Issue using Dockerfile with Java and Maven as build tool

Question

I have an issue running a docker container. I am using Java 17 with Maven.

I have the following Dockerfile:

FROM maven:3.8.3-openjdk-17 as builder

WORKDIR /workdir
COPY pom.xml .
COPY src ./src


RUN mvn package -DskipTests


FROM openjdk:17.0-jdk-slim

COPY --from=builder /workdir/target/myproj-*.jar /myproj.jar


CMD ["java" , "-Djava.security.egd=file:/dev/./urandom", "-jar", "/myproj.jar"]

The below pom.xml file:

<?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>

  <groupId>com.myproj</groupId>
  <artifactId>myproj</artifactId>
  <version>1.0-SNAPSHOT</version>

  <name>myproj</name>

  <properties>
    <maven.compiler.source>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
        <groupId>com.hellokaton</groupId>
        <artifactId>blade-core</artifactId>
        <version>2.1.2.RELEASE</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <!-- Build an executable JAR -->
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-jar-plugin</artifactId>
        <version>3.1.0</version>
        <configuration>
          <archive>
            <manifest>
              <mainClass>com.myproj.App</mainClass>
            </manifest>
          </archive>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

And finally the below main class:

package com.myproj;

import java.io.IOException;

import com.hellokaton.blade.Blade;


public class App 
{
    public static void main(String[] args )
    {
        try {
            Blade blade = Blade.create();
            blade.start();
            
        } catch (IOException e) {
            
            e.printStackTrace();
        }

    }
}

When I run the below commands on docker:

docker build . --tag gcr.io/myproj-c39b9/myproj 
docker run -d -p 80:80 gcr.io/myproj-c39b9/myproj

I get this error

2023-02-08 08:19:58 Exception in thread "main" java.lang.NoClassDefFoundError: com/hellokaton/blade/Blade
2023-02-08 08:19:58 at com.myproj.App.main(App.java:14)
2023-02-08 08:19:58 Caused by: java.lang.ClassNotFoundException: com.hellokaton.blade.Blade
2023-02-08 08:19:58 at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
2023-02-08 08:19:58 at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
2023-02-08 08:19:58 at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
2023-02-08 08:19:58 ... 1 more

I am not sure what is missing here. I would guess it is something related to classpath setting.

I need your usual support please.

Thank you