Douglas allows you to extend and augment its base functionality with plugins. Plugins allow you to:

  • create additional variables
  • provide additional entry parsers, renderers, post-formatters, and pre-formatters
  • create new output data types
  • pull information from other non-blog sources
  • create images
  • and a variety of other things

Plugins hook into Douglas using callbacks which allow plugins to handle, transform, override and otherwise affect Douglas’s behavior.

Setting Douglas up to use plugins

There are two properties in your file that affect the behavior for loading plugins: plugin_dirs and load_plugins. There’s more documentation on these in Configuration variables.

Finding plugins

Douglas comes with a core set of plugins. Documentation for these plugins is in Part 2: Core plugin documentation.

Additionally, you can write your own plugins.

Installing plugins

When you’re installing a plugin, refer to its documentation. The documentation could be in a README file, but more commonly it’s in the plugin code itself at the top of the file. This documentation should tell you how to install the plugin, what template variables the plugin exposes, how to invoke the plugin, how to get in touch with the author should you find bugs or need help, and any additional things you should know about.

Most plugins should have a pretty easy installation method. You should be able to copy the plugin into the directory defined in your file in the plugin_dirs property. Then there might be some additional properties you’ll have to set in your file to define the plugin’s behavior. That should be about it. On some occasions, you may have to change the code in the plugin itself to meet your specific needs.

Writing your own plugins

You may find that you desire functionality and there is no plugin that anyone knows about that performs that functionality. It’s probably best at this point for you to ask someone to write the plugin you need or write it yourself.

Douglas plugins are fairly easy to write and can cover a lot of really different functionality. The best way to learn how to write Douglas plugins is to read through the plugins in the plugin registry. Many of them are well written and may provide insight as to how to solve your specific problem.

If you plan on writing your own plugin, check out Writing Plugins.