CODEWITHSUNDEEP
javadockerspring-bootkotlindockerfile
Idir Ouhab Meskine
Idir Ouhab Meskine

Reputation: 587

Dockerizing a Springboot app

Context: It's an application written in Kotlin and using Spring-boot with Maven.

Basically, I'd like to know if it makes sense what I'm doing.

Running mvn install then the target folder will be created with the corresponding jar file. Therefore the Dockerfile will be just copying the jar file into the working directory of the container and run java -jar WHATEVER.jar.

Example of the simple Dockerfile

FROM openjdk:8-jre-alpine

COPY target/app-DEV-SNAPSHOT.jar .
EXPOSE 8089
CMD ["java", "-jar", "./app-DEV-SNAPSHOT.jar"]

But I'd say, makes much more sense to me to use the multi-stage building and in the first stage generate the jar file and in the second stage, execute it. I tried this second approach but I'm facing an issue with main class doesn't exist

Multi-stage Dockerfile:

FROM maven:3.5.2-jdk-8-alpine as BUILD

ENV APP_HOME=/usr/src/service
COPY ./src /usr/src/service
COPY pom.xml /usr/src/service
WORKDIR /usr/src/service
RUN mvn install
FROM openjdk:8-jre-alpine
COPY --from=BUILD /usr/src/service/target/app-DEV-SNAPSHOT.jar ./
EXPOSE 8080
CMD ["java", "-jar", "./app-DEV-SNAPSHOT.jar"]

Which one is the correct one?

Upvotes: 0

Views: 312

Answers (1)

Tarun Lalwani
Tarun Lalwani

Reputation: 146630

You should use the multistage dockerfile. Reason being you want to have least dependency on the host system. When you run mvn on host you add dependency of mvn and in turn java.

My recommendation would be to use multistage docker to build in one stage and copy to another stage

Upvotes: 1

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