JDK 8 installed even though JDK 11 is mentioned in Dockerfile

General
1

I need to create a docker container for my app with JDK 11 installed. My docker file looks like below:

ARG env_=local
FROM openjdk:11-jdk
LABEL maintainer=myapp artifact=pro-web-admin
ENV ENV_NAME=$env_
EXPOSE 9090
ENV USER root
ADD build/libs/pro-web-admin-0.0.1-SNAPSHOT.jar pro-web-admin.jar
ENTRYPOINT ["java","-jar","/pro-web-admin.jar"]

And my docker-compose.yml looks like below:

version: '3.8'
services:
  postgresqldb:
    image: postgres
    ports:
      - "5432:5432"
    network_mode: host
    environment:
      - POSTGRES_PASSWORD=root
      - POSTGRES_USER=root
      - POSTGRES_DB=testdb
  app:
    container_name: pro-web-admin
    image: pro-web-admin
    build: ./
    ports:
      - "9090:9090"
    network_mode: host
    depends_on:
      - postgresqldb
    environment:
      - USER=root

But I’m still seeing JDK version 8 inside the docker container:

1298×183 45.4 KB

Am I missing something here? I don’t see any discrepancy in the configuration. Can anyone please point out what’s wrong here? Really appreciate your valuable suggestions. Thanks in advance!

2

Quick guess, which is better than nothing.

Thinking update-alternatives.

3

Thank you for the response. How to configure this in docker-compose.yml ?
Does this mean I can’t run JDK 11 app using docker compose?

4

Hmm, the problem is not originated in the base image:

me@docker~$ docker run -ti openjdk:11-jdk java -version
Unable to find image 'openjdk:11-jdk' locally
11-jdk: Pulling from library/openjdk
e4c3d3e4f7b0: Pull complete
101c41d0463b: Pull complete
8275efcd805f: Pull complete
751620502a7a: Pull complete
a59da3a7d0e7: Pull complete
9c0f1dffe039: Pull complete
474314d81831: Pull complete
Digest: sha256:d8af704f3022f5c44b4340c58e62313c706301915ec00291eec0749fc5378c3b
Status: Downloaded newer image for openjdk:11-jdk
openjdk version "11.0.9" 2020-10-20
OpenJDK Runtime Environment 18.9 (build 11.0.9+11)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.9+11, mixed mode)

Your Dockerfile shows no indication of alteration of the java configuration either. No entrypoint scripts, thus no hidden actions.
What you observe is impossible with a fresh build image based on your Dockerfile.

Sure it is a fresh builld and not just an old image that happens to have the same name and tag?

update:

me@docker~$ docker run -ti openjdk:11-jdk cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 10 (buster)"
NAME="Debian GNU/Linux"
VERSION_ID="10"
VERSION="10 (buster)"
VERSION_CODENAME=buster
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

The container you checked is based on Alpine and deffinitly not an image based on a current version of the base image, which is based on Debian.

Looks like a pebkac :grin:

5

You’re right.
I was referring to an old image for docker compose and that was the reason for JDK 8.
Thank you for point it out.