获取 RVM 路径后，在 Docker 容器内找不到 Gems

Question

scenario1

So the problem I am facing like after building the docker images. If I am going inside the docker container and doing GEM_PATH=$GEM_HOME gem list it is not showing all the gems installed at the time of building the image. it is showing only a few gems.

scenario2

If I am not sourcing the RVM path inside the Dockerfile. Then If I am going inside the docker container and doing GEM_PATH=$GEM_HOME gem list then it is showing all the gems.

Can anyone please explain to me why this is happening and how I should install and source RVM? So I can see all the gems inside the container. Basically, I want the scenario1 should work. Thanks

Below is my Dockerfile

FROM ruby:2.6.5
RUN apt-get update -qq && apt-get install -y sudo && apt-get install -y build-essential && apt-get install -y apt-utils && apt-get install -y git
RUN gpg --keyserver hkp://pool.sks-keyservers.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB && \curl -sSL https://get.rvm.io | sudo bash -s stable --ruby && echo 'source /usr/local/rvm/scripts/rvm' >> /etc/bash.bashrc
RUN /bin/bash -l -c 'gem install bundler -v 1.17.3'
RUN /bin/bash -l -c 'gem install rails --version=5.2.4.1'
WORKDIR /app
RUN bundle config build.nokogiri --use-system-libraries
RUN bundle config set path 'vendor/bundle'
COPY Gemfile Gemfile.lock ./
ARG SSH_KEY
# Make ssh dir
RUN mkdir /root/.ssh/
# Copy ssh
RUN echo "$SSH_KEY" > /root/.ssh/id_rsa && \
   chmod 0600 /root/.ssh/id_rsa
RUN touch /root/.ssh/known_hosts
# Add bitbuckets key
RUN ssh-keyscan bitbucket.org >> /root/.ssh/known_hosts
RUN bundle install
COPY . ./
EXPOSE 80:80
CMD rails s -p 80 -b '0.0.0.0' -e qa

Answer 1

TL;DR : don't use rvm\\rbenv within a container

the whole thing when using containers, is to bundle\\package all the dependencies inside a container. for instance, if you need ruby 2.9 then use a docker image which has ruby 2.9 installed rather than using rvm [rbenv]( https://github.com/rbenv/rbenv ).

since you are using bundler , i will advise you to add rails gem to it, and let bundler manage the dependencies.

i assume that you care about the directory where rubygems are being installed for caching propose, and i see that you instruct bundler exactly what is the rubygem home directory

RUN bundle config set path 'vendor/bundle'