【云原生 | Kubernetes 实战】03、手把手教你基于YAML文件运行pod应用

目录

一、通过资源清单文件创建第一个Pod

二、Pod 资源清单字段解读

常见字段详情可参考官网帮助命令文档：

三、Pod 常用命令

3.1 通过 kubectl run 命令行创建pod（不使用yaml文件）

四、Pod资源清单编写技巧 

4.1 通过 kubectl explain 查看定义Pod资源包含哪些字段。

4.2 查看 pod.metadata 字段如何定义

4.3 查看pod.spec字段如何定义

4.4 查看 pod.spec.containers 字段如何定义

4.5 查看 pod.spec.container.ports 字段如何定义

---

一、通过资源清单文件创建第一个Pod

[root@k8s-master01 pod-yaml]# vi pod-first.yaml apiVersion: v1kind: Podmetadata:  name: tomcat-test  namespace: default  labels:    app:  tomcatspec:  containers:  - name:  tomcat-java    image: tomcat:latest    imagePullPolicy: IfNotPresent    ports:    - containerPort: 8080

二、Pod 资源清单字段解读

#1. 创建pod 的资源清单参数详细帮助命令[root@k8s-master01 ~]# kubectl explain pod#2. pod 文件解读# 注意：每个英文冒号后面必须有一个空格[root@k8s-master01 pod-yaml]# vim pod-tomcat.yamlapiVersion: v1  # api版本为V1。通过 kubectl explain pod 命令查看kind: Pod       # 创建的资源类型。第一个 P 必须大写metadata:       # 创建对象。通过 kubectl explain pod.metadata 查看包含有哪些字段  name: tomcat-test    # Pod的名字  namespace: default   # Pod所在的名称空间（default 是默认名称空间）  labels:            app: tomcat     # Pod具有的标签spec:               # 通过 kubectl explain pod.spec 查看包含的字段  containers:       # 通过 kubectl explain pod.spec.containers 查看包含的字段；containers<[]Object> -required- 是对象列表，下面包含的第一个字段需要加 '-'  - name:  tomcat-java   # Pod里容器的名字        image: tomcat:latest  # 容器使用的镜像名称    imagePullPolicy: IfNotPresent    # 镜像拉取策略(使用本地的镜像）    ports:      # ports<[]Object> 对象列表中的第一个字段要加 '-'    - containerPort: 8080  # 容器暴露的端口#3. 创建 pod[root@k8s-master01 pod-yaml]# kubectl apply -f pod-first.yaml pod/tomcat-test created[root@k8s-master01 pod-yaml]# kubectl get podsNAME                         READY   STATUS    RESTARTS        AGEnginx-test-7767bdd4d-d5pqv   1/1     Running   1 (6h19m ago)   2d19hnginx-test-7767bdd4d-rqrm5   1/1     Running   1 (6h19m ago)   2d19htomcat-test                  1/1     Running   0               2s

常见字段详情可参考官网帮助命令文档：

metadata.annotations：Annotations | Kubernetesmetadata.labels：Labels and Selectors | Kubernetesmetadata.name：Object Names and IDs | Kubernetesmetadata.namespace：Namespaces | Kubernetesspec.containers.image：Images | Kubernetesspec.containers.imagePullPolicy:Images | Kubernetes

三、Pod 常用命令

# 更新资源清单文件[root@k8s-master01 pod-yaml]# kubectl apply -f pod-first.yaml# 查看pod是否创建成功[root@k8s-master01 pod-yaml]# kubectl get pods -l app=tomcat或者[root@k8s-master01 pod-yaml]# kubectl get pods -A# 查看pod的ip和pod调度到哪个节点上[root@k8s-master01 pod-yaml]# kubectl get pods -owide# 查看pod日志[root@k8s-master01 pod-yaml]# kubectl logs tomcat-test# 进入到创建的pod[root@k8s-master01 pod-yaml]# kubectl exec -it tomcat-test -- /bin/bash# 假如pod里有多个容器，进入到pod里的指定容器,-c 指定容器[root@k8s-master01 pod-yaml]# kubectl exec -it tomcat-test -c tomcat-java -- /bin/bash# 查看k8s集群中的名称空间[root@k8s-master01 pod-yaml]# kubectl get namespaces# 查看指定名称空间下的pod[root@k8s-master01 pod-yaml]# kubectl get pods -n default# 查看pod详细信息[root@k8s-master01 pod-yaml]# kubectl describe pods tomcat-test# 查看pod具有哪些标签：[root@k8s-master01 pod-yaml]# kubectl get pods --show-labels# 删除pod[root@k8s-master01 pod-yaml]# kubectl delete pods tomcat-test或者[root@k8s-master01 pod-yaml]# kubectl delete -f pod-first.yaml

