通过资源清单文件创建第一个Pod

解压镜像：把tomcat.tar.gz上传到k8snode1和k8snode2节点
链接：https://pan.baidu.com/s/1qLcoJDqYSC9dfiDcWY-s0g?pwd=44ad
提取码：44ad

ctr -n=k8s.io images import  tomcat.tar.gz

vim pod-first.yaml
apiVersion: v1
kind: Pod
metadata:name: tomcat-testnamespace: defaultlabels:app:  tomcat
spec:containers:- name:  tomcat-javaports:- containerPort: 8080image: tomcat/tomcat-8.5-jre8:v1imagePullPolicy: IfNotPresent

更新资源清单文件

kubectl apply -f pod-first.yaml 

查看pod是否创建成功

kubectl get pods -l app=tomcat

查看pod的ip和pod调度到哪个节点上

kubectl get pods -owide

查看pod日志

kubectl logs tomcat-test

进入到刚才创建的pod，刚才创建的pod名字是tomcat-test

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

kubectl exec -it tomcat-test -c tomcat-java -- /bin/bash

查看pod详细信息

kubectl describe pods tomcat-test

查看pod具有哪些标签：

kubectl get pods --show-labels

删除pod

#kubectl delete pods tomcat-test
kubectl delete -f pod-first.yaml

我们上面创建的pod是一个自主式pod，也就是通过pod创建一个应用程序，如果pod出现故障停掉，那么我们通过pod部署的应用也就会停掉，不安全， 还有一种控制器管理的pod，通过控制器创建pod，可以对pod的生命周期做管理，可以定义pod的副本数，如果有一个pod意外停掉，那么会自动起来一个pod替代之前的pod

通过kubectl run创建Pod

kubectl run tomcat --image=tomcat/tomcat-8.5-jre8:v1  --image-pull-policy='IfNotPresent'  --port=8080

Pod资源清单字段解读

vim pod-tomcat.yaml
apiVersion: v1  #api版本
kind: Pod       #创建的资源
metadata:    name: tomcat-test  #Pod的名字namespace: default   #Pod所在的名称空间labels:app:  tomcat     #Pod具有的标签
spec:containers:- name:  tomcat-java   #Pod里容器的名字ports:- containerPort: 8080  #容器暴露的端口image: tomcat/tomcat-8.5-jre8:v1  #容器使用的镜像imagePullPolicy: IfNotPresent    #镜像拉取策略

Pod资源清单编写技巧

通过kubectl explain 查看定义Pod资源包含哪些字段。

kubectl explain pod

KIND:     Pod
VERSION:  v1
DESCRIPTION:Pod is a collection of containers that can run on a host. This resource iscreated by clients and scheduled onto hosts.
[Pod是可以在主机上运行的容器的集合。此资源是由客户端创建并安排到主机上。]FIELDS:apiVersion	<string>APIVersion defines the versioned schema of this representation of anobject. Servers should convert recognized schemas to the latest internalvalue, and may reject unrecognized values. More info:https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources
[APIVersion定义了对象,代表了一个版本。]kind	<string>Kind is a string value representing the REST resource this objectrepresents. Servers may infer this from the endpoint the client submitsrequests to. Cannot be updated. In CamelCase. More info:https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds
[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。]metadata	<Object>Standard object's metadata. More info:https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata
[metadata是对象，定义元数据属性信息的]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
[spec制定了定义Pod的规格，里面包含容器的信息]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
[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]

查看pod.metadata字段如何定义

kubectl explain pod.metadata

KIND:     Pod
VERSION:  v1
RESOURCE: metadata <Object># metadata是对象<Object>，下面可以有多个字段DESCRIPTION:Standard object's metadata. More info:https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadataObjectMeta is metadata that all persisted resources must have, whichincludes all objects users must create.FIELDS:annotations	<map[string]string>Annotations is an unstructured key value map stored with a resource thatmay be set by external tools to store and retrieve arbitrary metadata. Theyare not queryable and should be preserved when modifying objects. Moreinfo: http://kubernetes.io/docs/user-guide/annotations
# 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

