 - name: flaskapp-demo image: jcdemo/flaskapp ports: 8080
如上述文件所示,定义一个containers的List对象,每个子项都由name、image、ports组成,每个ports都有一个KEY为containerPort的Map组成,转成JSON格式文件:
{ "apiVersion": "v1", "kind": "Pod", "metadata": { "name": "kube100-site", "labels": { "app": "web" }, }, "spec": { "containers": [{ "name": "front-end", "image": "nginx", "ports": [{ "containerPort": "80" }] }, { "name": "flaskapp-demo", "image": "jcdemo/flaskapp", "ports": [{ "containerPort": "5000" }] }] } }
二、说明
- 定义配置时,指定最新稳定版API
- 配置文件应该存储在集群之外的版本控制仓库中。如果需要,可以快速回滚配置、重新创建和恢复
- 应该使用YAML格式编写配置文件,而不是json。YAML对用户更加友好
- 可以将相关对象组合成单个文件,通常会更容易管理
- 不要没必要指定默认值,简单和最小配置减小错误
- 在注释中说明一个对象描述更好维护
三、使用YAML创建Pod
--- apiVersion: v1 kind: Pod metadata: name: kube100-site labels: app: web spec: containers: - name: front-end image: nginx ports: - containerPort: 80 - name: flaskapp-demo image: jcdemo/flaskapp ports: - containerPort: 5000
- apiVersion:此处值是v1,这个版本号需要根据安装的Kubernetes版本和资源类型进行变化,记住不是写死的。
- kind:此处创建的是Pod,根据实际情况,此处资源类型可以是Deployment、Job、Ingress、Service等。
- metadata:包含Pod的一些meta信息,比如名称、namespace、标签等信息。
- spe:包括一些container,storage,volume以及其他Kubernetes需要的参数,以及诸如是否在容器失败时重新启动容器的属性。可在特定Kubernetes API找到完整的Kubernetes Pod的属性。
(1)查看apiVersion
# 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 batch/v1 batch/v1beta1 certificates.k8s.io/v1beta1 events.k8s.io/v1beta1 extensions/v1beta1 networking.k8s.io/v1 policy/v1beta1 rbac.authorization.k8s.io/v1 rbac.authorization.k8s.io/v1beta1 storage.k8s.io/v1 storage.k8s.io/v1beta1 v1
(2)下面是一个典型的容器定义:
… spec: containers: - name: front-end image: nginx ports: - containerPort: 80 …
-
上述例子只是一个简单的最小定义:一个名字(front-end)、基于nginx的镜像,以及容器将会监听的指定端口号(80)。
-
除了上述的基本属性外,还能够指定复杂的属性,包括容器启动运行的命令、使用的参数、工作目录以及每次实例化是否拉取新的副本。 还可以指定更深入的信息,例如容器的退出日志的位置。容器可选的设置属性包括:
name、image、command、args、workingDir、ports、env、resource、volumeMounts、livenessProbe、readinessProbe、livecycle、terminationMessagePath、imagePullPolicy、securityContext、stdin、stdinOnce、tty
(3)kubectl创建Pod
# kubectl create -f test_pod.yaml pod "kube100-site" created
(4)查看Pod状态
# kubectl get pod NAME READY STATUS RESTARTS AGE kube100-site 2/2 Running 0 2m
四、创建Deployment
名词解释
#test-pod apiVersion: v1 #指定api版本,此值必须在kubectl apiversion中 kind: Pod #指定创建资源的角色/类型 metadata: #资源的元数据/属性 name: test-pod #资源的名字,在同一个namespace中必须唯一 labels: #设定资源的标签 k8s-app: apache version: v1 kubernetes.io/cluster-service: "true" annotations: #自定义注解列表 - name: String #自定义注解名字 spec: #specification of the resource content 指定该资源的内容 restartPolicy: Always #表明该容器一直运行,默认k8s的策略,在此容器退出后,会立即创建一个相同的容器 nodeSelector: #节点选择,先给主机打标签kubectl label nodes kube-node1 zone=node1 zone: node1 containers: - name: test-pod #容器的名字 image: 10.192.21.18:5000/test/chat:latest #容器使用的镜像地址 imagePullPolicy: Never #三个选择Always、Never、IfNotPresent,每次启动时检查和更新(从registery)images的策略, # Always,每次都检查 # Never,每次都不检查(不管本地是否有) # IfNotPresent,如果本地有就不检查,如果没有就拉取 command: ['sh'] #启动容器的运行命令,将覆盖容器中的Entrypoint,对应Dockefile中的ENTRYPOINT args: ["$(str)"] #启动容器的命令参数,对应Dockerfile中CMD参数 env: #指定容器中的环境变量 - name: str #变量的名字 value: "/etc/run.sh" #变量的值 resources: #资源管理 requests: #容器运行时,最低资源需求,也就是说最少需要多少资源容器才能正常运行 cpu: 0.1 #CPU资源(核数),两种方式,浮点数或者是整数+m,0.1=100m,最少值为0.001核(1m) memory: 32Mi #内存使用量 limits: #资源限制 cpu: 0.5 memory: 1000Mi ports: - containerPort: 80 #容器开发对外的端口 name: httpd #名称 protocol: TCP livenessProbe: #pod内容器健康检查的设置 httpGet: #通过httpget检查健康,返回200-399之间,则认为容器正常 path: / #URI地址 port: 80 #host: 127.0.0.1 #主机地址 scheme: HTTP initialDelaySeconds: 180 #表明第一次检测在容器启动后多长时间后开始 timeoutSeconds: 5 #检测的超时时间 periodSeconds: 15 #检查间隔时间 #也可以用这种方法 #exec: 执行命令的方法进行监测,如果其退出码不为0,则认为容器正常 # command: # - cat # - /tmp/health #也可以用这种方法 #tcpSocket: //通过tcpSocket检查健康 # port: number lifecycle: #生命周期管理 postStart: #容器运行之前运行的任务 exec: command: - 'sh' - 'yum upgrade -y' preStop:#容器关闭之前运行的任务 exec: command: ['service httpd stop'] volumeMounts: #挂载持久存储卷 - name: volume #挂载设备的名字,与volumes[*].name 需要对应 mountPath: /data #挂载到容器的某个路径下 readOnly: True volumes: #定义一组挂载设备 - name: volume #定义一个挂载设备的名字 #meptyDir: {} hostPath: path: /opt #挂载设备类型为hostPath,路径为宿主机下的/opt,这里设备类型支持很多种 #nfs
(1)创建一个yaml文件
apiVersion: apps/v1beta2 kind: Deployment metadata: name: nginx-deployment spec: replicas: 3 selector: matchLabels: app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: nginx:1.10 ports: - containerPort: 80
(2)创建deployment
[root@master-01 YAML_k8s]# kubectl create -f nginx-deployment.yaml deployment.apps "nginx-deployment" created [root@master-01 YAML_k8s]# kubectl get pod -o wide NAME READY STATUS RESTARTS AGE IP NODE nginx-deployment-6b7b4d57b4-26wzj 1/1 Running 0 2m 10.20.184.83 master-01 nginx-deployment-6b7b4d57b4-9w7tm 1/1 Running 0 2m 10.20.190.60 node-01 nginx-deployment-6b7b4d57b4-mhh8t 1/1 Running 0 2m 10.20.254.108 node-03 [root@master-01 YAML_k8s]# kubectl get deployment NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE nginx-deployment 3 3 3 3 2m
(3)查看标签
[root@master-01 YAML_k8s]# kubectl get pod --show-labels NAME READY STATUS RESTARTS AGE LABELS nginx-deployment-6b7b4d57b4-26wzj 1/1 Running 0 3m app=nginx,pod-template-hash=2636081360 nginx-deployment-6b7b4d57b4-9w7tm 1/1 Running 0 3m app=nginx,pod-template-hash=2636081360 nginx-deployment-6b7b4d57b4-mhh8t 1/1 Running 0 3m app=nginx,pod-template-hash=2636081360
(4)通过标签查找Pod
[root@master-01 YAML_k8s]# kubectl get pod -l app=nginx NAME READY STATUS RESTARTS AGE nginx-deployment-6b7b4d57b4-26wzj 1/1 Running 0 6m nginx-deployment-6b7b4d57b4-9w7tm 1/1 Running 0 6m nginx-deployment-6b7b4d57b4-mhh8t 1/1 Running 0 6m
(5)deployment创建过程
Deployment 管理的是replicaset-controller,RC会创建Pod。Pod自身会下载镜像并启动镜像
