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Last pushed: 2 years ago
Short Description
Rails is an open-source web application framework written in Ruby.
Full Description


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 nodejs, mysql-client, postgresql-client, and sqlite3 for various uses of the rails framework.

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 . .

CMD ["rails", "server", "-b", ""]

Supported tags and respective Dockerfile links

Quick reference

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

Create a Dockerfile in your Rails app project

FROM rails:onbuild

Put this file in the root of your app, next to the Gemfile.

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 rails server.

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://localhost:8080 or http://host-ip:8080 in a browser.

Generate a Gemfile.lock

The onbuild tag expects a Gemfile.lock in your app directory. This docker run will help you generate one. Run it in the root of your app, next to the Gemfile:

$ 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.

Image Variants

The 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.

While the 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 docker/docker#5714, docker/docker#8240, docker/docker#11917).

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 onbuild variant 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-ONBUILD steps).


View license information for the software contained in this image.

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