First use of kubernetes cronjob

background

Although it has been used for several years kubernetes Yes . But the types of service applications are generally deployments statefuset daemonset Several types , as for job cronjob I haven't used it much . Now there's just one php The service of the application needs to be executed every five minutes , Just can go to know a ＣronJob Use ！

First, review it kubernetes Of workloads

reference ：https://kubernetes.io/zh/docs/concepts/workloads/

• Deployment and ReplicaSet （ Replace the original resource ReplicationController）. Deployment Ideal for managing stateless applications on your cluster ,Deployment All in Pod They are all equivalent to each other , And be replaced when needed .
• StatefulSet Allows you to run one or more of the Pods. for example , If your load will persist the data , You can run a StatefulSet, Each one Pod With someone PersistentVolume correspond . you are here StatefulSet In each Pod Code running in can copy data to the same StatefulSet Others in Pod In order to improve the overall service reliability .
• DaemonSet Define... That provides local support facilities for nodes Pods. these Pods Maybe the operation and maintenance of your cluster is Very important , For example, as an auxiliary tool for network links or as a network plug-in unit And so on . Every time you add a new node to the cluster , If the node is associated with DaemonSet Protocol matching of , Then the control surface will be the DaemonSet Dispatch a Pod Run on the new node .
• Job and CronJob. Define tasks that run to the end and stop .Job It's a one-time task , and CronJob It will run repeatedly according to its time plan .
• Third party workload resources , adopt Custom resource definition （CRD） Add third-party workload resources

Pods

Of course, the above workloads are ultimately managed by Pod, therefore Pod Where should I put it ？Pod Yes, you can. Kubernetes Created and managed in 、 The smallest deployable cell .Pod Similar to a set of shared namespace and file system volumes Docker Containers .

reference ：https://kubernetes.io/zh/docs/concepts/workloads/pods/

Cronjob For the first time

Define the needs

１. Mirror image 　php7.4 above 　 Need to install gd mysql rely on

２. Run every five minutes

Basic image construction

Because of me php Mirrors are nginx Packed together . And this application is a pure php application . I decided to rebuild an image , reference dockerhub:https://registry.hub.docker.com/_/php

Dockerfile

FROM php:7.4-fpm
RUN apt-get update && apt-get install -y \
        libfreetype6-dev \
        libjpeg62-turbo-dev \
        libpng-dev \
    && docker-php-ext-configure gd --with-freetype --with-jpeg \
    && docker-php-ext-install -j$(nproc) gd pdo_mysql mysqli

To overcome inertia , The working environment is switched to linux If the screenshot is not convenient, the figure above will not be displayed . The image warehouse uses the personal version of Tencent cloud tcr（ It seems that they were merged some time ago , It used to be a personal warehouse ）

Build a mirror image , And push the basic image to the basic warehouse ：

docker build -t ccr.ccs.tencentyun.com/laya-master/php:7.4-fpm .
docker push ccr.ccs.tencentyun.com/laya-master/php:7.4-fpm 

jenkins pipeline Pipeline construction

Pipeline reference ：https://duiniwukenaihe.blog.csdn.net/article/details/116661391

reference ：stage Single choice multiple choice problem

image.png

pipeline do when Judge

            when {
                environment name: 'XXXX', value: 'true'
            }

Add... Under the sub project folder Dockerfile

FROM ccr.ccs.tencentyun.com/xxxx/php:7.4-fpm
ADD html /var/www/html
WORKDIR /var/www/html[

notes : Because this is git A new sub file directory is added under the project. If it is not a new project, it will not be written completely pipeline Just add clips ！

１. Build and upload images to the image warehouse

        stage('docker build worldmap-job') {
            agent { label  "build" }
            when {
                environment name: 'worldmap-job', value: 'true'
            }
            steps {
                sh " cd worldmap-job&&docker build -t ccr.ccs.tencentyun.com/xxxx/worldmap-job:$data ."
                withCredentials([usernamePassword(credentialsId: 'xxxx', passwordVariable: 'dockerPassword', usernameVariable: 'dockerUser')]) {
                    sh "docker login -u ${dockerUser} -p ${dockerPassword} ccr.ccs.tencentyun.com"
                    sh "docker push ccr.ccs.tencentyun.com/xxxx/worldmap-job:$data"
        }             
            }
            }  

