Bundler 2 is not installing inside docker
set BUNDLER_VERSION environment variable inside Dockerfile:
ENV BUNDLER_VERSION=2.0.2or if you have docker.env:
BUNDLER_VERSION=2.0.2
I faced this problem also but as well as defining the BUNDLER_VERSION environment variable, I also needed to install that version into my container.
My Dockerfile therefore would look like:
FROM ruby:2.3.4-alpineWORKDIR "/var/www/app"ENV BUNDLER_VERSION=2.0.2COPY Gemfile GemfileCOPY Gemfile.lock Gemfile.lockRUN gem install bundler -v "$BUNDLER_VERSION" && bundle install