GitHub Pages: publish your Grails plugin docs

Currently, the primary site for Grails plugin documentation is the plugin portal on the Grails web site. The trouble with the portal is that it doesn’t readily support multi-page documentation. On top of that, you can use gdoc to write a user guide for your plugin, but where will the generated manual go?

Thanks to Luke Daley, I discovered GitHub Pages as a potential solution for those plugins I have hosted on GitHub. This feature allows you to create simple websites on a per-project basis.

Getting started

Before you can start publishing websites to GitHub, you first have to create a ‘personal’ page. The process is straightforward: create a new GitHub repository, clone it locally, add an index page, and then push your additions to GitHub.

For example, let’s say your GitHub username is ‘franklin’. First, create a new GitHub repository with the name franklin.github.com. This repository will store your personal website. Once that’s ready, clone it and add an index page:

$ git clone git@github.com:franklin/franklin.github.com.git franklin.github.com
$ cd franklin.github.com
$ touch index.html
$ git add .
$ git push origin master

After the above steps, you will have a blank home page for http://franklin.github.com/. Note that it can take a while for your GitHub Pages site to activate. Also, you can access the URL http://<username>.github.com/ before you perform the above steps and you will see some instructions for setting up the various pages.

Now that you have a personal Pages site, you can create project sites with URLs of the form http://<username>.github.com/<projectname>/. The process for this is trickier, so I refer you to the instructions on the GitHub Pages. You can either do it via your local git, or you can got to the project page on GitHub, click on the “admin” button, and select the “Generate project page” link. I prefer the latter approach because it’s easier and involves less typing!

Once you complete the steps from either set of instructions, you will end up with an extra local tracking branch called ‘gh-pages’. This branch contains the website for your project and it’s where we will be storing the plugin documentation.

The plugin documentation

When the grails doc command first appeared, it allowed you to automatically generate API documentation for your projects. With Grails 1.2, its scope was expanded and it can now generate a manual that looks and feels just like the Grails user guide. You don’t have to do anything to get the API documentation, but the manual requires a bit of work.

The basic idea is that you create a src/docs/guide directory and populate it with gdoc files. By prefixing the names of the gdoc files with appropriate numbers, you get a hierarchy of numbered sections. To get some idea of what you need to do, check out the source files that Luke Daley created for the Grails JMS plugin user guide.

Publishing the docs

Generating the documentation leaves you with a docs directory full of HTML files. What do you do with it? The next step is to get it onto your project-specific GitHub Pages site. Doing this manually is a bit of a bind, but I’ve created a Grails script and some template files that make it almost trivially easy (once you have the ‘gh-pages’ branch locally!).

First, copy this script to your $HOME/.grails/scripts directory. Next, switch to your ‘gh-pages’ branch and copy this HTML template to the root directory of the project. Next, create an index page for your site: index.html, index.textile, and index.markdown are all acceptable. Choose whichever format you prefer, but it should start with this section:

---
layout: main
title: My Grails Plugin
---

The three dashes are important! I’ll explain those and the layout/title later. Then,

$ git add main.html.tmpl
$ git add index.textile
$ git commit -m "Adding template layout and index page for GitHub Pages site."

In the above set of commands, replace ‘index.textile’ with the name of the index file you created.

You’re now ready to publish your plugin docs for the first time! Simply switch to the main branch and execute the new Grails command:

$ git checkout master
$ grails publish-github

Once the command successfully completes, you will find yourself back on the ‘gh-pages’ branch with all the documentation staged for a commit. You can then make any changes you want, commit everything, and then push the branch to GitHub. You can even do this in one step with the grails publish-github --push command, or if you want to automatically commit the documentation but not push, use grails publish-github --commit.

A few details

The publish-github command does a few things. First, it generates the plugin’s documentation via Grails’ doccommand. It then copies the generated documentation to the ‘gh-pages’ branch (using an rather ugly technique). Once it’s on the ‘gh-pages’ branch, it generates a new ‘main’ layout based on the main.html.tmpl file. It basically reads the information from the XML plugin descriptor, plugin.xml, and populates the template with things like the plugin version and author. The template is then generated to _layouts/main.html, which you can reference from your individual pages.

It’s up to you to write the site’s pages, but at least you have the option of three different syntax types. I prefer Textile for the moment, because it’s very similar to the gdoc format. The key part of each page is the header block, which you’ve seen already:

---
layout: main
title: My Grails Plugin
---

The ‘layout’ value is used to determine which file under _layouts to inject the page into. Ideally, the index page should use the _layouts/main.html template that the publish-github command generates, hence the value ‘main’. The ‘title’ option is specific to the generated template, which inserts the corresponding value into the title of the page. This is because it’s tough to get a suitable plugin name with correct capitalisation from the plugin descriptor.
Update Somebody has pointed out that the publish-github command doesn’t work if plugin.xml is committed to your main branch (typically master). You could try modifying the script to handle this, but the XML plugin descriptor doesn’t need to be in GitHub at all – it’s generated after all – so I would simply git rm it.

That’s pretty much it. You also have the full power of Jekyll (as described on the GitHub site), so you can build more elaborate sites as you see fit. If you want to see the results of all this jiggery-pokery, then take a look at the GWT plugin pages.

Until next time.