２. Deploy the application

                stage("develop worldmap-job") {
                    when {
                        environment name: 'worldmap-job', value: 'true'
                    }
                 
                    steps {
                        sh "sed -e 's/{data}/$data/g' /home/jenkins/workspace/yaml/develop/worldmap-job.tpl > /home/jenkins/workspace/yaml/develop/worldmap-job.yaml"
                        sh "sed -e 's/{data}/$data/g' /home/jenkins/workspace/yaml/develop/worldmap-job.tpl > /home/jenkins/workspace/yaml/develop/worldmap-job.yaml"
                              sh "sudo kubectl apply -f /home/jenkins/workspace/yaml/develop/worldmap-job.yaml --namespace=develop"
                              sh "sudo kubectl apply -f /home/jenkins/workspace/yaml/develop/worldmap-job.yaml --namespace=develop"
}
      }

Note that the format here may be different from that of ordinary users , Because the deployment here uses parallelism parallel . reference ：https://duiniwukenaihe.blog.csdn.net/article/details/116661391

tpl Template file

worldmap-job.tpl

apiVersion: batch/v1
kind: CronJob
metadata:
  name: worldmap-job
spec:
  schedule: "*/5 * * * *"
  jobTemplate:
    spec:
      template:      
        spec: 
          containers:
          - name: worldmap-job
            image: ccr.ccs.tencentyun.com/xxxx/worldmap-job:{data}
            imagePullPolicy: IfNotPresent
            args:
            - /usr/local/bin/php
            - /var/www/html/DrawLandsMap.php
            - run_job
            - "6"
            envFrom:
            - configMapRef:
                name: deploy
            env:
            - name: PHP_MEM_LIMIT
              value: "256M"
            resources:
              requests:
                memory: "256M"
                cpu: "250m"
              limits:
                memory: "1024M"
                cpu: "2000m" 
          imagePullSecrets:                                              
            - name: tencent
          restartPolicy: OnFailure

There are several points to pay attention to ：

schedule　　　schedule: "/5 * * *"　　###5 Once per minute

imagePullPolicy　　imagePullPolicy: IfNotPresent　　＃＃＃imagePullPolicy Self judgment seems to be three necessities , I copy deployments The configuration of the has been changed. At the beginning, it seems that there is a mistake

args　 Executing scripts is still 　 Numbers should be emphasized with quotation marks

envFrom　 I quote configmap The variables in the

env　 Limit php limit

sesources　 Made resource restrictions

imagePullSecrets　　 Mirror warehouse secret

restartPolicy 　 Container restart strategy

now jenkins Trigger a build . land kubernetes Cluster validation ：

[[email protected] develop]# kubectl get cronjob -n develop
NAME                SCHEDULE      SUSPEND   ACTIVE   LAST SCHEDULE   AGE
worldmap-job   */5 * * * *   False     0        2m36s           28h
[[email protected] develop]# kubectl get pods -n develop|grep world
worldmap-job-27357635-274hp           0/1     Completed   0          12m
worldmap-job-27357640-wb459           0/1     Completed   0          7m53s
worldmap-job-27357645-cndb4           0/1     Completed   0          2m53s
[[email protected] develop]# kubectl get jobs --watch -n develop
NAME                         COMPLETIONS   DURATION   AGE
worldmap-job-27357635   1/1           11s        13m
worldmap-job-27357640   1/1           11s        8m43s
worldmap-job-27357645   1/1           12s        3m43s

It seems like this , Only the latest reality ３ individual job Of course, those who are interested can study how to change the number of this ？(successfulJobsHistoryLimit: 3) k It can be modified . Checked it again pod Logs are normal . also job５ The minute trigger time is 0 5 10 In this order

Some of my own thoughts ：

1. cronjob Resource restriction
2. cronjob You can also mount configmap
3. Task type applications can try to apply job or cronjob
4. The image still needs to be rebuilt , Different applications . This reduces the size of the image , Reduce vulnerability possibilities