เขียน Pipeline ใน Jenkins สำหรับ Kubernetes

ขอบคุณรูปภาพจาก https://www.weave.works

บทความนี้ ผมขอข้ามการอธิบาย Docker และ Kubernetes ว่าคืออะไร ทำงานอย่างไร แต่จะ Focus ไปที่การ Setup Jenkins เพื่อ Deploy เท่านั้น

Jenkins

Jenkins คือ เครื่องมือที่ช่วยให้การ Deployment สะดวก รวดเร็ว และง่ายขึ้นใน One click ซึ่งเรียกว่า CI/CD นั่นเอง ในปัจจุบันก็มีหลายตัวมากๆ แต่ตัวที่ได้รับความนิยมนั้นมีไม่กี่ตัว และ Jenkins ก็เป็นหนึ่งในนั้นครับ โดยปกติแล้วการ Deploy เราจะ Manual build เองแล้วนำไฟล์ต่างๆไปวางใน Server ทำเองทุกอย่างทีล่ะขั้นตอน และทำแบบเดิมซ้ำๆทุกครั้งที่มีการ Deploy ในหลายๆโปรเจค นั่นแหล่ะครับ มันก็คงจะดีกว่าถ้าแต่ล่ะโปรเจคสามารถ Deploy ได้ด้วยเพียงแค่ One click และการ Config Jenkins นั้นก็สามารถทำได้หลายวิธีจนไปถึงสามารถเขียน Script เองได้ที่เรียกกันว่า Pipeline นั่นเอง

. . .

Prerequire

Java 11 or 17
Jenkins (Require Java)
- Mac OS - brew install jenkins-lts (Install ผ่าน Homebrew)
- Windows - Download Jenkins (เลือก Windows)
- Linux - Install Jenkins
Docker
minikube (Require Docker)
kubectl
Spring-Boot Application (Source Code)

. . .

Solution Overview

Pull code ล่าสุดจาก Github เมื่อเราสั่ง Build
Build .jar ด้วย Maven
Build docker image ด้วย Dockerfile ที่อยู่ในโปรเจค
Push docker image ไปยัง Docker Hub (คล้าย Github แต่ใช้เก็บ Docker image)
Deploy Kubernetes ด้วย Kubeconfig ที่เรากำหนดไว้ โดย Kubernetes จะไปเอา Docker image จาก Docker Hub ตาม Tag ที่เรากำหนดไว้มา Deploy

ถ้าเราไม่มี Jenkins เราจะต้องทำ 5 ขั้นตอนนี้แบบ Manual เองทุกๆครั้งที่ Deploy

. . .

Start Jenkins

Mac OS (Method 1: Install Jenkins Using the Homebrew Package Manager)
Linux (Start Jenkins)
Windows

. . .

Setup Jenkins (First Time)

เข้า Jenkins UI ด้วย http://localhost:8080 (Default)
cat /Users/[user]/.jenkins/secrets/initialAdminPassword แล้วจะได้ secret ออกมาเอามาใส่ Administrator password
เลือก Install suggested plugins รอจนเสร็จ
กรอก Username กำหนด Password และตั้งชื่อ
เลือก Save and Continue > Save and Finish > Start using Jenkins

. . .

Install Plugins

เข้าไปที่ Dashboard > Manage Jenkins > Plugins > Advanced settings
Download File (Kubernetes Continuous Deploy PluginVersion1.0.0)
เลือนไปที่ Deploy Plugin แล้วเลือก Choose File เพื่อ Upload Plugin ที่ Download มา
เลือก Deploy รอจนเสร็จ

. . .

Setup Credentials

เข้าไปที่ Dashboard > Manage Jenkins > Credentials > System > Global credentials (unrestricted) เลือก + Add Credentilas

Kubeconfig

กำหนด ID และ Description เป็น k8sconfigpwd

ใช้คำสั่ง open .kube/config (ต้อง Start Minikube ก่อน minikube start) จะเป็นการเปิด Config ขึ้นมาใน Text ให้ Copy เนื้อหาทั้งหมดในไฟล์มา ให้เอามาใส่ใน Content แล้วเลือก Create

Docker Hub

. . .

Setup Maven

Spring-Boot Application ของผมต้องใช้ Maven ในการ Build ไม่จำเป็นต้องมีในเครื่อง เราจะใช้ Maven ของ Jenkins เอา

ไปที่ "Dashboard > Manage Jenkins > Tools" เลื่อนลงไปที่ Maven installations

. . .

