Docker, Docker compose - how to run RSpec tests

Question

Can anybody point it out, - what is the best approach to run RSpec tests on a Rails API app inside a Docker container (during the container build/run) ?

The aim is to be able to separate the development environment from other ones and to run tests only in development mode, start Puma server only in staging, production environments.

What is the right place to put bundle exec rspec command, - in a separate entrypoint.sh script, Directly in Dockerfile, docker-compose.yml file, or other solutions?

All the Googles results as well as Docker for Rails Developers book by PragProg have no examples and the only way to run the tests theys provide is to run them against an already running container.

Actually, my Dockerfile looks like that:

FROM ruby:2.6.1

RUN apt-get update -yqq
RUN apt-get install -yqq --no-install-recommends build-essential zip unzip libpq-dev libaio1 libaio-dev nodejs

ENV APP_HOME=/usr/src/app
ENV BUNDLE_PATH /gems

COPY . $APP_HOME

RUN echo "gem: --no-rdoc --no-ri" >> ~/.gemrc

WORKDIR $APP_HOME
RUN gem update --system
RUN gem install bundler
RUN bundle install

RUN ["chmod", "+x", "entrypoint.sh"]
CMD ["./entrypoint.sh"]

The entrypoint.sh looks like that:

#!/bin/bash

set -e

if [ -f tmp/pids/server.pid ]; then
  rm tmp/pids/server.pid
fi

./wait-for-it.sh ${DATABASE_HOST}:${DATABASE_PORT}

if [ -z "$RAILS_ENV" ]; then
  echo "RAILS_ENV variable is not set, will use development by default"
  bundle exec rails db:reset
  bundle exec rails db:migrate
  bundle exec rspec
else
  bundle exec rails s -e $RAILS_ENV -p 3000 -b 0.0.0.0
fi

And finally, docker-compose.yml:

version: '3.3'

services:
  api:
    build: ../..
    ports:
      - '3000:3000'
    volumes:
      - .:/usr/src/app
      - gem_cache:/gems
    env_file:
      - ./env/database.env
      - ./env/web.env
    depends_on:
      - database
    # Keeps the stdin open, so we can attach to our app container's process and
    # do stuff such as `byebug` or `binding.pry`:
    stdin_open: true
    # Allows us to send signals (CTRL+C, CTRL+P + CTRL+Q) into the container
    tty: true
  database:
    image: postgres:9.6
    env_file:
      - ./env/database.env
    volumes:
      - db-data:/var/lib/postgresql/data
    ports:
      - 5432:5432
volumes:
  db-data:
  gem_cache:

Thank you.

Answer 1

try

docker-compose run -e "RAILS_ENV=test" api bundle exec rspec spec/link/to/file.rb