3.1 通过 kubectl run 命令行创建pod（不使用yaml文件）

[root@k8s-master01 pod-yaml]# kubectl run tomcat --image=tomcat:latest --image-pull-policy='IfNotPresent' --port=8080pod/tomcat created您在 /var/spool/mail/root 中有新邮件[root@k8s-master01 pod-yaml]# kubectl get pods -owideNAME     READY   STATUS    RESTARTS   AGE   IP               NODE        NOMINATED NODE   READINESS GATEStomcat   1/1     Running   0          15s   10.244.169.136   k8s-node2   <none>           <none>

四、Pod资源清单编写技巧 

通过 kubectl explain 帮助指令查看每一个字段的含义，一步一步慢慢摸索下去。

4.1 通过 kubectl explain 查看定义Pod资源包含哪些字段。

[root@k8s-master01 pod-yaml]# kubectl explain podKIND:     PodVERSION:  v1# Pod是可以在主机上运行的容器的集合。这个资源是由客户端创建并调度到主机上。DESCRIPTION:     Pod is a collection of containers that can run on a host. This resource is     created by clients and scheduled onto hosts.FIELDS:   # APIVersion定义了对象,代表了一个版本为V1。   apiVersion<string>     APIVersion defines the versioned schema of this representation of an     object. Servers should convert recognized schemas to the latest internal     value, and may reject unrecognized values. More info:     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources   # Kind是字符串类型的值，代表了要创建的资源。服务器可以从客户端提交的请求推断出这个资源   kind<string>     Kind is a string value representing the REST resource this object     represents. Servers may infer this from the endpoint the client submits     requests to. Cannot be updated. In CamelCase. More info:     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds      # metadata是对象，定义元数据属性信息的   metadata<Object>     Standard object's metadata. More info:     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata   # spec制定了定义Pod的规格，里面包含容器的信息   spec<Object>     Specification of the desired behavior of the pod. More info:     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status   # status表示状态，这个不可以修改，定义pod的时候也不需要定义这个字段   status<Object>     Most recently observed status of the pod. This data may not be up to date.     Populated by the system. Read-only. More info:     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

4.2 查看 pod.metadata 字段如何定义

[root@k8s-master01 pod-yaml]# kubectl explain pod.metadataKIND:     PodVERSION:  v1# metadata是对象<Object>，下面可以有多个字段RESOURCE: metadata <Object>DESCRIPTION:     Standard object's metadata. More info:     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata     ObjectMeta is metadata that all persisted resources must have, which     includes all objects users must create.FIELDS:   # annotations是注解，map类型表示对应的值是key-value键值对，<string,string>表示 key 和value都是String类型的   annotations<map[string]string>     Annotations is an unstructured key value map stored with a resource that     may be set by external tools to store and retrieve arbitrary metadata. They     are not queryable and should be preserved when modifying objects. More     info: http://kubernetes.io/docs/user-guide/annotations······   # 创建的资源具有的标签。labels是标签，labels是map类型，map类型表示对应的值是key-value键值对，<string,string>表示 key和value都是String类型的   labels<map[string]string>     Map of string keys and values that can be used to organize and categorize     (scope and select) objects. May match selectors of replication controllers     and services. More info: http://kubernetes.io/docs/user-guide/labels   managedFields<[]Object>   name<string>    # 创建pod资源的名字   # 创建的资源所属的名称空间。namespaces划分了一个空间，在同一个namesace下的资源名字是唯一的，默认的名称空间是default。   namespace<string>     Namespace defines the space within which each name must be unique. An empty     namespace is equivalent to the "default" namespace, but "default" is the     canonical representation. Not all objects are required to be scoped to a     namespace - the value of this field for those objects will be empty.     Must be a DNS_LABEL. Cannot be updated. More info:     http://kubernetes.io/docs/user-guide/namespaces······

