什么是label
Label以key/value键值对的形式附加到任何对象上，如Pod，Service，Node， RC（ReplicationController）/RS（ReplicaSet）等。
一个资源如果需要找到其它关联的资源比如rc匹配pod、deployment匹配rs都是通过selector选择对应的lable达到关联其它对象的目的。
k8s对象的label在资源的metadata定义，例如之前学习过的deplyment定义文件
标签的增删改查
label查询
#查询某一类资源或者指定某个资源查询其label信息 [root@k8s-01 ~]# kubectl get deployment --show-labels NAME READY UP-TO-DATE AVAILABLE AGE LABELS nginx-d 3/3 3 3 2d21h app=nginx wordpress 1/1 1 1 49d app=wordpress,tier=frontend wordpress-mysql 1/1 1 1 49d app=wordpress,tier=mysql You have new mail in /var/spool/mail/root [root@k8s-01 ~]# kubectl get deployment nginx-d --show-labels NAME READY UP-TO-DATE AVAILABLE AGE LABELS nginx-d 3/3 3 3 2d21h app=nginx [root@k8s-01 ~]# kubectl get pods --show-labels NAME READY STATUS RESTARTS AGE LABELS nginx-d-659bf7c684-22nc8 1/1 Running 1 2d20h app=nginx,pod-template-hash=659bf7c684 nginx-d-659bf7c684-9l9jk 1/1 Running 1 2d20h app=nginx,pod-template-hash=659bf7c684 nginx-d-659bf7c684-tmtkl 1/1 Running 1 2d20h app=nginx,pod-template-hash=659bf7c684 wordpress-69c467c658-r7c45 1/1 Running 11 49d app=wordpress,pod-template-hash=69c467c658,tier=frontend-pod wordpress-mysql-6c696cddc9-r6dvx 1/1 Running 15 42d app=wordpress,pod-template-hash=6c696cddc9,tier=mysql-pod [root@k8s-01 ~]# kubectl get pods nginx-d-659bf7c684-22nc8 --show-labels NAME READY STATUS RESTARTS AGE LABELS nginx-d-659bf7c684-22nc8 1/1 Running 1 2d20h app=nginx,pod-template-hash=659bf7c684
label的增加 删除 修改
#指定对象label的添加和删除，添加使用key=value,删除keu-,修改key=value --overwrite [root@k8s-01 ~]# kubectl get pods nginx-d-659bf7c684-22nc8 --show-labels NAME READY STATUS RESTARTS AGE LABELS nginx-d-659bf7c684-22nc8 1/1 Running 1 2d20h app=nginx,pod-template-hash=659bf7c684 [root@k8s-01 ~]# [root@k8s-01 ~]# kubectl label pods nginx-d-659bf7c684-22nc8 test=label pod/nginx-d-659bf7c684-22nc8 labeled [root@k8s-01 ~]# kubectl get pods nginx-d-659bf7c684-22nc8 --show-labels NAME READY STATUS RESTARTS AGE LABELS nginx-d-659bf7c684-22nc8 1/1 Running 1 2d20h app=nginx,pod-template-hash=659bf7c684,test=label [root@k8s-01 ~]# kubectl label pods nginx-d-659bf7c684-22nc8 test- pod/nginx-d-659bf7c684-22nc8 labeled [root@k8s-01 ~]# kubectl get pods nginx-d-659bf7c684-22nc8 --show-labels NAME READY STATUS RESTARTS AGE LABELS nginx-d-659bf7c684-22nc8 1/1 Running 1 2d20h app=nginx,pod-template-hash=659bf7c684 [root@k8s-01 ~]# kubectl label pods nginx-d-659bf7c684-22nc8 test=label1 pod/nginx-d-659bf7c684-22nc8 labeled [root@k8s-01 ~]# kubectl get pods nginx-d-659bf7c684-22nc8 --show-labels NAME READY STATUS RESTARTS AGE LABELS nginx-d-659bf7c684-22nc8 1/1 Running 1 2d20h app=nginx,pod-template-hash=659bf7c684,test=label1 [root@k8s-01 ~]# kubectl label pods nginx-d-659bf7c684-22nc8 test=label2 error: 'test' already has a value (label1), and --overwrite is false [root@k8s-01 ~]# kubectl label pods nginx-d-659bf7c684-22nc8 test=label2 --overwrite pod/nginx-d-659bf7c684-22nc8 labeled [root@k8s-01 ~]# kubectl get pods nginx-d-659bf7c684-22nc8 --show-labels NAME READY STATUS RESTARTS AGE LABELS nginx-d-659bf7c684-22nc8 1/1 Running 1 2d20h app=nginx,pod-template-hash=659bf7c684,test=label2
