[FIXED] Spring boot docker Exception in thread "main" java.lang.NoClassDefFoundError: org/springframework/boot/SpringApplication

Issue

I want to start my spring-boot application in docker an i got an error in docker run

My Main-Class:

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

My pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>com.emo.test</groupId>
        <artifactId>test</artifactId>
        <version>0.1-SNAPSHOT</version>
    </parent>

    <artifactId>test-core</artifactId>
    <version>${parent.version}</version>
    <packaging>jar</packaging>

    <name>test-core</name>
    <url>http://maven.apache.org</url>

    <dependencies>
        ....
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <!-- Build an executable JAR -->
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <classpathPrefix>lib/</classpathPrefix>
                            <mainClass>com.test.Application</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

My manifest:

Manifest-Version: 1.0
Built-By: emo.leumassi
Build-Jdk: 11.0.7
Main-Class: com.test.Application
Created-By: Apache Maven

For some reasons, i don't want to use the spring-boot-maven-plugin

My Dockerfile

FROM openjdk:8-jdk-alpine
ARG JAR_FILE=test-*.jar
COPY ${JAR_FILE} test.jar
ENTRYPOINT ["java", "-jar", "test.jar"]

I created the container with this script:

docker build -t test .

docker run -p 8080:8080 test

I get this error:

Sending build context to Docker daemon  18.94kB
Step 1/4 : FROM openjdk:8-jdk-alpine
 ---> a3562aa0b991
Step 2/4 : ARG JAR_FILE=test-*.jar
 ---> Running in 739ab5566b9f
Removing intermediate container 739ab5566b9f
 ---> 9d2e5a894070
Step 3/4 : COPY ${JAR_FILE} test.jar
 ---> 2746354c80a5
Step 4/4 : ENTRYPOINT ["java", "-jar", "test.jar"]
 ---> Running in 9850a06d6686
Removing intermediate container 9850a06d6686
 ---> e5ec33eac8a9
Successfully built e5ec33eac8a9
Successfully tagged kazi-core:latest
Exception in thread "main" java.lang.NoClassDefFoundError: org/springframework/boot/SpringApplication
        at com.test.Application.main(Application.java:10)
Caused by: java.lang.ClassNotFoundException: org.springframework.boot.SpringApplication
        at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:349)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        ... 1 more

Solution

with spring boot we can use spring-boot-maven-plugin

 <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                        <configuration>
                            <classifier>exec</classifier>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

Answered By - emoleumassi
Answer Checked By - Dawn Plyler (JavaFixing Volunteer)