[root@master-01 YAML_k8s]# kubectl describe rs nginx-deployment ... ... ... Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal SuccessfulCreate 33m replicaset-controller Created pod: nginx-deployment-6b7b4d57b4-9w7tm Normal SuccessfulCreate 33m replicaset-controller Created pod: nginx-deployment-6b7b4d57b4-26wzj Normal SuccessfulCreate 33m replicaset-controller Created pod: nginx-deployment-6b7b4d57b4-mhh8t [root@master-01 YAML_k8s]# kubectl describe pod nginx-deployment-6b7b4d57b4-26wzj ... ... ... Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled 36m default-scheduler Successfully assigned nginx-deployment-6b7b4d57b4-26wzj to master-01 Normal SuccessfulMountVolume 36m kubelet, master-01 MountVolume.SetUp succeeded for volume "default-token-v5vw9" Normal Pulled 36m kubelet, master-01 Container image "nginx:1.10" already present on machine Normal Created 36m kubelet, master-01 Created container Normal Started 36m kubelet, master-01 Started container
(6)升级镜像(nginx1.10-->nginx1.11)
[root@master-01 YAML_k8s]# kubectl set image deploy/nginx-deployment nginx=nginx:1.11 deployment.apps "nginx-deployment" image updated [root@master-01 YAML_k8s]# kubectl exec -it nginx-deployment-b96c97dc-2pxjf bash root@nginx-deployment-b96c97dc-2pxjf:/# nginx -V nginx version: nginx/1.11.13
升级镜像的过程是逐步进行的,pod不会一下子全部关闭,而是一个一个升级
(7)查看发布状态
[root@master-01 ~]# kubectl rollout status deploy/nginx-deployment deployment "nginx-deployment" successfully rolled out
(8)查看deployment历史修订版本
[root@master-01 ~]# kubectl rollout history deploy/nginx-deployment deployments "nginx-deployment" REVISION CHANGE-CAUSE 1 <none> 2 <none> # 显示历史有两个版本 [root@master-01 ~]# kubectl rollout history deploy/nginx-deployment --revision=1 deployments "nginx-deployment" with revision #1 Pod Template: Labels: app=nginx pod-template-hash=2636081360 Containers: nginx: Image: nginx:1.10 Port: 80/TCP Host Port: 0/TCP Environment: <none> Mounts: <none> Volumes: <none> [root@master-01 ~]# kubectl rollout history deploy/nginx-deployment --revision=2 deployments "nginx-deployment" with revision #2 Pod Template: Labels: app=nginx pod-template-hash=65275387 Containers: nginx: Image: nginx:1.11 Port: 80/TCP Host Port: 0/TCP Environment: <none> Mounts: <none> Volumes: <none>
(8)编辑deployment
[root@master-01 ~]# kubectl edit deploy/nginx-deployment # 将nginx版本改为1.12 ... ... ... spec: containers: - image: nginx:1.12 imagePullPolicy: IfNotPresent name: nginx ports: - containerPort: 80
升级过程:
[root@master-01 ~]# kubectl rollout status deploy/nginx-deployment Waiting for rollout to finish: 1 out of 3 new replicas have been updated... Waiting for rollout to finish: 1 out of 3 new replicas have been updated... Waiting for rollout to finish: 1 out of 3 new replicas have been updated... Waiting for rollout to finish: 2 out of 3 new replicas have been updated... Waiting for rollout to finish: 2 out of 3 new replicas have been updated... Waiting for rollout to finish: 2 out of 3 new replicas have been updated... Waiting for rollout to finish: 1 old replicas are pending termination... Waiting for rollout to finish: 1 old replicas are pending termination... deployment "nginx-deployment" successfully rolled out