例如：

"metadata": {"annotations": {"key1" : "value1","key2" : "value2"}
}

用Annotation来记录的信息包括：
build信息、release信息、Docker镜像信息等，例如时间戳、release id号、镜像hash值、docker registry地址等；
日志库、监控库、分析库等资源库的地址信息；
程序调试工具信息，例如工具名称、版本号等；
团队的联系信息，例如电话号码、负责人名称、网址等。

   clusterName	<string>The name of the cluster which the object belongs to. This is used todistinguish resources with same name and namespace in different clusters.This field is not set anywhere right now and apiserver is going to ignoreit if set in create or update request.
#对象所属群集的名称。这是用来区分不同集群中具有相同名称和命名空间的资源。此字段现在未设置在任何位置，apiserver将忽略它，如果设置了就使用设置的值creationTimestamp	<string>deletionGracePeriodSeconds	<integer>deletionTimestamp	<string>finalizers	<[]string>generateName	<string>generation	<integer>labels	<map[string]string> #创建的资源具有的标签
Map of string keys and values that can be used to organize and categorize(scope and select) objects. May match selectors of replication controllersand services. More info: http://kubernetes.io/docs/user-guide/labels
#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managedFields	<[]Object>name	<string>           #创建的资源的名字namespace	<string>      #创建的资源所属的名称空间
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
# 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。ownerReferences	<[]Object>resourceVersion	<string>selfLink	<string>uid	<string>

查看pod.spec字段如何定义

kubectl explain pod.spec

KIND:     Pod
VERSION:  v1
RESOURCE: spec <Object>
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-statusPodSpec is a description of a pod.
#Pod的spec字段是用来描述Pod的FIELDS:activeDeadlineSeconds	<integer>
#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。
affinity	<Object>#定义亲和性的automountServiceAccountToken	<boolean>containers	<[]Object> -required-
#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。dnsConfig	<Object>dnsPolicy	<string>enableServiceLinks	<boolean>ephemeralContainers	<[]Object>hostAliases	<[]Object>hostIPC	<boolean>hostNetwork	<boolean>hostPID	<boolean>hostname	<string>imagePullSecrets	<[]Object>initContainers	<[]Object>nodeName	<string>nodeSelector	<map[string]string>overhead	<map[string]string>preemptionPolicy	<string>priority	<integer>priorityClassName	<string>readinessGates	<[]Object>restartPolicy	<string>runtimeClassName	<string>schedulerName	<string>securityContext	<Object>serviceAccount	<string>serviceAccountName	<string>setHostnameAsFQDN	<boolean>shareProcessNamespace	<boolean>subdomain	<string>terminationGracePeriodSeconds	<integer>tolerations	<[]Object>topologySpreadConstraints	<[]Object>volumes	<[]Object>

查看pod.spec.containers字段如何定义

kubectl explain pod.spec.containers

KIND:     Pod
VERSION:  v1RESOURCE: containers <[]Object>
DESCRIPTION:List of containers belonging to the pod. Containers cannot currently beadded or removed. There must be at least one container in a Pod. Cannot beupdated.A single application container that you want to run within a pod.
#container是定义在pod里面的，一个pod至少要有一个容器。FIELDS:args	<[]string>command	<[]string>env	<[]Object>envFrom	<[]Object>image	<string>
#image是用来指定容器需要的镜像的imagePullPolicy	<string>
#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lifecycle	<Object>livenessProbe	<Object>name	<string> -required-
#name是必须字段，用来指定容器名字的ports	<[]Object>
#port是端口，属于对象列表readinessProbe	<Object>resources	<Object>securityContext	<Object>startupProbe	<Object>stdin	<boolean>stdinOnce	<boolean>terminationMessagePath	<string>terminationMessagePolicy	<string>tty	<boolean>volumeDevices	<[]Object>volumeMounts	<[]Object>workingDir	<string>

查看pod.spec.container.ports字段如何定义

kubectl explain pod.spec.containers.ports

KIND:     Pod
VERSION:  v1
RESOURCE: ports <[]Object>
DESCRIPTION:List of ports to expose from the container. Exposing a port here gives thesystem additional information about the network connections a containeruses, but is primarily informational. Not specifying a port here DOES NOTprevent that port from being exposed. Any port which is listening on thedefault "0.0.0.0" address inside a container will be accessible from thenetwork. Cannot be updated.ContainerPort represents a network port in a single container.
FIELDS:containerPort	<integer> -required-Number of port to expose on the pod's IP address. This must be a valid portnumber, 0 < x < 65536.
#containerPort是必须字段， pod中的容器需要暴露的端口。hostIP	<string>What host IP to bind the external port to.
#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。hostPort	<integer>Number of port to expose on the host. If specified, this must be a validport number, 0 < x < 65536. If HostNetwork is specified, this must matchContainerPort. Most containers do not need this.
#容器中的服务在宿主机上映射的端口name	<string>If specified, this must be an IANA_SVC_NAME and unique within the pod. Eachnamed port in a pod must have a unique name. Name for the port that can bereferred to by services.
#端口的名字protocol	<string>Protocol for port. Must be UDP, TCP, or SCTP. Defaults to "TCP".