[ADD] - added files to build and dockerize a java application

.github/workflows/build-java-image.yaml

@@ -0,0 +1,84 @@
+name: Build & Push Java App
+
+on:
+  pull_request:
+    branches: [main]
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+env:
+  IMAGE_NAME: techiescamp/java-image
+  DOCKERFILE: ./Dockerfile
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Java 17 and Maven cache
+        uses: actions/setup-java@v5
+        with:
+          distribution: temurin
+          java-version: "21"
+          cache: maven
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Build with Maven (tests on)
+        working-directory: ./java-app
+        run: ./mvnw clean package
+
+      - name: Lint Dockerfile (hadolint)
+        if: ${{ github.event_name == 'pull_request' }}
+        uses: hadolint/hadolint-action@v3.1.0
+        with:
+          dockerfile: ${{ env.DOCKERFILE }}
+          failure-threshold: error
+
+      - name: Docker build (no push) for PR
+        if: ${{ github.event_name == 'pull_request' }}
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ${{ env.DOCKERFILE }}
+          platforms: linux/amd64
+          tags: ${{ env.IMAGE_NAME }}:pr-${{ github.event.number }}
+          load: true
+          push: false
+
+      - name: Trivy scan (image)
+        if: ${{ github.event_name == 'pull_request' }}
+        uses: aquasecurity/trivy-action@0.28.0
+        with:
+          scan-type: image
+          image-ref: ${{ env.IMAGE_NAME }}:pr-${{ github.event.number }}
+          severity: HIGH,CRITICAL
+          ignore-unfixed: true
+          format: table
+          exit-code: '0'
+
+      - name: Login to Docker Hub
+        if: ${{ github.event_name == 'push' }}
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_PASSWORD }}
+
+      - name: Docker build & push (multi-arch)
+        if: ${{ github.event_name == 'push' }}
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: ${{ env.DOCKERFILE }}
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: |
+            ${{ env.IMAGE_NAME }}:1.0.${{ github.run_number }}
+            ${{ env.IMAGE_NAME }}:latest

.gitignore

@@ -0,0 +1,30 @@
+.gradle/
+build/
+!gradle/wrapper/gradle-wrapper.jar
+
+target/
+!mvnw
+!mvnw.cmd
+.mvn/wrapper/maven-wrapper.jar
+
+.idea/
+*.iml
+
+.classpath
+.project
+.settings/
+
+.DS_Store
+Thumbs.db
+
+*.log
+*.tmp
+*.bak
+*.swp
+
+*.class
+
+*.war
+*.jar
+application-*.properties
+application-*.yml

Dockerfile

@@ -0,0 +1,14 @@
+# Use the distroless Java base image
+FROM gcr.io/distroless/java21-debian12
+
+# Set the working directory in the container
+WORKDIR /app
+
+# Copy the JAR file into the container at /app
+COPY java-app/target/*.jar java.jar
+
+# Expose the port your app runs on
+EXPOSE 8080
+
+# Run the jar file
+CMD ["java.jar"]

java-app/.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,4 @@
+# Maven to use
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.9/apache-maven-3.9.9-bin.zip
+# Wrapper bootstrap JAR to download when missing
+wrapperUrl=https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/3.3.2/maven-wrapper-3.3.2.jar

java-app/mvnw

@@ -0,0 +1,53 @@
+#!/bin/sh
+set -e
+
+# Resolve script dir
+PRG="$0"
+while [ -h "$PRG" ]; do
+  ls=$(ls -ld "$PRG"); link=$(expr "$ls" : '.*-> \(.*\)$')
+  if expr "$link" : '/.*' >/dev/null; then PRG="$link"; else PRG=$(dirname "$PRG")"/$link"; fi
+done
+BASEDIR=$(cd "$(dirname "$PRG")" >/dev/null 2>&1 && pwd -P)
+APP_HOME="$BASEDIR"
+
+WRAPPER_DIR="$APP_HOME/.mvn/wrapper"
+WRAPPER_JAR="$WRAPPER_DIR/maven-wrapper.jar"
+WRAPPER_PROPS="$WRAPPER_DIR/maven-wrapper.properties"
+
+# Pick Java
+if [ -n "$JAVA_HOME" ]; then JAVA_CMD="$JAVA_HOME/bin/java"; else JAVA_CMD="java"; fi
+
+# Find project base dir (folder that has pom.xml)
+if [ -z "$MAVEN_PROJECTBASEDIR" ]; then
+  CUR="$APP_HOME"
+  while [ "$CUR" != "/" ]; do
+    if [ -f "$CUR/pom.xml" ]; then MAVEN_PROJECTBASEDIR="$CUR"; break; fi
+    CUR=$(cd "$CUR/.." && pwd -P)
+  done
+  [ -n "$MAVEN_PROJECTBASEDIR" ] || MAVEN_PROJECTBASEDIR="$APP_HOME"
+fi
+
+# Download wrapper JAR if missing
+if [ ! -f "$WRAPPER_JAR" ]; then
+  mkdir -p "$WRAPPER_DIR"
+  if [ ! -f "$WRAPPER_PROPS" ]; then
+    echo "Missing $WRAPPER_PROPS" >&2; exit 1
+  fi
+  WRAPPER_URL=$(grep -E '^wrapperUrl=' "$WRAPPER_PROPS" | cut -d'=' -f2-)
+  if [ -z "$WRAPPER_URL" ]; then
+    echo "wrapperUrl not found in $WRAPPER_PROPS" >&2; exit 1
+  fi
+  echo "Downloading Maven Wrapper JAR from $WRAPPER_URL ..."
+  if command -v curl >/dev/null 2>&1; then
+    curl -fsSL -o "$WRAPPER_JAR" "$WRAPPER_URL"
+  elif command -v wget >/dev/null 2>&1; then
+    wget -q -O "$WRAPPER_JAR" "$WRAPPER_URL"
+  else
+    echo "Need curl or wget to download maven-wrapper.jar" >&2; exit 1
+  fi
+fi
+
+exec "$JAVA_CMD" \
+  -Dmaven.wrapper.log.level=INFO \
+  "-Dmaven.multiModuleProjectDirectory=$MAVEN_PROJECTBASEDIR" \
+  -cp "$WRAPPER_JAR" org.apache.maven.wrapper.MavenWrapperMain "$@"

