Build executable jar in docker container using Maven

Question

How can I build an executable jar file in a docker container using Maven?

A simplified example of what I am trying to solve.

Local repo layout:

Main:

package org.example;

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello world!");
    }
}

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>

    <groupId>org.example</groupId>
    <artifactId>maven-troubleshooting</artifactId>
    <version>1.0-SNAPSHOT</version>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>3.3.0</version>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>org.example.Main</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

</project>

Local machine workflow(working as expected):

mvn clean package

...[INFO] BUILD SUCCESS

java -jar target/maven-troubleshooting-1.0-SNAPSHOT.jar

Hello world!

Dockerfile:

FROM maven:3.8.6-openjdk-11
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
COPY pom.xml /usr/src/app
COPY src /usr/src/app

Docker workflow:

docker build . -t simplified-mvn-troubleshooting
docker run -it simplified-mvn-troubleshooting bash

(now in the running container)

mvn clean package
...[INFO] BUILD SUCCESS

java -jar target/maven-troubleshooting-1.0-SNAPSHOT.jar

Error: Could not find or load main class org.example.Main
Caused by: java.lang.ClassNotFoundException: org.example.Main

What am I missing?

Did you mean to RUN mvn package in the Dockerfile? With what you've shown you're copying the source code but not building it at all. (Don't forget to also declare the main container CMD to launch the Java process as well.) — David Maze
– David Maze, Commented Dec 5, 2022 at 1:16
@ThorbjørnRavnAndersen I've shown this in the question description exactly. — pippa dupree
– pippa dupree, Commented Dec 5, 2022 at 7:38
@DavidMaze I'm running mvn package manually after attaching to the container as shown in the steps in the question description. — pippa dupree
– pippa dupree, Commented Dec 5, 2022 at 7:40

pippa dupree · Accepted Answer · 2022-12-05 15:36:33Z

3

I solved this after a few hours of trial and error. It appears Maven is pretty strict with directory structure. I changed my dockerfile to the below which solved the issue.

FROM maven:3.8.6-openjdk-11 AS build
COPY pom.xml .
COPY src /src

I can now package and run the jar all in the docker container directly after attaching to the container.

edited Dec 5, 2022 at 15:36

answered Dec 5, 2022 at 15:31

pippa dupree

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1 Comment

Thorbjørn Ravn Andersen Over a year ago

Next time, look inside the jar file to see what is there, and compare with the functional one. COPY . . is your friend.

Figurinha · Accepted Answer · 2025-08-21 15:27:15Z

I was able to define a Dockerfile that builds and run a maven application:

Used the following docker image:tags:

for building maven package and generating .jar file: maven:3.8.5-openjdk-17
for running jar file: openjdk:17-jdk-alpine

# BUILD
FROM maven:3.8.5-openjdk-17 AS build
WORKDIR /home/app
COPY pom.xml /home/app
COPY src /home/app/src
RUN mvn -f /home/app/pom.xml clean package

# RUN
FROM openjdk:17-jdk-alpine
COPY --from=build /home/app/target/*.jar app.jar
ENTRYPOINT ["java", "-Xmx2048M", "-jar", "app.jar"]

To build dockerfile:

docker build --tag=myspringapp:latest .

To run dockerfile:

docker run -p 8080:8080 myspringapp:latest

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