4.3 查看pod.spec字段如何定义

[root@k8s-master01 pod-yaml]# kubectl explain pod.specKIND:     PodVERSION:  v1RESOURCE: spec <Object># Pod的spec字段是用来描述Pod的DESCRIPTION:     Specification of the desired behavior of the pod. More info:     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status     PodSpec is a description of a pod.FIELDS:   # 表示Pod可以运行的最长时间，达到设置的值后，Pod会自动停止。   activeDeadlineSeconds<integer>     Optional duration in seconds the pod may be active on the node relative to     StartTime before the system will actively try to mark it failed and kill     associated containers. Value must be a positive integer.   affinity<Object>   # 定义亲和性的   automountServiceAccountToken<boolean>     AutomountServiceAccountToken indicates whether a service account token     should be automatically mounted.   # containers是对象列表，用来定义容器的，是必须字段。对象列表，表示下面有很多对象，对象列表下面的内容用 - 连接。   containers<[]Object> -required-     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.······

4.4 查看 pod.spec.containers 字段如何定义

[root@k8s-master01 pod-yaml]# kubectl explain pod.spec.containersKIND:     PodVERSION:  v1RESOURCE: containers <[]Object># container是定义在pod里面的，一个pod至少要有一个容器。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:······      # image是用来指定容器需要的镜像的    image<string>     Container image name. More info:     https://kubernetes.io/docs/concepts/containers/images This field is     optional to allow higher level config management to default or override     container images in workload controllers like Deployments and StatefulSets.   # 镜像拉取策略，pod是要调度到node节点的，那pod启动需要镜像，可以根据这个字段设置镜像拉取策略，支持如下三种：Always：不管本地是否存在镜像，都要重新拉取镜像Never： 从不拉取镜像IfNotPresent：如果本地存在，使用本地的镜像，本地不存在，从官方拉取镜像   imagePullPolicy<string>     Image pull policy. One of Always, Never, IfNotPresent. Defaults to Always     if :latest tag is specified, or IfNotPresent otherwise. Cannot be updated.     More info:     https://kubernetes.io/docs/concepts/containers/images#updating-images     Possible enum values:     - `"Always"` means that kubelet always attempts to pull the latest image.     Container will fail If the pull fails.     - `"IfNotPresent"` means that kubelet pulls if the image isn't present on     disk. Container will fail if the image isn't present and the pull fails.     - `"Never"` means that kubelet never pulls an image, but only uses a local     image. Container will fail if the image isn't present······   # name是必须字段，用来指定容器名字的   name<string> -required-     Name of the container specified as a DNS_LABEL. Each container in a pod     must have a unique name (DNS_LABEL). Cannot be updated.   # port是端口，属于对象列表   ports<[]Object>     List of ports to expose from the container. Not specifying a port here DOES     NOT prevent that port from being exposed. Any port which is listening on     the default "0.0.0.0" address inside a container will be accessible from     the network. Modifying this array with strategic merge patch may corrupt     the data. For more information See     https://github.com/kubernetes/kubernetes/issues/108255. Cannot be updated.······

4.5 查看 pod.spec.container.ports 字段如何定义

[root@k8s-master01 pod-yaml]# kubectl explain pod.spec.containers.portsKIND:     PodVERSION:  v1RESOURCE: ports <[]Object>DESCRIPTION:     List of ports to expose from the container. Not specifying a port here DOES     NOT prevent that port from being exposed. Any port which is listening on     the default "0.0.0.0" address inside a container will be accessible from     the network. Modifying this array with strategic merge patch may corrupt     the data. For more information See     https://github.com/kubernetes/kubernetes/issues/108255. Cannot be updated.     ContainerPort represents a network port in a single container.FIELDS:   # containerPort是必须字段， pod中的容器需要暴露的端口。   containerPort<integer> -required-     Number of port to expose on the pod's IP address. This must be a valid port     number, 0 < x < 65536.   # 将容器中的服务暴露到宿主机的端口上时，可以指定绑定的宿主机 IP。   hostIP<string>     What host IP to bind the external port to.   # 容器中的服务在宿主机上映射的端口   hostPort<integer>     Number of port to expose on the host. If specified, this must be a valid     port number, 0 < x < 65536. If HostNetwork is specified, this must match     ContainerPort. Most containers do not need this.   # 端口的名字   name<string>     If specified, this must be an IANA_SVC_NAME and unique within the pod. Each     named port in a pod must have a unique name. Name for the port that can be     referred to by services.······

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