Single Docker Image Multiple Container For Multi Module Java Project-CodePudding

I have created a project like https://github.com/senolatac/demo-multi-module-docker and I have implemented some docker multi-stage https://docs.docker.com/language/java/run-tests/ examples.

Here is my Dockerfile:

FROM --platform=linux/x86_64 gradle:7.5.1-jdk17-alpine AS base
COPY --chown=gradle:gradle . /app
WORKDIR /app

FROM base as test
CMD ["./gradlew", "test"]

FROM base as build
RUN ./gradlew build -x test

# create-image -> DOCKER_BUILDKIT=0 docker build --tag sb-web-image --target web .
# run -> docker run -it --rm --name sb-web-container -p 8085:8080 sb-web-image
FROM --platform=linux/x86_64 openjdk:17-alpine as web
COPY --from=build /app/web/build/libs/*.jar /web.jar
CMD ["java", "-Dspring-boot.run.profiles=default", "-jar", "/web.jar"]

# create-image -> DOCKER_BUILDKIT=0 docker build --tag sb-worker-image --target worker .
# run -> docker run -it --rm --name sb-worker-container -p 8086:8080 sb-worker-image
FROM --platform=linux/x86_64 openjdk:17-alpine as worker
COPY --from=build /app/worker/build/libs/*.jar /worker.jar
CMD ["java", "-Dspring-boot.run.profiles=default", "-jar", "/worker.jar"]

# create-image -> DOCKER_BUILDKIT=0 docker build --tag sb-web-image --build-arg JAR_FILE=web/build/libs/\*.jar --target generic .
# run -> docker run -it --rm --name sb-web-container -p 8086:8080 sb-web-image
FROM --platform=linux/x86_64 openjdk:17-alpine as generic
ARG JAR_FILE
COPY --from=build /app/${JAR_FILE} /app.jar
CMD ["java", "-Dspring-boot.run.profiles=default", "-jar", "/app.jar"]

My project has two different modules. To run these modules on Docker, firstly I should create two different images then run them as two different docker container. But my purpose is so simple: Create a single image and run containers from that image. Do you have suggestion about it?

CodePudding user response：

You can straightforwardly override the CMD when you run the application, so you just need to COPY all of the jar files into the single image.

FROM --platform=linux/x86_64 gradle:7.5.1-jdk17-alpine AS build
COPY --chown=gradle:gradle . /app
WORKDIR /app
RUN ./gradlew build -x test

FROM --platform=linux/x86_64 openjdk:17-alpine
WORKDIR /app
COPY --from=build /app/web/build/libs/*.jar ./web.jar
COPY --from=build /app/worker/build/libs/*.jar ./worker.jar
ENV SPRINGBOOT_RUN_PROFILES=default
EXPOSE 8080
CMD ["java", "-jar", "./web.jar"]

docker build -t sb-image .
docker run -d --name sb-web -p 8085:8080 sb-image
docker run -d --name sb-worker -p 8086:8080 sb-image \
  java -jar ./worker.jar

So, note that there is only one final stage, but it COPY --from=build both jar files into it. I pick one of them to be the default CMD, and when I run the other, I provide an additional command after the docker run image-name. (Compose command: and Kubernetes args: can do the same thing.)

This looks like a Spring Boot application. I've set the profile property as an environment variable rather than a command-line option, which shortens the command line. If your applications share a code base, you can also get a smaller image by unpacking the fat jars, though this requires an additional build stage.