Ruby on RailsEstimated reading time: 6 minutes
Rails is an open-source web application framework written in Ruby.
GitHub repo: https://github.com/docker-library/rails
This image is officially deprecated in favor of the standard
ruby image, and will receive no further updates after 2016-12-31 (Dec 31, 2016). Please adjust your usage accordingly.
For most usages of this image, it was already not bringing in
rails from this image, but actually from your project’s
Gemfile, so the only “value” being added here was the pre-installing of
sqlite3 for various uses of the
For example, a
Dockerfile similar to the following would be a good starting point for a Rails project using PostgreSQL:
FROM ruby:2.3 RUN apt-get update \ && apt-get install -y --no-install-recommends \ postgresql-client \ && rm -rf /var/lib/apt/lists/* WORKDIR /usr/src/app COPY Gemfile* ./ RUN bundle install COPY . . EXPOSE 3000 CMD ["rails", "server", "-b", "0.0.0.0"]
Supported tags and respective
For detailed information about the published artifacts of each of the above supported tags (image metadata, transfer size, etc), please see the
repos/rails directory in the
docker-library/repo-info GitHub repo.
For more information about this image and its history, please see the relevant manifest file (
library/rails). This image is updated via pull requests to the
docker-library/official-images GitHub repo.
What is Ruby on Rails?
Ruby on Rails or, simply, Rails is an open source web application framework which runs on the Ruby programming language. It is a full-stack framework. This means that “out of the box”, Rails can create pages and applications that gather information from a web server, talk to or query a database, and render templates. As a result, Rails features a routing system that is independent of the web server.
How to use this image
Dockerfile in your Rails app project
Put this file in the root of your app, next to the
This image includes multiple
ONBUILD triggers which should cover most applications. The build will
COPY . /usr/src/app,
RUN bundle install,
EXPOSE 3000, and set the default command to
You can then build and run the Docker image:
$ docker build -t my-rails-app . $ docker run --name some-rails-app -d my-rails-app
You can test it by visiting
http://container-ip:3000 in a browser or, if you need access outside the host, on port 8080:
$ docker run --name some-rails-app -p 8080:3000 -d my-rails-app
You can then go to
http://host-ip:8080 in a browser.
onbuild tag expects a
Gemfile.lock in your app directory. This
run will help you generate one. Run it in the root of your app, next to the
$ docker run --rm -v "$PWD":/usr/src/app -w /usr/src/app ruby:2.1 bundle install
Bootstrap a new Rails application
If you want to generate the scaffolding for a new Rails project, you can do the following:
$ docker run -it --rm --user "$(id -u):$(id -g)" -v "$PWD":/usr/src/app -w /usr/src/app rails rails new --skip-bundle webapp
This will create a sub-directory named
webapp inside your current directory.
rails images come in many flavors, each designed for a specific use case.
This is the defacto image. If you are unsure about what your needs are, you probably want to use this one. It is designed to be used both as a throw away container (mount your source code and start the container to start your app), as well as the base to build other images off of.
This image makes building derivative images easier. For most use cases, creating a
Dockerfile in the base of your project directory with the line
FROM rails:onbuild will be enough to create a stand-alone image for your project.
onbuild variant is really useful for “getting off the ground running” (zero to Dockerized in a short period of time), it’s not recommended for long-term usage within a project due to the lack of control over when the
ONBUILD triggers fire (see also
Once you’ve got a handle on how your project functions within Docker, you’ll probably want to adjust your
Dockerfile to inherit from a non-
onbuild variant and copy the commands from the
Dockerfile (moving the
ONBUILD lines to the end and removing the
ONBUILD keywords) into your own file so that you have tighter control over them and more transparency for yourself and others looking at your
Dockerfile as to what it does. This also makes it easier to add additional requirements as time goes on (such as installing more packages before performing the previously-
View license information for the software contained in this image.
Supported Docker versions
This image is officially supported on Docker version 17.04.0-ce.
Support for older versions (down to 1.6) is provided on a best-effort basis.
Please see the Docker installation documentation for details on how to upgrade your Docker daemon.
If you have any problems with or questions about this image, please contact us through a GitHub issue. If the issue is related to a CVE, please check for a
cve-tracker issue on the
official-images repository first.
You can also reach many of the official image maintainers via the
#docker-library IRC channel on Freenode.
You are invited to contribute new features, fixes, or updates, large or small; we are always thrilled to receive pull requests, and do our best to process them as fast as we can.
Before you start to code, we recommend discussing your plans through a GitHub issue, especially for more ambitious contributions. This gives other contributors a chance to point you in the right direction, give you feedback on your design, and help you find out if someone else is working on the same thing.
Documentation for this image is stored in the
rails/ directory of the
docker-library/docs GitHub repo. Be sure to familiarize yourself with the repository’s
README.md file before attempting a pull request.