File Require in Spring-Boot Application

/k8s/deployment.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: discovery-service-app
  labels:
    app: discovery-service-app
spec:
  selector:
    matchLabels:
      app: discovery-service-app
  replicas: 2
  minReadySeconds: 15
  strategy:
    type: RollingUpdate                                   
    rollingUpdate: 
      maxUnavailable: 1                                   
      maxSurge: 1
  template:
    metadata:
      labels:
        app: discovery-service-app
    spec:
      containers:
        - name: discovery-service-app
          image: janescience/discovery-service:latest
          imagePullPolicy: Always
          ports:
            - containerPort: 9001

/k8s/service.yml

apiVersion: v1
kind: Service
metadata:
  name: discovery-svc
spec:
  type : LoadBalancer
  ports:
    - port: 80
      targetPort: 9001
      protocol: TCP
  selector:
    app: discovery-service-app

Dockerfile

FROM openjdk:17-jdk
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} discovery.jar
ENTRYPOINT ["java","-jar","discovery.jar"]
EXPOSE 9001

. . .

Jenkins Pipeline

เลือก "Dashboard > + New Item"
ตั้งชื่อ และเลือก Pipeline
เลื่อนลงมาที่ Pipeline เลือก Pipeline script แล้วเขียน Pipeline ลงไปใน Script ตามนี้

pipeline {
    agent any
    tools{
        maven 'maven_3_5_0'
    }
    environment {
        DOCKER_HOME = '/usr/local/bin/docker'  // Path to the Docker executable
    }
    stages{
        stage('Build Maven'){
            steps{
                checkout([$class: 'GitSCM', branches: [[name: '*/master']], extensions: [], userRemoteConfigs: [[url: 'https://github.com/Janescience/discovery-service']]])
                sh 'mvn clean install'
            }
        }
        stage('Build image'){
            steps{
                script{
                    sh '${DOCKER_HOME} build -t discovery-service:latest .'
                }
            }
        }
        
        stage('Push image to Hub'){
            steps{
                script{
                    withCredentials([usernamePassword(credentialsId: 'dockerhub-pwd', usernameVariable: 'DOCKER_USERNAME', passwordVariable: 'DOCKER_PASSWORD')]) {
                        sh '${DOCKER_HOME} login -u ${DOCKER_USERNAME} -p ${DOCKER_PASSWORD}'
                        sh '${DOCKER_HOME} tag discovery-service:latest janescience/discovery-service:latest'
                        sh '${DOCKER_HOME} push janescience/discovery-service:latest'
                        sh '${DOCKER_HOME} rmi -f $(${DOCKER_HOME} images -f "dangling=true" -q)'
                    }
                }
            }
        }
        stage('Deploy to k8s'){
            steps{
                script{
                    kubernetesDeploy (configs: 'k8s/deployment.yml',kubeconfigId: 'k8sconfigpwd')
                    kubernetesDeploy (configs: 'k8s/service.yml',kubeconfigId: 'k8sconfigpwd')
                }
            }
        
        }
    }
}

หรืออีกวิธีคือเลือก Pipeline script from SCM

เป็นการเก็บ Script Pipeline ไว้ใน Project แทน โดยตั้งชื่อไฟล์ว่า Jenkinsfile

และไปเพิ่ม Github Credentials เหมือน Setup Credentials เพื่อให้ Jenkins เข้าถึง Github ได้

. . .

Deploy to Kubernetes

เลือก Project และกด Build Now ถ้า Deploy สำเร็จต้องขึ้นสีเขียวหมดแบบนี้ (ต้อง Start minikube ก่อน)

ถ้าอยากดู Logs ดูได้ที่ "Permalinks > Last build > Console Output"

. . .

