Spring Boot 마이크로서비스를 Kubernetes 클러스터에 배포하기 (Github Actions 사용)

rootProject.name = 'kube-app'

plugins {
    id 'java'
    id 'org.springframework.boot' version '3.2.1'
    id 'io.spring.dependency-management' version '1.1.4'
}

group = 'com.yourcompany'
version = '1.0'

java {
    sourceCompatibility = '21'
}

repositories {
    mavenCentral()
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-web'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
}

./gradlew build

./gradlew bootRun

package com.yourcompany.kubeapp.post;

public record Post(Integer id, String title, String content) {
}

package com.yourcompany.kubeapp.post;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;
import java.util.stream.IntStream;

@RestController
public class PostController {

    private final TextPopulator populator;

    public PostController(TextPopulator populator) {
        this.populator = populator;
    }

    @GetMapping("/")
    public String helloWorld() {
        return "Hello World";
    }

    @GetMapping("/posts")
    public List<Post> listPosts() {
        return IntStream.rangeClosed(1, 20)
                .mapToObj(this::createPost)
                .toList();
    }

    private Post createPost(int id) {
        String title = populator.randomTitle();
        String content = String.format("%s %s", populator.randomContent(), populator.randomContent());
        return new Post(id, title, content);
    }
}

FROM openjdk:21-slim
WORKDIR /app
COPY build/libs/kube-app-1.0.jar app.jar
EXPOSE 8080

ENTRYPOINT ["java", "-jar", "app.jar"]

COPY build/libs/<your-app-name>-<version>.jar app.jar

docker build -t kube-app .

docker run -p 8080:8080 kube-app

kubectl create secret docker-registry my-docker-registry \
  --docker-server=ghcr.io \
  --docker-username=DEPLOYMENT_TOKEN \
  --docker-password=TOKEN_VALUE

spec:
  containers:
  - name: kube-app
    image: ghcr.io/mustafaguc/kube-app:latest
  imagePullSecrets:
  - name: my-docker-registry

kubectl config view --minify --raw > kubeconfig.yaml

# 배포 설정
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: kube-app
  name: kube-app
  namespace: default
spec:
  selector:
    matchLabels:
      app: kube-app
  template:
    metadata:
      labels:
        app: kube-app
      name: kube-app
      namespace: default
    spec:
      containers:
        - image: ghcr.io/mustafaguc/kube-app:latest
          imagePullPolicy: Always
          name: container-0
          ports:
            - containerPort: 8080
              name: http
              protocol: TCP
          resources: {}
      dnsPolicy: ClusterFirst
      imagePullSecrets:
        - name: my-docker-registry
      restartPolicy: Always


# 서비스 설정
---
apiVersion: v1
kind: Service
metadata:
  name: kube-app
  namespace: default
spec:
  ports:
    - name: http
      port: 80
      protocol: TCP
      targetPort: 8080
  selector:
    app: kube-app
  sessionAffinity: None
  type: ClusterIP


# 인그레스 설정
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: kube-app
  namespace: default
spec:
  ingressClassName: nginx
  rules:
    - host: kube-app.example.com
      http:
        paths:
          - backend:
              service:
                name: kube-app
                port:
                  name: http
            path: /
            pathType: Prefix

# 이 워크플로우는 Gradle을 사용하여 Java 프로젝트를 빌드하고, 종속성을 캐시/복원하여 워크플로우 실행 시간을 개선합니다.
# 자세한 내용은 https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-java-with-gradle 를 참조하세요.

name: Java Gradle Build & Docker Push

on:
  push:
    branches: [ "main" ]
  pull_request:
    branches: [ "main" ]

env:
  # 비어 있을 경우 Docker Hub용 docker.io 사용
  REGISTRY: ghcr.io
  # github.repository를 <account>/<repo>로 사용
  IMAGE_NAME: ${{ github.repository }}

jobs:
  build:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
      id-token: write

    steps:
    - uses: actions/checkout@v3
    - name: Set up JDK 21
      uses: actions/setup-java@v3
      with:
        java-version: '21'
        distribution: 'temurin'
    - name: Build with Gradle
      uses: gradle/gradle-build-action@bd5760595778326ba7f1441bcf7e88b49de61a25 # v2.6.0
      with:
        arguments: build

    - name: Install cosign
      if: github.event_name != 'pull_request'
      uses: sigstore/cosign-installer@6e04d228eb30da1757ee4e1dd75a0ec73a653e06 #v3.1.1
      with:
        cosign-release: 'v2.1.1'

    - name: Set up Docker Buildx
      uses: docker/setup-buildx-action@f95db51fddba0c2d1ec667646a06c2ce06100226 # v3.0.0

    - name: Log into registry ${{ env.REGISTRY }}
      if: github.event_name != 'pull_request'
      uses: docker/login-action@343f7c4344506bcbf9b4de18042ae17996df046d # v3.0.0
      with:
        registry: ${{ env.REGISTRY }}
        username: ${{ github.actor }}
        password: ${{ secrets.GITHUB_TOKEN }}

    - name: Extract Docker metadata
      id: meta
      uses: docker/metadata-action@96383f45573cb7f253c731d3b3ab81c87ef81934 # v5.0.0
      with:
        images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}

    - name: Build and push Docker image
      id: build-and-push
      uses: docker/build-push-action@0565240e2d4ab88bba5387d719585280857ece09 # v5.0.0
      with:
        context: .
        push: ${{ github.event_name != 'pull_request' }}
        tags: |
          ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
          ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ github.sha }}
        labels: ${{ steps.meta.outputs.labels }}
        cache-from: type=gha
        cache-to: type=gha,mode=max

  deploy:
    name: Deploy
    needs: [ build ]
    runs-on: ubuntu-latest
    steps:
      - name: Set the Kubernetes context
        uses: azure/k8s-set-context@v3
        with:
          method: kubeconfig
          kubeconfig: ${{ secrets.KUBECONFIG }}

      - name: Checkout source code
        uses: actions/checkout@v3

      - name: Deploy to the Kubernetes cluster
        uses: azure/k8s-deploy@v4
        with:
          skip-tls-verify: true
          manifests: |
            kubernetes/project.yaml
          images: |
            ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ github.sha }}