05-资源清单定义入门

kubernetes
资源类型主要有:
service
pod
workload：运行程序对外提供服务de, Pod
服务发现及均衡
配置与存储：Volume,CSI 存储卷

查看pods 资源配置清单

创建资源的方法:

apiserver 仅接受JSON格式的资源定义;
yaml格式来提供配置清单,apiserver 可自动将其转为json格式,而后在执行；

大部分资源的配置清单都有5个字段组成:
字段一:apiVersion 标识方式是 group/version 的方式,
通过 kubectl api-versions 查看 apiversion 所支持的版本
字段二:kind: 资源类别
字段三:metadata: 元数据
　　　　name
　　　　namespace
　　　　labels 标签
　　　　annotations 资源注解

　　　　每个资源的引用PATH
　　　　/api/$GROUP/$VERSION/$NAMESPACE/$TYPE/$NAME
字段四: spec: 期望的状态，disired state
　　 status：当前状态，current state,本字段由 kubernetes 集群维护
kubernetes有内建的格式使用kubectl explain pods/node 查看格式需要的字段

[root@master ~]# kubectl explain pods
KIND:     Pod
VERSION:  v1

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   <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/api-conventions.md#resources

   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/api-conventions.md#types-kinds

   metadata     <Object>
     Standard object's metadata. More info:
     https://git.k8s.io/community/contributors/devel/api-conventions.md#metadata

   spec <Object>
     Specification of the desired behavior of the pod. More info:
     https://git.k8s.io/community/contributors/devel/api-conventions.md#spec-and-status

   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/api-conventions.md#spec-and-status

kubectl explain pods

　　如果要查看二级字段的内建格式可以使用

[root@master ~]# kubectl explain pods.apiVersion
KIND:     Pod
VERSION:  v1

FIELD:    apiVersion <string>

DESCRIPTION:
     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/api-conventions.md#resources

kubectl explain pods.apiVersion

创建一个简单的资源清单

apiVersion: v1
kind: Pod
metadata:
        name: pod-demo-new
        namespace: default
        labels:
                app: myapp
                tier: fronetend
spec:
        containers:
        - name: myapp-new
          image: nginx:1.15-alpine
        - name: busybox
          image: busybox:latest
          command:
          - "/bin/sh"
          - "-c"
          - "echo $(date) >>/usr/share/nginx/html/index.html; sleep 5"

使用kubectl create -f pod-demo.yaml创建资源

kubectl create -f pod-demo.yaml

通过kubectl describe pods pod-demo-new 查看新创建的资源详细信息

[root@master mainfests]# kubectl describe pods pod-demo-new
Name:               pod-demo-new
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               node01/192.168.122.221
Start Time:         Fri, 12 Apr 2019 11:42:26 +0800
Labels:             app=myapp
                    tier=fronetend
Annotations:        <none>
Status:             Running
IP:                 10.244.1.17
Containers:
  myapp-new:
    Container ID:   docker://567a2553f2b83da37c11829814bc37c79e6460cc701cdc9f13286c662cc0f692
    Image:          nginx:1.15-alpine
    Image ID:       docker-pullable://nginx@sha256:b05adda06363b850ade704048e15e076d493429badf0b3df275acd8ca428b3fe
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Fri, 12 Apr 2019 11:42:28 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-dvm6l (ro)
  busybox:
    Container ID:  docker://0ce6d58ba6a6f405e9a1b68bc5c9ac5b31df5bf0587c9dccb2dd85de086a8320
    Image:         busybox:latest
    Image ID:      docker-pullable://busybox@sha256:954e1f01e80ce09d0887ff6ea10b13a812cb01932a0781d6b0cc23f743a874fd
    Port:          <none>
    Host Port:     <none>
    Command:
      /bin/sh
      -c
      echo $(date) >>/usr/share/nginx/html/index.html; sleep 5
    State:          Waiting
      Reason:       CrashLoopBackOff
    Last State:     Terminated
      Reason:       Completed
      Exit Code:    0
      Started:      Fri, 12 Apr 2019 11:46:41 +0800
      Finished:     Fri, 12 Apr 2019 11:46:46 +0800
    Ready:          False
    Restart Count:  5
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-dvm6l (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             False 
  ContainersReady   False 
  PodScheduled      True 
Volumes:
  default-token-dvm6l:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-dvm6l
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type     Reason     Age                    From               Message
  ----     ------     ----                   ----               -------
  Normal   Scheduled  5m50s                  default-scheduler  Successfully assigned default/pod-demo-new to node01
  Normal   Pulled     5m49s                  kubelet, node01    Container image "nginx:1.15-alpine" already present on machine
  Normal   Created    5m48s                  kubelet, node01    Created container myapp-new
  Normal   Started    5m48s                  kubelet, node01    Started container myapp-new
  Normal   Pulling    4m29s (x4 over 5m48s)  kubelet, node01    Pulling image "busybox:latest"
  Normal   Pulled     4m23s (x4 over 5m40s)  kubelet, node01    Successfully pulled image "busybox:latest"
  Normal   Created    4m23s (x4 over 5m39s)  kubelet, node01    Created container busybox
  Normal   Started    4m23s (x4 over 5m39s)  kubelet, node01    Started container busybox
  Warning  BackOff    48s (x17 over 5m18s)   kubelet, node01    Back-off restarting failed container
[root@master mainfests]#

kubectl describe pods pod-demo-new

[root@master mainfests]# kubectl logs pod-demo-new myapp-new
10.244.0.0 - - [12/Apr/2019:03:46:05 +0000] "GET / HTTP/1.1" 200 612 "-" "ELinks/0.12pre6 (textmode; Linux; -)" "-"
10.244.0.0 - - [12/Apr/2019:03:46:07 +0000] "GET / HTTP/1.1" 200 612 "-" "ELinks/0.12pre6 (textmode; Linux; -)" "-"
10.244.0.0 - - [12/Apr/2019:03:46:07 +0000] "GET / HTTP/1.1" 200 612 "-" "ELinks/0.12pre6 (textmode; Linux; -)" "-"
10.244.0.0 - - [12/Apr/2019:03:46:08 +0000] "GET / HTTP/1.1" 200 612 "-" "ELinks/0.12pre6 (textmode; Linux; -)" "-"
[root@master mainfests]#

通过:kubectl logs pod-demo-new myapp-new 查看日志