Medusa: a ruby crawler framework

Medusa is a framework for the ruby language to crawl and collect useful information about the pages it visits. It is versatile, allowing you to write your own specialized tasks quickly and easily.

Features

• Choose the links to follow on each page with focus_crawl

• Multi-threaded design for high performance

• Tracks 301 HTTP redirects

• Allows exclusion of URLs based on regular expressions

• Records response time for each page

• Obey robots.txt directives (optional, but recommended)

• In-memory or persistent storage of pages during crawl, provided by Moneta

• Inherits OpenURI behavior (redirects, automatic charset and encoding detection, proxy configuration options).

Do you have an idea or a suggestion? {Open an issue and talk about it}[https://github.com/brutuscat/medusa-crawler/issues/new]

Examples

Medusa is versatile and to be used programatically, you can start with one or multiple URIs:

require 'medusa'

Medusa.crawl('https://www.example.com', depth_limit: 2)

Or you can pass a block and it will yield the crawler back, to manage configuration or drive its crawling focus:

require 'medusa'

Medusa.crawl('https://www.example.com', depth_limit: 2) do |crawler|
  crawler.discard_page_bodies = some_flag

  # Persist all the pages state across crawl-runs.
  crawler.clear_on_startup = false
  crawler.storage = Medusa::Storage.Moneta(:Redis, 'redis://redis.host.name:6379/0')

  crawler.skip_links_like(/private/)

  crawler.on_pages_like(/public/) do |page|
    logger.debug "[public page]  #{page.url} took #{page.response_time} found #{page.links.count}"
  end

  # Use an arbitrary logic, page by page, to continue customize the crawling.
  crawler.focus_crawl(/public/) do |page|
    page.links.first
  end
end

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Requirements

moneta

for the key/value storage adapters

nokogiri

for parsing the HTML of webpages

robotex

for support of the robots.txt directives

Development

To test and develop this gem, additional requirements are:

• rspec

• webmock

About

Medusa is a revamped version of the defunk anemone gem.

License

Copyright © 2009 Vertive, Inc.

Copyright © 2020 Mauro Asprea

Released under the MIT License