Verify Kubernetes Deployed


~ kubectl get all

NAME                                         READY   STATUS    RESTARTS      AGE
pod/discovery-service-app-6747dd94f9-5bsxs   1/1     Running   0             18m
pod/discovery-service-app-6747dd94f9-w6dhb   1/1     Running   0             18m


NAME                    TYPE           CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
service/discovery-svc   LoadBalancer   10.111.56.231    <pending>     80:31604/TCP   18m
service/kubernetes      ClusterIP      10.96.0.1        <none>        443/TCP        19h

NAME                                    READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/discovery-service-app   2/2     2            2           18m

NAME                                               DESIRED   CURRENT   READY   AGE
replicaset.apps/discovery-service-app-6747dd94f9   2         2         2       18m

ใน minikube จะไม่ Support EXTERNAL-IP แต่ถ้าเป็น Kubernetes ของ Cloud Provider เช่น Azure , GCP หรือ AWS ถึงจะมี Public IP เราต้องใช้คำสั่ง minikube service discovery-svc


~ minikube service discovery-svc

|-----------|---------------|-------------|---------------------------|
| NAMESPACE |     NAME      | TARGET PORT |            URL            |
|-----------|---------------|-------------|---------------------------|
| default   | discovery-svc |          80 | http://192.168.49.2:31605 |
|-----------|---------------|-------------|---------------------------|
🏃  Starting tunnel for service discovery-svc.
|-----------|---------------|-------------|------------------------|
| NAMESPACE |     NAME      | TARGET PORT |          URL           |
|-----------|---------------|-------------|------------------------|
| default   | discovery-svc |             | http://127.0.0.1:51232 |
|-----------|---------------|-------------|------------------------|
🎉  Opening service default/discovery-svc in default browser...
❗  Because you are using a Docker driver on darwin, the terminal needs to be open to run it.

เมื่อใช้คำสั่งนี้จะทำการเปิด Browser ให้อัตโนมัติ และเข้าไปที่ http://127.0.0.1:51232

. . .

Load Balance Test

ผมลอง Deploy อีกโปรเจคโดยทำเหมือนกันทุกอย่าง แล้วลอง Request ไปเยอะๆ และมีการ Log เอาไว้ โดยกำหนดเอาไว้ 2 Pods

อันนี้ Pod 1


~ kubectl logs -f pod/search-service-app-5745756985-xgsgk

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v3.1.0)

