[cloud native | learn kubernetes from scratch] VIII. Namespace resource quotas and labels

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namespacs Use case sharing

# Create a  test  Namespace  
[[email protected] ~]# kubectl create ns test 

# Delete namespace 
[[email protected] ~]# kubectl delete ns test

# Switch namespace  
[[email protected] ~]# kubectl config set-context --current --namespace=kube-system
[[email protected] ~]# kubectl get pods
NAME                                READY   STATUS    RESTARTS   AGE
coredns-7ff77c879f-272f4            1/1     Running   3          12d
coredns-7ff77c879f-flkxx            1/1     Running   3          12d
# After switching namespaces ,kubectl get pods  If you don't specify -n, What I'm looking at is  kube-system  Namespace resources . 
 
# See which resources belong to namespace level   If you do not specify a namespace when creating resources, it will be in the default namespace  pod It's namespace level 
[[email protected] ~]# kubectl api-resources --namespaced=true

namespace Resource limits

namespace It's a namespace , There are many resources in it , Then we can make a restriction on namespace resources , Prevent resources deployed by this namespace from exceeding the limit .

How to namespace What about resource limits ？

[[email protected] ~]# mkdir pp
[[email protected] ~]# cd pp
[[email protected] ~]# vim namespace-pp.yaml 
apiVersion: v1 
kind: ResourceQuota
metadata:
  name: mem-cpu-quota
  namespace: test
spec:
  hard:
    requests.cpu: "2"
    requests.memory: 2Gi
    limits.cpu: "4"
    limits.memory: 4Gi

Created ResourceQuota The object will be in test Add the following restrictions to the namespace ：
Each container must set a memory request （memory request）, Memory limit （memory limit）,cpu request （cpu request） and cpu limit （cpu limit）.
The total amount of memory requests for all containers must not exceed 2 GiB.
The total memory limit for all containers must not exceed 4 GiB.
Of all containers CPU The total amount requested must not exceed 2 CPU.
Of all containers CPU The total limit shall not exceed 4 CPU.

[[email protected] pp]# kubectl apply -f namespace-pp.yaml 
resourcequota/mem-cpu-quota created
[[email protected] pp]# kubectl describe ns test
Name:         test
Labels:       <none>
Annotations:  <none>
Status:       Active

Resource Quotas
 Name:            mem-cpu-quota
 Resource         Used  Hard
 --------         ---   ---
 limits.cpu       0     4
 limits.memory    0     4Gi
 requests.cpu     0     2
 requests.memory  0     2Gi
 
No LimitRange resource.

# establish  pod  Resource limits must be set when , Otherwise, the creation fails , as follows ： 
[[email protected] pp]# vim pod-test.yaml 
apiVersion: v1 
kind: Pod 
metadata: 
  name: pod-test 
  namespace: test 
  labels: 
    app: tomcat-pod-test 
spec: 
  containers: 
  - name: tomcat-test 
    ports: 
    - containerPort: 8080 
    image: tomcat
    imagePullPolicy: IfNotPresent 
    resources: 
      requests: 
        memory: "100Mi" 
        cpu: "500m" 
      limits: 
        memory: "2Gi" 
        cpu: "2" 

[[email protected] pp]# kubectl get pods -n test
NAME       READY   STATUS    RESTARTS   AGE
pod-test   1/1     Running   0          8s
[[email protected] pp]# kubectl describe pods pod-test -n test
Name:         pod-test
Namespace:    test
Priority:     0
Node:         k8snode/192.168.11.141
Start Time:   Fri, 08 Jul 2022 21:31:01 -0700
Labels:       app=tomcat-pod-test
Annotations:  Status:  Running
IP:           10.244.2.13
IPs:
  IP:  10.244.2.13
Containers:
  tomcat-test:
    Container ID:   docker://b8604abe672c701f1ea8d027568b375989e12061090e1c5d951dae637af9b726
    Image:          tomcat
    Image ID:       docker-pullable://[email protected]:9dee185c3b161cdfede1f5e35e8b56ebc9de88ed3a79526939701f3537a52324
    Port:           8080/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Fri, 08 Jul 2022 21:31:02 -0700
    Ready:          True
    Restart Count:  0
    Limits:
      cpu:     2
      memory:  2Gi
    Requests:
      cpu:        500m
      memory:     100Mi
    Environment:  <none>
    Mounts:

What is a label ？

The labels are actually a pair key/value , Is associated to an object , such as Pod, In the use of tags, we tend to be able to represent the special characteristics of objects , You can see this at a glance Pod What is it , Tags can be used to divide specific objects （ Such as version , Service type, etc ）, Tags can be defined directly when creating an object , It can also be modified at any time later , Each object can have multiple labels , however ,key Value must be the only . After creating tags, it is also convenient for us to group and manage resources . If the pod tagging , Then you can use the tag to view 、 Delete specified pod.
stay k8s in , Most resources can be labeled .

to pod Resource tagging

# To what already exists  pod  tagging   Express this pod The version is v1
[[email protected] pp]# kubectl label pods pod-first release=v1 
# Check whether the label is printed successfully   View the specified pod
[[email protected] pp]# kubectl get pods pod-first --show-labels 
 
 It is shown as follows , The label is successful  
NAME        READY   STATUS    RESTARTS   AGE    LABELS
pod-first   1/1     Running   0          139m   release=v1

View resource tags

# View all under the default namespace  pod  Tags for resources  
[[email protected] pp]# kubectl get pods --show-labels
NAME                          READY   STATUS    RESTARTS   AGE     LABELS
nginx-f89759699-tc62k         1/1     Running   2          4d20h   app=nginx,pod-template-hash=f89759699
nginx-test-84b997bfc5-6vccl   1/1     Running   0          16h     app=nginx,pod-template-hash=84b997bfc5
nginx-test-84b997bfc5-z6lqm   1/1     Running   0          16h     app=nginx,pod-template-hash=84b997bfc5
pod-first                     1/1     Running   0          140m    release=v1

# View the name specified under the default namespace  pod  All labels with  
[[email protected] pp]# kubectl get pods pod-first --show-labels
NAME        READY   STATUS    RESTARTS   AGE    LABELS
pod-first   1/1     Running   0          141m   release=v1
 
# Lists the labels under the default namespace  key  yes  release  Of  pod, Do not display labels  
[[email protected] pp]# kubectl get pods -l release
NAME        READY   STATUS    RESTARTS   AGE
pod-first   1/1     Running   0          141m

# Lists the labels under the default namespace  key  yes  release、 The value is  v1  Of  pod, Do not display labels  
[[email protected] pp]# kubectl get pods -l release=v1
NAME        READY   STATUS    RESTARTS   AGE
pod-first   1/1     Running   0          142m

# Lists the labels under the default namespace  key  yes  release  All of the  pod, And print the corresponding label value  key As a column  value Displayed in this column .
[[email protected] pp]# kubectl get pods -L release
NAME                          READY   STATUS    RESTARTS   AGE     RELEASE
nginx-f89759699-tc62k         1/1     Running   2          4d20h   
nginx-test-84b997bfc5-6vccl   1/1     Running   0          16h     
nginx-test-84b997bfc5-z6lqm   1/1     Running   0          16h     
pod-first                     1/1     Running   0          142m    v1
 
# View all under all namespaces  pod  The label of  
[[email protected] pp]# kubectl get pods --all-namespaces --show-labels 

# To have release Labeled pod Display and display the corresponding key and value
[[email protected] pp]# kubectl get pods -l release=v1 -L release 
NAME        READY   STATUS    RESTARTS   AGE    RELEASE
pod-first   1/1     Running   0          145m   v1

At the end

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