Rails 5.2 + Docker + Gitlab Continuous Deployment

.gitlab-ci.yml

image: ruby:2.6

services:
  - postgres:11-alpine

variables:
  POSTGRES_DB: myorg_test
  CONTAINER_IMAGE: registry.gitlab.com/myorg/myapp

stages:
  - test
  - build

cache:
  paths:
    - .bundle
    - vendor/ruby

test:
  stage: test

  script:
    - apt-get update -qy
    - apt-get install -y nodejs
    - bundle install --path .bundle
    - cp .env.ci .env
    - cp config/database.ci.yml config/database.yml
    - bundle exec rake db:create db:schema:load RAILS_ENV=test || true
    - bundle exec rake db:migrate RAILS_ENV=test
    - bundle exec rspec
    - bundle exec cucumber

build:
  stage: build

  image: docker:stable

  services:
    - docker:dind

  before_script:
    - docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN registry.gitlab.com

  script:
    - docker pull $CONTAINER_IMAGE:master || true
    - docker build --cache-from $CONTAINER_IMAGE:master --tag $CONTAINER_IMAGE:$CI_COMMIT_REF_NAME .
    - docker push $CONTAINER_IMAGE:$CI_COMMIT_REF_NAME

bin-prod-start

#!/bin/sh
bundle exec rake db:create
bundle exec rake db:migrate
bundle exec puma -C config/puma.rb

Dockerfile

FROM ruby:2.6-alpine AS base

RUN apk add --no-cache --update build-base \
                                git \
                                postgresql-dev \
                                nodejs \
                                tzdata

RUN mkdir /app
WORKDIR /app

# Add the Gemfile and bundle first, so changes to the app don't invalidate the
# cache
ADD Gemfile /app/Gemfile
ADD Gemfile.lock /app/Gemfile.lock
RUN bundle install --without development test --deployment

#
# Development stage
#
FROM base AS development
ENV RAILS_ENV development

RUN bundle install

ADD . /app

CMD bundle exec rails s

#
# Production stage
#
FROM base AS production

# Add the rest of the app
ADD . /app

ENV RAILS_ENV production
ENV NODE_ENV production

# Build assets - n.b. the DATABASE_URL doesn't need to be valid, it's just to
# stop Rails complaining and saying that it isn't set
RUN bundle exec rake assets:precompile DATABASE_URL=postgresql://localhost/

EXPOSE 9292

CMD bin/prod-start

What is in .env.ci please?