Version: | 5 |
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Author: | Roberto Alsina <ralsina@netmanagers.com.ar> |
Note
This is a draft
I am not sure of the best way to do some things, including how to document this. Suggestions are welcome.
Nikola is extensible. Almost all its functionality is based on plugins, and you can add your own or replace the provided ones.
Plugins consist of a metadata file (with .plugin extension) and a python module (a .py file) or package (a folder containing a __init__.py file.
To use a plugin in your site, you just have to put it in a plugins folder in your site.
Plugins come in various flavours, aimed at extending different aspects of Nikola.
When you run nikola --help you will see something like this:
$ nikola --help Usage: nikola command [options] Available commands: nikola bootswatch_theme: Given a swatch name and a parent theme, creates a custom theme. nikola build: Build the site. nikola import_wordpress: Import a wordpress site from a XML dump. nikola init: Create a new site. nikola install_theme: Install a theme into the current site. nikola new_post: Create a new post. nikola serve: Start test server. For detailed help for a command, use nikola command --help
That will give you a list of all available commands in your version of Nikola. Each and every one of those is a plugin. Let's look at a typical example:
First, the command_serve.plugin file:
[Core] Name = serve Module = command_serve [Documentation] Author = Roberto Alsina Version = 0.1 Website = http://nikola.ralsina.com.ar Description = Start test server.
For your own plugin, just change the values in a sensible way. The Module will be used to find the matching python module, in this case command_serve.py, from which this is the interesting bit:
from nikola.plugin_categories import Command # You have to inherit Command for this to be a # command plugin: class CommandBuild(Command): """Start test server.""" # This has to match the Name option in the .plugin file name = "serve" # This is the function that does stuff def run(self, *args): """Start test server.""" # use OptionParser if you want your command to have options parser = OptionParser(usage="nikola %s [options]" % self.name) parser.add_option("-p", "--port", dest="port", help="Port numer (default: 8000)", default=8000, type="int") parser.add_option("-a", "--address", dest="address", help="Address to bind (default: 127.0.0.1)", default='127.0.0.1') (options, args) = parser.parse_args(list(args)) # You can use self.site.config to access your # configuration options. self.site is an instance # of the Nikola class and contains all your site's # data. out_dir = self.site.config['OUTPUT_FOLDER'] # Then do something interesting. In this case, # it starts a webserver if not os.path.isdir(out_dir): print "Error: Missing '%s' folder?" % out_dir else: os.chdir(out_dir) httpd = HTTPServer((options.address, options.port), OurHTTPRequestHandler) sa = httpd.socket.getsockname() print "Serving HTTP on", sa[0], "port", sa[1], "..." httpd.serve_forever()
As mentioned above, a plugin can have options, which the user can see by doing nikola command --help and can later use as nikola command --option:
$ nikola serve --help Usage: nikola serve [options] Options: -h, --help show this help message and exit -p PORT, --port=PORT Port numer (default: 8000) -a ADDRESS, --address=ADDRESS Address to bind (default: 127.0.0.1) $ nikola serve -p 9000 Serving HTTP on 127.0.0.1 port 9000 ...
So, what can you do with commands? Well, anything you want, really. I have implemented a sort of planet using it. So, be creative, and if you do something interesting, let me know ;-)
Nikola supports Mako and Jinja2. If you prefer some other templating system, then you will have to write a TemplateSystem plugin. Here's how they work. First, you have to create a .plugin file. Here's the one for the Mako plugin:
[Core] Name = mako Module = template_mako [Documentation] Author = Roberto Alsina Version = 0.1 Website = http://nikola.ralsina.com.ar Description = Support for Mako templates.
You will have to replace "mako" with your template system's name, and other data in the obvious ways.
The "Module" option is the name of the module, which has to look something like this, a stub for a hypothetical system called "Templater":
from nikola.plugin_categories import TemplateSystem # You have to inherit TemplateSystem class TemplaterTemplates(TemplateSystem): """Wrapper for Templater templates.""" # name has to match Name in the .plugin file name = "templater" # You *must* implement this, even if to return [] # It should return a list of all the files that, # when changed, may affect the template's output. # usually this involves template inheritance and # inclusion. def get_deps(self, filename): return [] # A list of directories where the templates will be # located. Most template systems have some sort of # template loading tool that can use this. def set_directories(self, directories): """Createa template lookup.""" pass # The method that does the actual rendering. # template_name is the name of the template file, # output_name is the file for the output, context # is a dictionary containing the data the template # uses for rendering. def render_template(self, template_name, output_name, context, global_context): """Render the template into output_name using context.""" pass
If you want to do something that depends on the data in your site, you probably want to do a Task plugin, which will make it be part of the nikola build command. There are the currently available tasks, all provided by plugins:
$ nikola list build_bundles copy_assets copy_files deploy redirect render_archive render_galleries render_indexes render_listings render_pages render_posts render_rss render_site render_sources render_tags sitemap
These have access to the site object which contains your timeline and your configuration.
The critical bit of Task plugins is their gen_tasks method, which yields doit tasks
The details of how to handle dependencies, etc. are a bit too much for this document, so I'll just leave you with an example, the copy_assets task. First the task_copy_assets.plugin file, which you should copy and edit in the logical ways:
[Core] Name = copy_assets Module = task_copy_assets [Documentation] Author = Roberto Alsina Version = 0.1 Website = http://nikola.ralsina.com.ar Description = Copy theme assets into output.
And the task_copy_assets.py file, in its entirety:
import os from nikola.plugin_categories import Task from nikola import utils # Have to inherit Task to be a task plugin class CopyAssets(Task): """Copy theme assets into output.""" name = "copy_assets" # This yields the tasks def gen_tasks(self): """Create tasks to copy the assets of the whole theme chain. If a file is present on two themes, use the version from the "youngest" theme. """ # I put all the configurations and data the plugin uses # in a dictionary because utils.config_changed will # make it so that if these change, this task will be # marked out of date, and run again. kw = { "themes": self.site.THEMES, "output_folder": self.site.config['OUTPUT_FOLDER'], "filters": self.site.config['FILTERS'], } tasks = {} for theme_name in kw['themes']: src = os.path.join(utils.get_theme_path(theme_name), 'assets') dst = os.path.join(kw['output_folder'], 'assets') for task in utils.copy_tree(src, dst): if task['name'] in tasks: continue tasks[task['name']] = task task['uptodate'] = task.get('uptodate', []) + \ [utils.config_changed(kw)] task['basename'] = self.name # If your task generates files, please do this. yield utils.apply_filters(task, kw['filters'])