Get Jekyll Configuration Inside Plugin - ruby

Question

I'd like to make changes to the Jekyll Only First Paragraph plugin to make the generation of a 'read more ' link a configurable option.
To do this I'd need to be able to access the Jekyll site config inside the plugin's AssetFilter. With the configuration available I can make the change. I don't know how to make the site configuration available to the plugin.
The code below demonstrates where I'd like site.config available:
require 'nokogiri'
module Jekyll
module AssetFilter
def only_first_p(post)
# site.config needs to be available here to modify the output based on the configuration
output = "<p>"
output << Nokogiri::HTML(post["content"]).at_css("p").inner_html
output << %{</p><a class="readmore" href="#{post["url"]}">Read more</a>}
output
end
end
end
Liquid::Template.register_filter(Jekyll::AssetFilter)
Can this be achieved?

Answer 1

Overview
You can access Jekyll config options in plugins with:
Jekyll.configuration({})['KEY_NAME']
If the config key contains nested levels, the format is:
Jekyll.configuration({})['KEY_LEVEL_1']['KEY_LEVEL_2']
Example
If a _config.yml contains:
testvar: new value
custom_root:
second_level: sub level data
A basic example that simply outputs those values would look like:
require 'nokogiri'
module Jekyll
module AssetFilter
def only_first_p(post)
#c_value = Jekyll.configuration({})['testvar']
#c_value_nested = Jekyll.configuration({})['custom_root']['second_level']
output = "<p>"
### Confirm you got the config values
output << "<br />"
output << "c_value: " + #c_value + "<br />"
output << "c_value_nested: " + #c_value_nested + "<br />"
output << "<br />"
###
output << Nokogiri::HTML(post["content"]).at_css("p").inner_html
output << %{</p><a class="readmore" href="#{post["url"]}">Read more</a>}
output
end
end
end
Liquid::Template.register_filter(Jekyll::AssetFilter)
Of course, you would want to put checks in that verify that the config key/values are defined before trying to use them. That's left as an exercise for the reader.
Another Possible Option
The "Liquid filters" section of the Jekyll Plugins Wiki Page contains the following:
In Jekyll you can access the site object through registers. As an example, you can access the global configuration (_config.yml) like this: #context.registers[:site].config['cdn'].
I haven't spent the time to get that to work, but it might be worth checking out as well.

Answer 2

Jekyll.configuration({})['KEY_NAME'] will break the --config command line option because it will always load the configurations from the _config.yml file. Another bad side effect is that it will read the _config.yml file again.
context.registers[:site].config['KEY_NAME'] is the correct answer because it will get the key from the configurations already loaded by Jekyll.

Answer 3

If you are working with Generators (which are also plugins), it is possible to get the configuration like this:
class MyPlugin < Jekyll::Generator
def generate(site)
puts site.config["max_posts"] # max_posts as defined in _config.yml
You'll get the site as an argument, and the .config is accessible as an hash.