K8S之pod入门和Lable
K8S之pod入门和Lable
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- Pod
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- Pod操作
- Label
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- 标签操作
Pod
- Pod是kubernetes集群进行管理的最小单元，程序要运行必须部署在容器中，而容器必须存在于Pod中。
Pod 可以认为是容器的封装，一个Pod中可以存在一个或者多个容器
Kubernetes在集群启动之后，集群中的各个组件也都是以Pod方式运行的。
[root@master ~]# kubectl get pod -n kube-system
NAME READY STATUS RESTARTS AGE
calico-kube-controllers-7dbc97f587-c8db6 1/1 Running 2 41h
calico-node-2k8tz 1/1 Running 2 41h
calico-node-f5dmh 1/1 Running 2 41h
calico-node-w47xc 1/1 Running 0 25h
coredns-7ff77c879f-bgxft 1/1 Running 2 44h
coredns-7ff77c879f-txgpk 1/1 Running 2 44h
etcd-master 1/1 Running 2 47h
kube-apiserver-master 1/1 Running 2 47h
kube-controller-manager-master 1/1 Running 4 47h
kube-proxy-p2qpc 1/1 Running 2 47h
kube-proxy-p4q77 1/1 Running 0 25h
kube-proxy-skfq5 1/1 Running 4 46h
kube-scheduler-master 1/1 Running 5 47h
Pod操作
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创建并运行
kubernetes没有提供单独运行pod的命令，都是通过Pod控制器来实现的
# 命令格式： kubectl run (pod控制器名称) [参数]
# --image 指定Pod的镜像
# --port 指定端口
# --namespace 指定namespace
[root@master ~]# kubectl run nginx --image=nginx:latest --port=80 --namespace dev
deployment.apps/nginx created
- 查看pod信息
# 查看Pod基本信息
[root@master ~]# kubectl get pods -n dev
NAME READY STATUS RESTARTS AGE
nginx 1/1 Running 0 43s
# 查看Pod的详细信息
[root@master ~]# kubectl describe pod nginx -n dev
Name: nginx
Namespace: dev
Priority: 0
Node: node1/192.168.1.105
Start Time: Wed, 01 Sep 2021 10:29:19 +0800
Labels: env=test
version=3.0
Annotations: cni.projectcalico.org/podIP: 10.244.166.143/32
cni.projectcalico.org/podIPs: 10.244.166.143/32
Status: Running
IP: 10.244.166.143
IPs:
IP: 10.244.166.143
Containers:
pod:
Container ID: docker://ce4bf985af9f01ac31e300becaf47aaf898a60b91936dd09ee1f417f71d34120
Image: nginx:latest
Image ID: docker-pullable://nginx@sha256:4d4d96ac750af48c6a551d757c1cbfc071692309b491b70b2b8976e102dd3fef
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Wed, 01 Sep 2021 10:29:56 +0800
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-spd9p (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
default-token-spd9p:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-spd9p
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 15m default-scheduler Successfully assigned dev/nginx to node1
Normal Pulling 15m kubelet, node1 Pulling image "nginx:latest"
Normal Pulled 14m kubelet, node1 Successfully pulled image "nginx:latest"
Normal Created 14m kubelet, node1 Created container pod
Normal Started 14m kubelet, node1 Started container pod
- 访问pod，获取pod运行在哪个节点上
# 获取podIP 和 pod 运行在哪个节点上
[root@master ~]# kubectl get pods -n dev -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx 1/1 Running 0 16m 10.244.166.143 node1 <none> <none>
# 访问pod
[root@master ~]# curl http://10.244.166.143:80
<!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>
- 删除指定pod
[root@master ~]# kubectl delete pod nginx -n dev
pod "nginx" deleted
# 此时，显示删除Pod成功，但是再查询，发现又新产生了一个
[root@master ~]# kubectl get pods -n dev
NAME READY STATUS RESTARTS AGE
nginx 1/1 Running 0 21s
# 这是因为当前Pod是由Pod控制器创建的，控制器会监控Pod状况，一旦发现Pod死亡，会立即重建
# 此时要想删除Pod，必须删除Pod控制器
# 先来查询一下当前namespace下的Pod控制器
[root@master ~]# kubectl get deploy -n dev
NAME READY UP-TO-DATE AVAILABLE AGE
nginx 1/1 1 1 9m7s
# 接下来，删除此PodPod控制器
[root@master ~]# kubectl delete deploy nginx -n dev
deployment.apps "nginx" deleted
# 稍等片刻，再查询Pod，发现Pod被删除了
[root@master ~]# kubectl get pods -n dev
No resources found in dev namespace.
