How to make Redcarpet optionally filter HTML tags?

I would like to whitelist some HTML tags, for example <kbd></kbd> so that I can show pretty keyboard icon for all keyboard shortcuts. How can I do this?

The code snippet below is the function I currently used to convert Markdown string into HTML.

  def markdown_to_html(markdown_str)
    options = {
      filter_html: true,
      link_attributes: { rel: 'nofollow', target: '_blank' },
      no_styles: true
    }

    extensions = {
      autolink: true,
      fenced_code_blocks: true,
      footnotes: true,
      highlight: true,
      no_intra_emphasis: true,
      quote: true,
      space_after_headers: true,
      strikethrough: true,
      superscript: true,
      tables: true
    }

    renderer = Redcarpet::Render::HTML.new(options)
    markdown = Redcarpet::Markdown.new(renderer, extensions)

    markdown.render(markdown_str).html_safe
  end

Use sanitize and your own custom scrubber class.

This class can go in the same file as your controller class.

class MarkdownScrubber < Rails::Html::PermitScrubber
  def initialize
    super
    self.tags = %w( kbd )
    self.attributes = []
  end

  def skip_node?(node)
    node.text?
  end
end

Then use that when you call render:

renderer = Redcarpet::Render::HTML.new(options)
markdown = Redcarpet::Markdown.new(renderer, extensions)
sanitize(markdown.render(markdown_str), scrubber: MarkdownScrubber.new)