Build a minimal Docker image for Rails
- Base your Docker image off
ruby:3-alpine, and add a few packages:build-baseto compile native extensions,nodejsfor a JS runtime,yarnfor JS dependency management (both required for Webpack), andsqlite-devfor SQLite (the default database used in a new Rails installation).
FROM ruby:3-alpine
RUN apk update
RUN apk add --no-cache \
build-base \
nodejs \
yarn \
sqlite-dev
WORKDIR /app
-
Build the image:
docker build . --tag minimal_rails_image -
Get in, loser!
docker run --rm --interactive --tty --volume $(pwd):/app minimal_rails_image sh -
Install the rails gem:
gem install rails -
Bootstrap a new Rails application:
rails new . -
Add tzinfo (Alpine doesn’t have it, apparently); remove the
platforms:arg from thegem 'tzinfo-data'line. I also had to remove the reference for it in the lockfile, before runningbundle installagain -
Generate webpacker config:
rails webpacker:install -
Grow old and die waiting for the horrific nightmare that is modern front-end
-
Modify the Dockerfile to be able to re-build the image and run Rails in dev mode:
COPY Gemfile Gemfile.lock /app/
RUN bundle install
EXPOSE 3000
CMD ["rails", "server", "--binding=0.0.0.0"]
-
Re-build the image:
docker build . --tag minimal_rails_image -
Run it (detached):
docker run --rm --detach --name rails_container --volume $(pwd):/app --publish 3000:3000 minimal_rails_image. You should now be able to hitlocalhost:3000in your browser and see the “Welcome to Rails” splash page. -
Rails console in running container:
docker exec --interactive --tty rails_container rails c -
Tail logs:
docker logs --follow rails_container -
Shell prompt:
docker exec --interactive --tty rails_container sh
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