[FIXED] Best practice for dockerizing a springboot app in a CICD pipeline

Issue

Context: I'm able to dockerize and run my Springboot app locally just fine with the below, following the most common recommendations of using a generated jar file to run the app via Docker.

Question: Since it's bad practice to push the jar file to the repo as it's going to potentially contain secrets from the local application.yml files, and the docker file depends on the jar file, how can I have my app be dockerized not just locally but on the cloud in anywhich cicd pipeline? Would my next step be modifying the dockerfile to copy over the project directory, and handle generating the jar file itself? Or should I not be using a jar at all and copying over the directory and using a CMD [Some Spring Run command)]

DockerFile:

FROM maven:3.8.5-openjdk-17
ADD target/xyz.jar xyz.jar

ENV RESTFUL_PORT 8080
ENV PORT_POSTGRES 5432
EXPOSE $RESTFUL_PORT
EXPOSE $PORT_POSTGRES

ENTRYPOINT ["java", "-jar","/xyz.jar"]

The pom.xml plugin which generates the jar file:

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.10.1</version>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                </configuration>
            </plugin>

Docker Steps

1. Build the Jar: mvn clean install
2. Build the Image: docker build -t xyz -f Dockerfile
3. Run the Image: docker run -d -p 8080:8080 -e "SPRING_PROFILES_ACTIVE=dev" xyz

Solution

The Dockerfile can be like this:

# Build Stage
FROM maven:3.8-openjdk-17-slim AS build
COPY src /home/app/src
COPY pom.xml /home/app
RUN mvn -f /home/app/pom.xml clean package

# Execution Stage
FROM openjdk:17-oracle
COPY --from=build /home/app/target/demo-0.1-SNAPSHOT.jar /usr/local/lib/demo.jar
EXPOSE 8080
ENTRYPOINT ["java","-jar","/usr/local/lib/demo.jar"]

To build docker image

$ docker build -t demo-app:1.0 .   

Run docker image

$ docker run -p 8080:8080 demo-app:1.0

Simple build part of pom.xml will work

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

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