[FIXED] How to dockerize maven project? and how many ways to accomplish it?

Issue

I am new to Docker, and don't know how to run a java project with maven even though I have read many documents and tried many methods.

1. Should I build the image using Dockerfile?
2. What is the commands like when it is to run the maven project in the host with Dockerfile?

Solution

Working example.

This is not a spring boot tutorial. It's the updated answer to a question on how to run a Maven build within a Docker container.

Question originally posted 4 years ago.

1. Generate an application

Use the spring initializer to generate a demo app

https://start.spring.io/

Extract the zip archive locally

2. Create a Dockerfile

#
# Build stage
#
FROM maven:3.6.0-jdk-11-slim AS build
COPY src /home/app/src
COPY pom.xml /home/app
RUN mvn -f /home/app/pom.xml clean package

#
# Package stage
#
FROM openjdk:11-jre-slim
COPY --from=build /home/app/target/demo-0.0.1-SNAPSHOT.jar /usr/local/lib/demo.jar
EXPOSE 8080
ENTRYPOINT ["java","-jar","/usr/local/lib/demo.jar"]

Note

• This example uses a multi-stage build. The first stage is used to build the code. The second stage only contains the built jar and a JRE to run it (note how jar is copied between stages).

3. Build the image

docker build -t demo .

4. Run the image

$ docker run --rm -it demo:latest

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.3.RELEASE)

2019-02-22 17:18:57.835  INFO 1 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication v0.0.1-SNAPSHOT on f4e67677c9a9 with PID 1 (/usr/local/bin/demo.jar started by root in /)
2019-02-22 17:18:57.837  INFO 1 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to default profiles: default
2019-02-22 17:18:58.294  INFO 1 --- [           main] com.example.demo.DemoApplication         : Started DemoApplication in 0.711 seconds (JVM running for 1.035)

Misc

Read the Docker hub documentation on how the Maven build can be optimized to use a local repository to cache jars.

• https://hub.docker.com/_/maven

  ---

Update (2019-02-07)

This question is now 4 years old and in that time it's fair to say building application using Docker has undergone significant change.

Option 1: Multi-stage build

This new style enables you to create more light-weight images that don't encapsulate your build tools and source code.

The example here again uses the official maven base image to run first stage of the build using a desired version of Maven. The second part of the file defines how the built jar is assembled into the final output image.

FROM maven:3.5-jdk-8 AS build  
COPY src /usr/src/app/src  
COPY pom.xml /usr/src/app  
RUN mvn -f /usr/src/app/pom.xml clean package

FROM gcr.io/distroless/java  
COPY --from=build /usr/src/app/target/helloworld-1.0.0-SNAPSHOT.jar /usr/app/helloworld-1.0.0-SNAPSHOT.jar  
EXPOSE 8080  
ENTRYPOINT ["java","-jar","/usr/app/helloworld-1.0.0-SNAPSHOT.jar"]  

Note:

• I'm using Google's distroless base image, which strives to provide just enough run-time for a java app.

Option 2: Jib

I haven't used this approach but seems worthy of investigation as it enables you to build images without having to create nasty things like Dockerfiles :-)

https://github.com/GoogleContainerTools/jib

The project has a Maven plugin which integrates the packaging of your code directly into your Maven workflow.

---

Original answer (Included for completeness, but written ages ago)

Try using the new official images, there's one for Maven

https://registry.hub.docker.com/_/maven/

The image can be used to run Maven at build time to create a compiled application or, as in the following examples, to run a Maven build within a container.

Example 1 - Maven running within a container

The following command runs your Maven build inside a container:

docker run -it --rm \
       -v "$(pwd)":/opt/maven \
       -w /opt/maven \
       maven:3.2-jdk-7 \
       mvn clean install

Notes:

• The neat thing about this approach is that all software is installed and running within the container. Only need docker on the host machine.
• See Dockerfile for this version

Example 2 - Use Nexus to cache files

Run the Nexus container

docker run -d -p 8081:8081 --name nexus sonatype/nexus

Create a "settings.xml" file:

<settings>
  <mirrors>
    <mirror>
      <id>nexus</id>
      <mirrorOf>*</mirrorOf>
      <url>http://nexus:8081/content/groups/public/</url>
    </mirror>
  </mirrors>
</settings>

Now run Maven linking to the nexus container, so that dependencies will be cached

docker run -it --rm \
       -v "$(pwd)":/opt/maven \
       -w /opt/maven \
       --link nexus:nexus \
       maven:3.2-jdk-7 \
       mvn -s settings.xml clean install

Notes:

• An advantage of running Nexus in the background is that other 3rd party repositories can be managed via the admin URL transparently to the Maven builds running in local containers.

Answered By - Mark O'Connor