2023-10-29T08:42:27.260Z  INFO 1 --- [           main] c.spring.microservice.SearchApplication  : Starting SearchApplication v0.0.1 using Java 17.0.2 with PID 1 (/search.jar started by root in /)
2023-10-29T08:42:27.261Z  INFO 1 --- [           main] c.spring.microservice.SearchApplication  : No active profile set, falling back to 1 default profile: "default"
2023-10-29T08:42:28.007Z  INFO 1 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data JPA repositories in DEFAULT mode.
2023-10-29T08:42:28.067Z  INFO 1 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 35 ms. Found 5 JPA repository interfaces.
2023-10-29T08:42:28.449Z  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8086 (http)
2023-10-29T08:42:28.453Z  INFO 1 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-10-29T08:42:28.454Z  INFO 1 --- [           main] o.apache.catalina.core.StandardEngine    : Starting Servlet engine: [Apache Tomcat/10.1.8]
2023-10-29T08:42:28.504Z  INFO 1 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-10-29T08:42:28.505Z  INFO 1 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1206 ms
2023-10-29T08:42:28.754Z  INFO 1 --- [           main] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [name: default]
2023-10-29T08:42:28.790Z  INFO 1 --- [           main] org.hibernate.Version                    : HHH000412: Hibernate ORM core version 6.2.2.Final
2023-10-29T08:42:28.791Z  INFO 1 --- [           main] org.hibernate.cfg.Environment            : HHH000406: Using bytecode reflection optimizer
2023-10-29T08:42:28.883Z  INFO 1 --- [           main] o.h.b.i.BytecodeProviderInitiator        : HHH000021: Bytecode provider name : bytebuddy
2023-10-29T08:42:28.980Z  INFO 1 --- [           main] o.s.o.j.p.SpringPersistenceUnitInfo      : No LoadTimeWeaver setup: ignoring JPA class transformer
2023-10-29T08:42:28.989Z  INFO 1 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2023-10-29T08:42:29.462Z  INFO 1 --- [           main] com.zaxxer.hikari.pool.HikariPool        : HikariPool-1 - Added connection org.postgresql.jdbc.PgConnection@69c93ca4
2023-10-29T08:42:29.463Z  INFO 1 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
2023-10-29T08:42:29.525Z  INFO 1 --- [           main] org.hibernate.orm.dialect                : HHH035001: Using dialect: org.hibernate.dialect.PostgreSQLDialect, version: org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$DialectResolutionInfoImpl@26f96b85
2023-10-29T08:42:30.152Z  INFO 1 --- [           main] o.h.b.i.BytecodeProviderInitiator        : HHH000021: Bytecode provider name : bytebuddy
2023-10-29T08:42:31.363Z  INFO 1 --- [           main] o.h.e.t.j.p.i.JtaPlatformInitiator       : HHH000490: Using JtaPlatform implementation: [org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform]
2023-10-29T08:42:31.823Z  INFO 1 --- [           main] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'
2023-10-29T08:42:32.350Z  INFO 1 --- [           main] o.s.d.j.r.query.QueryEnhancerFactory     : Hibernate is in classpath; If applicable, HQL parser will be used.
2023-10-29T08:42:32.663Z  WARN 1 --- [           main] JpaBaseConfiguration$JpaWebConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning
2023-10-29T08:42:33.865Z  INFO 1 --- [           main] o.s.b.a.e.web.EndpointLinksResolver      : Exposing 4 endpoint(s) beneath base path '/actuator'
2023-10-29T08:42:34.167Z  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8086 (http) with context path ''
2023-10-29T08:42:34.237Z  INFO 1 --- [           main] c.spring.microservice.SearchApplication  : Started SearchApplication in 7.265 seconds (process running for 7.685)
2023-10-29T08:59:16.311Z  INFO 1 --- [nio-8086-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2023-10-29T08:59:16.313Z  INFO 1 --- [nio-8086-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2023-10-29T08:59:16.320Z  INFO 1 --- [nio-8086-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 6 ms
2023-10-29T08:59:22.606Z  INFO 1 --- [nio-8086-exec-2] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:00:25.681Z  INFO 1 --- [nio-8086-exec-4] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:00:34.175Z  INFO 1 --- [nio-8086-exec-5] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:00:35.148Z  INFO 1 --- [nio-8086-exec-6] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:04:09.307Z  INFO 1 --- [nio-8086-exec-8] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:04:11.206Z  INFO 1 --- [nio-8086-exec-9] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:04:12.177Z  INFO 1 --- [io-8086-exec-10] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:04:12.981Z  INFO 1 --- [nio-8086-exec-1] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:04:13.681Z  INFO 1 --- [nio-8086-exec-2] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:04:14.383Z  INFO 1 --- [nio-8086-exec-3] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:04:15.154Z  INFO 1 --- [nio-8086-exec-4] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:04:20.707Z  INFO 1 --- [nio-8086-exec-5] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:04:22.288Z  INFO 1 --- [nio-8086-exec-6] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:04:23.427Z  INFO 1 --- [nio-8086-exec-7] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED

อันนี้ Pod 2


~ kubectl logs -f pod/search-service-app-5745756985-xqxtw

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v3.1.0)

