Guides Guidelines

This guide documents guidelines for writing Ruby on Rails Guides. This guide follows itself in a graceful loop, serving itself as an example.

After reading this guide, you will know:

  • About the conventions to be used in Rails documentation.
  • How to generate guides locally.


Guides are written in GitHub Flavored Markdown. There is comprehensive documentation for Markdown, as well as a cheatsheet.


Each guide should start with motivational text at the top (that’s the little introduction in the blue area). The prologue should tell the reader what the guide is about, and what they will learn. As an example, see the Routing Guide.


The title of every guide uses an h1 heading; guide sections use h2 headings; subsections use h3 headings; etc. Note that the generated HTML output will use heading tags starting with <h2>.

Guide Title


### Sub Section

When writing headings, capitalize all words except for prepositions, conjunctions, internal articles, and forms of the verb “to be”:

#### Assertions and Testing Jobs inside Components
#### Middleware Stack is an Array
#### When are Objects Saved?

Use the same inline formatting as regular text:

##### The `:content_type` Option

Linking to the API

Links to the API ( are processed by the guides generator in the following manner:

Links that include a release tag are left untouched. For example

is not modified.

Please use these in release notes, since they should point to the corresponding version no matter the target being generated.

If the link does not include a release tag and edge guides are being generated, the domain is replaced by For example,


If the link does not include a release tag and release guides are being generated, the Rails version is injected. For example, if we are generating the guides for v5.1.0 the link


Please don’t link to manually.

API Documentation Guidelines

The guides and the API should be coherent and consistent where appropriate. In particular, these sections of the API Documentation Guidelines also apply to the guides:

HTML Guides

Before generating the guides, make sure that you have the latest version of Bundler installed on your system. You can find the latest Bundler version here. As of this writing, it’s v1.17.1.

To install the latest version of Bundler, run gem install bundler.


To generate all the guides, just cd into the guides directory, run bundle install, and execute:

$ bundle exec rake guides:generate


$ bundle exec rake guides:generate:html

Resulting HTML files can be found in the ./output directory.

To process and nothing else use the ONLY environment variable:

$ touch
$ bundle exec rake guides:generate ONLY=my_guide

By default, guides that have not been modified are not processed, so ONLY is rarely needed in practice.

To force processing all the guides, pass ALL=1.

If you want to generate guides in a language other than English, you can keep them in a separate directory under source (e.g. source/es) and use the GUIDES_LANGUAGE environment variable:

$ bundle exec rake guides:generate GUIDES_LANGUAGE=es

If you want to see all the environment variables you can use to configure the generation script just run:

$ rake


Please validate the generated HTML with:

$ bundle exec rake guides:validate

Particularly, titles get an ID generated from their content and this often leads to duplicates.

Kindle Guides


To generate guides for the Kindle, use the following rake task:

$ bundle exec rake guides:generate:kindle