docker-compose: add _JAVA_OPTIONS

[pascalgrimaud]

Related to jhipster/generator-jhipster#3791 and #283

I confirm what @danielbrutti said, about _JAVA_OPTIONS. Big thanks to him.
I needed this to reduce the memory use of all containers

It probably depends on the Docker base image, because I was pretty sure JAVA_OPTS should work.

Here all my tests:

jhipster-registry.yml :

version: '2'
services:
    jhipster-registry:
        container_name: jhipster-registry
        image: jhipster/jhipster-registry:v2.5.0
        volumes:
            - ./central-server-config:/central-config
        # When run with the "dev" Spring profile, the JHipster Registry will
        # read the config from the local filesystem (central-server-config directory)
        # When run with the "prod" Spring profile, it will read the config from a git repository
        # See http://jhipster.github.io/microservices-architecture/#registry_app_configuration
        environment:
            - SPRING_PROFILES_ACTIVE=dev
            - SECURITY_USER_PASSWORD=admin
            - SPRING_CLOUD_CONFIG_SERVER_NATIVE_SEARCH_LOCATIONS=file:./central-config/localhost-config/
            # - GIT_URI=https://github.com/jhipster/jhipster-registry/
            # - GIT_SEARCH_PATHS=central-config
        ports:
            - 8761:8761

jhipster-registry-java-opts.yml :

version: '2'
services:
    jhipster-registry-java-opts:
        container_name: jhipster-registry-java-opts
        image: jhipster/jhipster-registry:v2.5.0
        volumes:
            - ./central-server-config:/central-config
        # When run with the "dev" Spring profile, the JHipster Registry will
        # read the config from the local filesystem (central-server-config directory)
        # When run with the "prod" Spring profile, it will read the config from a git repository
        # See http://jhipster.github.io/microservices-architecture/#registry_app_configuration
        environment:
            - JAVA_OPTS=-Xmx512m -Xms256m
            - SPRING_PROFILES_ACTIVE=dev
            - SECURITY_USER_PASSWORD=admin
            - SPRING_CLOUD_CONFIG_SERVER_NATIVE_SEARCH_LOCATIONS=file:./central-config/localhost-config/
            # - GIT_URI=https://github.com/jhipster/jhipster-registry/
            # - GIT_SEARCH_PATHS=central-config
        ports:
            - 8761

jhipster-registry-java-options.yml :

version: '2'
services:
    jhipster-registry-java-options:
        container_name: jhipster-registry-java-options
        image: jhipster/jhipster-registry:v2.5.0
        volumes:
            - ./central-server-config:/central-config
        # When run with the "dev" Spring profile, the JHipster Registry will
        # read the config from the local filesystem (central-server-config directory)
        # When run with the "prod" Spring profile, it will read the config from a git repository
        # See http://jhipster.github.io/microservices-architecture/#registry_app_configuration
        environment:
            - _JAVA_OPTIONS=-Xmx512m -Xms256m
            - SPRING_PROFILES_ACTIVE=dev
            - SECURITY_USER_PASSWORD=admin
            - SPRING_CLOUD_CONFIG_SERVER_NATIVE_SEARCH_LOCATIONS=file:./central-config/localhost-config/
            # - GIT_URI=https://github.com/jhipster/jhipster-registry/
            # - GIT_SEARCH_PATHS=central-config
        ports:
            - 8761

Here my docker stats $(docker ps --format={{.Names}}) :

CONTAINER                        CPU %               MEM USAGE / LIMIT       MEM %               NET I/O             BLOCK I/O             PIDS
jhipster-registry-java-options   0.69%               367.4 MiB / 7.419 GiB   4.84%               8.524 kB / 648 B    1.688 MB / 12.76 MB   55
jhipster-registry-java-opts      0.86%               847.4 MiB / 7.419 GiB   11.15%              10.36 kB / 648 B    0 B / 28.61 MB        55
jhipster-registry                0.83%               916.2 MiB / 7.419 GiB   12.06%              14.42 kB / 648 B    60.69 MB / 4.317 MB   55

[jdubois]

Really nice work!!
I'd like to understand why we need an underscore before JAVA_OPTS, I will look at this before merging.