2023-10-29T08:42:30.958Z  INFO 1 --- [           main] c.spring.microservice.SearchApplication  : Starting SearchApplication v0.0.1 using Java 17.0.2 with PID 1 (/search.jar started by root in /)
2023-10-29T08:42:30.959Z  INFO 1 --- [           main] c.spring.microservice.SearchApplication  : No active profile set, falling back to 1 default profile: "default"
2023-10-29T08:42:32.132Z  INFO 1 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data JPA repositories in DEFAULT mode.
2023-10-29T08:42:32.251Z  INFO 1 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 112 ms. Found 5 JPA repository interfaces.
2023-10-29T08:42:33.741Z  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8086 (http)
2023-10-29T08:42:33.747Z  INFO 1 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-10-29T08:42:33.747Z  INFO 1 --- [           main] o.apache.catalina.core.StandardEngine    : Starting Servlet engine: [Apache Tomcat/10.1.8]
2023-10-29T08:42:33.863Z  INFO 1 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-10-29T08:42:33.925Z  INFO 1 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 2827 ms
2023-10-29T08:42:34.560Z  INFO 1 --- [           main] o.hibernate.jpa.internal.util.LogHelper  : HHH000204: Processing PersistenceUnitInfo [name: default]
2023-10-29T08:42:34.596Z  INFO 1 --- [           main] org.hibernate.Version                    : HHH000412: Hibernate ORM core version 6.2.2.Final
2023-10-29T08:42:34.597Z  INFO 1 --- [           main] org.hibernate.cfg.Environment            : HHH000406: Using bytecode reflection optimizer
2023-10-29T08:42:34.682Z  INFO 1 --- [           main] o.h.b.i.BytecodeProviderInitiator        : HHH000021: Bytecode provider name : bytebuddy
2023-10-29T08:42:34.768Z  INFO 1 --- [           main] o.s.o.j.p.SpringPersistenceUnitInfo      : No LoadTimeWeaver setup: ignoring JPA class transformer
2023-10-29T08:42:34.784Z  INFO 1 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2023-10-29T08:42:35.241Z  INFO 1 --- [           main] com.zaxxer.hikari.pool.HikariPool        : HikariPool-1 - Added connection org.postgresql.jdbc.PgConnection@69c93ca4
2023-10-29T08:42:35.243Z  INFO 1 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
2023-10-29T08:42:35.302Z  INFO 1 --- [           main] org.hibernate.orm.dialect                : HHH035001: Using dialect: org.hibernate.dialect.PostgreSQLDialect, version: org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$DialectResolutionInfoImpl@46d8f407
2023-10-29T08:42:35.503Z  INFO 1 --- [           main] o.h.b.i.BytecodeProviderInitiator        : HHH000021: Bytecode provider name : bytebuddy
2023-10-29T08:42:36.042Z  INFO 1 --- [           main] o.h.e.t.j.p.i.JtaPlatformInitiator       : HHH000490: Using JtaPlatform implementation: [org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform]
2023-10-29T08:42:36.295Z  INFO 1 --- [           main] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'
2023-10-29T08:42:36.491Z  INFO 1 --- [           main] o.s.d.j.r.query.QueryEnhancerFactory     : Hibernate is in classpath; If applicable, HQL parser will be used.
2023-10-29T08:42:36.668Z  WARN 1 --- [           main] JpaBaseConfiguration$JpaWebConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning
2023-10-29T08:42:37.041Z  INFO 1 --- [           main] o.s.b.a.e.web.EndpointLinksResolver      : Exposing 4 endpoint(s) beneath base path '/actuator'
2023-10-29T08:42:37.166Z  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8086 (http) with context path ''
2023-10-29T08:42:37.184Z  INFO 1 --- [           main] c.spring.microservice.SearchApplication  : Started SearchApplication in 6.817 seconds (process running for 7.657)
2023-10-29T08:45:38.147Z  INFO 1 --- [nio-8086-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
2023-10-29T08:45:38.149Z  INFO 1 --- [nio-8086-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
2023-10-29T08:45:38.156Z  INFO 1 --- [nio-8086-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 7 ms
2023-10-29T08:46:35.605Z  INFO 1 --- [nio-8086-exec-3] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
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2023-10-29T09:02:13.476Z  INFO 1 --- [io-8086-exec-10] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:02:20.416Z  INFO 1 --- [nio-8086-exec-1] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
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2023-10-29T09:02:27.088Z  INFO 1 --- [nio-8086-exec-7] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:02:27.824Z  INFO 1 --- [nio-8086-exec-8] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:02:28.707Z  INFO 1 --- [nio-8086-exec-9] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
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2023-10-29T09:03:01.956Z  INFO 1 --- [nio-8086-exec-7] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
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2023-10-29T09:03:03.150Z  INFO 1 --- [nio-8086-exec-9] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:03:03.604Z  INFO 1 --- [io-8086-exec-10] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:03:03.816Z  INFO 1 --- [nio-8086-exec-1] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:03:04.036Z  INFO 1 --- [nio-8086-exec-2] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:03:04.265Z  INFO 1 --- [nio-8086-exec-4] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:03:04.493Z  INFO 1 --- [nio-8086-exec-3] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED
2023-10-29T09:03:04.693Z  INFO 1 --- [nio-8086-exec-5] c.s.m.c.IndividualSearchController       : INDIVIDUAL SEARCH PROFILE CALLED

จะเห็นว่ามีการจัดการแบ่ง Request ให้อัตโนมัติ และถ้าอยากเข้าใจและศึกษาเพิ่มเติมเกี่ยวกับ Kubernetes มากกว่านี้ผมแนะนำบทความนี้ครับ Learn Kubernetes in Under 3 Hours: A Detailed Guide to Orchestrating Containers