- 基于配置文件的创建
vim pod-nginx.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx
namespace: dev
spec:
containers:
- image: nginx:latest
name: pod
ports:
- name: nginx-port
containerPort: 80
protocol: TCP
- 创建：
kubectl create -f pod-nginx.yaml
- 删除：
kubectl delete -f pod-nginx.yaml
Label
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Label 它的作用就是在资源上添加标识，用来对他们进行区分和选择
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Label 会以key=value键值对的形式附加到各种对象上，如Node、pod、Service等
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一个资源可以定义任意数量的Label，同一个Label也可以被添加到任意数量的资源对象上去
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Label通常在资源定义时确定，当然也可以在对象创建后动态添加或者删除
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为什么要有Label？
可以实现分组
namespace实现的分组是 不同的namespace之间是不同的 适合不同项目的分组 一个项目里面的前端和后端也需要分组 但是还要互通 这个时候就可以通过Label分组。
标签定义完毕之后，还要考虑到标签的选择，这就要使用到 Label Selector
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Label用于给某个资源对象定义标识
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Label Selector 用于查询和筛选拥有某些标签的资源对象
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两种Label Selector
基于等式的Label Selector
name = slave: 选择所有包含Label中key="name"且value="slave"的对象 env != production: 选择所有包括Label中的key="env"且value不等于"production"的对象基于集合的Label Selector
- name in (master, slave): 选择所有包含Label中的key="name"且value="master"或"slave"的对象 name not in (frontend): 选择所有包含Label中的key="name"且value不等于"frontend"的对象
标签的选择条件可以使用多个，此时将多个Label Selector进行组合，使用逗号","进行分隔即可。例如：
name=slave，env!=production
name not in (frontend)，env!=production
标签操作
- 命令方式
# 为pod资源打标签
[root@master ~]# kubectl label pod nginx-pod version=1.0 -n dev
pod/nginx-pod labeled
# 为pod资源更新标签
[root@master ~]# kubectl label pod nginx-pod version=2.0 -n dev --overwrite
pod/nginx-pod labeled
# 查看标签
[root@master ~]# kubectl get pod nginx-pod -n dev --show-labels
NAME READY STATUS RESTARTS AGE LABELS
nginx-pod 1/1 Running 0 10m version=2.0
# 筛选标签
[root@master ~]# kubectl get pod -n dev -l version=2.0 --show-labels
NAME READY STATUS RESTARTS AGE LABELS
nginx-pod 1/1 Running 0 17m version=2.0
[root@master ~]# kubectl get pod -n dev -l version!=2.0 --show-labels
No resources found in dev namespace.
#删除标签
[root@master ~]# kubectl label pod nginx-pod version- -n dev
pod/nginx-pod labeled
- 配置文件的方式
apiVersion: v1
kind: Pod
metadata:
name: nginx
namespace: dev
labels:
version: "3.0"
env: "test"
spec:
containers:
- image: nginx:latest
name: pod
ports:
- name: nginx-port
containerPort: 80
protocol: TCP
执行命令创建kubectl apply -f pod-nginx.yaml
# 查看
[root@master ~]# kubectl get pods -n dev --show-labels
NAME READY STATUS RESTARTS AGE LABELS
nginx 1/1 Running 0 69m env=test,version=3.0