一般建议k8s对象的label在定义文件中进行定义和修改
nodeselector
nodeselector是pod的专有的选择器，在资源定义文件中可以指定pod在哪些node节点上创建。不配置该参数的话k8s会根据自身算法选择相应的node来部署pod
不配置nodeselector情况下pod的分布，如果有多个node则pod一定分布在多个pod上。
[root@k8s-01 ~]# kubectl get deployment -o wide NAME READY UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR nginx-d 3/3 3 3 2d21h nginx nginx:1.18 app=nginx [root@k8s-01 ~]# kubectl get pod -o wide|grep nginx-d nginx-d-659bf7c684-22nc8 1/1 Running 1 2d21h 10.244.2.52 k8s-03 <none> <none> nginx-d-659bf7c684-9l9jk 1/1 Running 1 2d21h 10.244.2.53 k8s-03 <none> <none> nginx-d-659bf7c684-tmtkl 1/1 Running 1 2d21h 10.244.1.71 k8s-02 <none> <none>
查询环境node信息，给node打上label
[root@k8s-01 ~]# kubectl get nodes --show-labels NAME STATUS ROLES AGE VERSION LABELS k8s-01 Ready master 61d v1.15.0 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-01,kubernetes.io/os=linux,node-role.kubernetes.io/master= k8s-02 Ready <none> 61d v1.15.0 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-02,kubernetes.io/os=linux k8s-03 Ready <none> 61d v1.15.0 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-03,kubernetes.io/os=linux [root@k8s-01 ~]# kubectl label nodes k8s-02 selectortest=k8s-02 node/k8s-02 labeled [root@k8s-01 ~]# kubectl get nodes --show-labels NAME STATUS ROLES AGE VERSION LABELS k8s-01 Ready master 61d v1.15.0 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-01,kubernetes.io/os=linux,node-role.kubernetes.io/master= k8s-02 Ready <none> 61d v1.15.0 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-02,kubernetes.io/os=linux,selectortest=k8s-02 k8s-03 Ready <none> 61d v1.15.0 beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-03,kubernetes.io/os=linux
deployment定义文件中pod部分使用nodeselector指定node创建Pod
#pod对象定义中指定nodeSelector后pod调度的效果 [root@k8s-01 ~]# kubectl get deployment NAME READY UP-TO-DATE AVAILABLE AGE wordpress 1/1 1 1 49d wordpress-mysql 1/1 1 1 49d [root@k8s-01 ~]# kubectl get deployment|grep nginx [root@k8s-01 ~]# kubectl create -f deployment_demo.yml deployment.apps/nginx-d created [root@k8s-01 ~]# kubectl get deployment|grep nginx nginx-d 0/3 3 0 3s [root@k8s-01 ~]# kubectl get pods -o wide|grep nginx-d nginx-d-8668fb97b9-7tw25 1/1 Running 0 43s 10.244.1.75 k8s-02 <none> <none> nginx-d-8668fb97b9-9hfmb 1/1 Running 0 43s 10.244.1.74 k8s-02 <none> <none> nginx-d-8668fb97b9-vlzgt 0/1 ContainerCreating 0 43s <none> k8s-02 <none> <none>