(10)扩容/缩容(指定--replicas的数量)
[root@master-01 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE nginx-deployment-6b47cf4878-8mjkr 1/1 Running 0 1m nginx-deployment-6b47cf4878-kr978 1/1 Running 0 1m nginx-deployment-6b47cf4878-tvhvl 1/1 Running 0 1m [root@master-01 ~]# kubectl scale deploy/nginx-deployment --replicas=5 deployment.extensions "nginx-deployment" scaled [root@master-01 ~]# kubectl get pod NAME READY STATUS RESTARTS AGE nginx-deployment-6b47cf4878-6r5dz 0/1 ContainerCreating 0 4s nginx-deployment-6b47cf4878-7sjtt 0/1 ContainerCreating 0 4s nginx-deployment-6b47cf4878-8mjkr 1/1 Running 0 2m nginx-deployment-6b47cf4878-kr978 1/1 Running 0 2m nginx-deployment-6b47cf4878-tvhvl 1/1 Running 0 2m
(11)创建Service提供对外访问的接口
apiVersion: v1 kind: Service metadata: name: nginx-service labels: app: nginx spec: ports: - port: 88 targetPort: 80 selector: app: nginx #### apiVersion: 指定版本 kind: 类型 name: 指定服务名称 labels: 标签 port: Service 服务暴露的端口 targetPort: 容器暴露的端口 seletor: 关联的Pod的标签
创建service
# kubectl create -f nginx-service.yaml
查看service(访问Pod是有负载均衡的)
[root@master-01 YAML_k8s]# kubectl get svc/nginx-service NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE nginx-service ClusterIP 10.254.131.176 <none> 88/TCP 1m # curl 10.254.131.176:88 <!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>
对service的描述
# kubectl describe svc/nginx-service Name: nginx-service Namespace: default Labels: app=nginx Annotations: <none> Selector: app=nginx Type: ClusterIP IP: 10.254.131.176 Port: <unset> 88/TCP TargetPort: 80/TCP Endpoints: 10.20.184.19:80,10.20.184.84:80,10.20.190.62:80 + 2 more... Session Affinity: None Events: <none
(12)回滚到以前的版本
# kubectl rollout history deploy/nginx-deployment deployments "nginx-deployment" REVISION CHANGE-CAUSE 1 <none> 2 <none> 3 <none> # kubectl rollout history deploy/nginx-deployment --revision=3 deployments "nginx-deployment" with revision #3 Pod Template: Labels: app=nginx pod-template-hash=2603790434 Containers: nginx: Image: nginx:1.12 Port: 80/TCP Host Port: 0/TCP Environment: <none> Mounts: <none> Volumes: <none> # 回滚到上一个版本 # kubectl rollout undo deploy/nginx-deployment deployment.apps "nginx-deployment" # 查看版本 # kubectl describe deploy/nginx-deployment ... ... Labels: app=nginx Containers: nginx: Image: nginx:1.11
(13)回滚到指定版本
# kubectl rollout history deploy/nginx-deployment deployments "nginx-deployment" REVISION CHANGE-CAUSE 1 <none> 3 <none> 4 <none> # 指定版本 # kubectl rollout undo deploy/nginx-deployment --to-revision=1 deployment.apps "nginx-deployment"