java-app/mvnw.cmd

@@ -0,0 +1,46 @@
+@ECHO OFF
+SETLOCAL
+
+SET "BASEDIR=%~dp0"
+SET "WRAPPER_DIR=%BASEDIR%.mvn\wrapper"
+SET "WRAPPER_JAR=%WRAPPER_DIR%\maven-wrapper.jar"
+SET "WRAPPER_PROPS=%WRAPPER_DIR%\maven-wrapper.properties"
+
+IF EXIST "%JAVA_HOME%\bin\java.exe" (
+  SET "JAVA_EXE=%JAVA_HOME%\bin\java.exe"
+) ELSE (
+  SET "JAVA_EXE=java"
+)
+
+IF NOT EXIST "%WRAPPER_JAR%" (
+  IF NOT EXIST "%WRAPPER_DIR%" MKDIR "%WRAPPER_DIR%"
+  FOR /F "usebackq tokens=1,2 delims==" %%A IN ("%WRAPPER_PROPS%") DO (
+    IF "%%A"=="wrapperUrl" SET "WRAPPER_URL=%%B"
+  )
+  IF "%WRAPPER_URL%"=="" (
+    ECHO wrapperUrl not found in %WRAPPER_PROPS%
+    EXIT /B 1
+  )
+  ECHO Downloading Maven Wrapper JAR from %WRAPPER_URL%
+  POWERSHELL -NoProfile -ExecutionPolicy Bypass -Command ^
+    "Invoke-WebRequest -Uri '%WRAPPER_URL%' -OutFile '%WRAPPER_JAR%'"
+)
+
+REM Find project base dir
+SET "MAVEN_PROJECTBASEDIR="
+SET "CUR=%CD%"
+:findPom
+IF EXIST "%CUR%\pom.xml" (
+  SET "MAVEN_PROJECTBASEDIR=%CUR%"
+) ELSE (
+  CD /D "%CUR%\.."
+  SET "CUR=%CD%"
+  IF "%CUR%"=="%SystemDrive%\" GOTO afterFind
+  GOTO findPom
+)
+:afterFind
+IF "%MAVEN_PROJECTBASEDIR%"=="" SET "MAVEN_PROJECTBASEDIR=%BASEDIR%"
+
+"%JAVA_EXE%" -Dmaven.wrapper.log.level=INFO ^
+ "-Dmaven.multiModuleProjectDirectory=%MAVEN_PROJECTBASEDIR%" ^
+ -cp "%WRAPPER_JAR%" org.apache.maven.wrapper.MavenWrapperMain %*

java-app/pom.xml

@@ -0,0 +1,52 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <groupId>org.springframework.boot</groupId>
+    <artifactId>spring-boot-starter-parent</artifactId>
+    <version>3.3.4</version>
+    <relativePath/>
+  </parent>
+
+  <groupId>com.techiescamp</groupId>
+  <artifactId>java-app</artifactId>
+  <version>1.0.0</version>
+  <name>java-app</name>
+  <description>Spring Boot application</description>
+
+  <properties>
+    <java.version>21</java.version>
+  </properties>
+
+  <dependencies>
+    <!-- Core -->
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter</artifactId>
+    </dependency>
+
+    <!-- Web API (remove if not needed) -->
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-web</artifactId>
+    </dependency>
+
+    <!-- Tests -->
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-test</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-maven-plugin</artifactId>
+      </plugin>
+    </plugins>
+  </build>
+</project>

java-app/src/main/java/springboot/Application.java

@@ -0,0 +1,20 @@
+package springboot;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@SpringBootApplication
+@RestController
+public class Application {
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+
+    @GetMapping("/")
+    public String index() {
+        return "This is a demo Spring Boot application";
+    }
+}

java-app/src/test/java/springboot/ApplicationTest.java

@@ -0,0 +1,26 @@
+package springboot;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.web.servlet.MockMvc;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+@SpringBootTest
+@AutoConfigureMockMvc
+public class ApplicationTest {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    @Test
+    public void indexEndpointReturnsExpectedMessage() throws Exception {
+        mockMvc.perform(get("/"))
+                .andExpect(status().isOk())
+                .andExpect(content().string("This is a demo Spring Boot application"));
+    }
+}