Kimurai

Kimurai is a modern web scraping framework written in Ruby which works out of box with Headless Chromium/Firefox, PhantomJS, or simple HTTP requests and allows to scrape and interact with JavaScript rendered websites.

Kimurai based on well-known Capybara and Nokogiri gems, so you don't have to learn anything new. Lets see:

# github_crawler.rb

require 'kimurai'
require 'kimurai/all'

class GithubCrawler < Kimurai::Base
  @name = "github_crawler"
  @driver = :selenium_chrome
  @start_urls = ["https://github.com/search?q=Ruby%20Web%20Scraping"]

  def parse(response, url:, data: {})
    response.xpath("//ul[@class='repo-list']/div//h3/a").each do |a|
      request_to :parse_repo_page, url: absolute_url(a[:href], base: url)
    end

    if next_page = response.at_xpath("//a[@class='next_page']")
      request_to :parse, url: absolute_url(next_page[:href], base: url)
    end
  end

  def parse_repo_page(response, url:, data: {})
    item = {}

    item[:owner] = response.xpath("//h1//a[@rel='author']").text
    item[:repo_name] = response.xpath("//h1/strong[@itemprop='name']/a").text
    item[:repo_url] = url
    item[:description] = response.xpath("//span[@itemprop='about']").text.squish
    item[:tags] = response.xpath("//div[@id='topics-list-container']/div/a").map { |a| a.text.squish }
    item[:watch_count] = response.xpath("//ul[@class='pagehead-actions']/li[contains(., 'Watch')]/a[2]").text.squish
    item[:star_count] = response.xpath("//ul[@class='pagehead-actions']/li[contains(., 'Star')]/a[2]").text.squish
    item[:fork_count] = response.xpath("//ul[@class='pagehead-actions']/li[contains(., 'Fork')]/a[2]").text.squish
    item[:last_commit] = response.xpath("//span[@itemprop='dateModified']/*").text

    save_to "results.json", item, format: :pretty_json
  end
end

GithubCrawler.start!

Run: $ ruby github_crawler.rb

D, [2018-08-04 13:06:47 +0400#24700] [Main: 47383751083520] DEBUG -- github_crawler: Session builder: driver gem required: selenium
D, [2018-08-04 13:06:47 +0400#24700] [Main: 47383751083520] DEBUG -- github_crawler: Session builder: created session instance
I, [2018-08-04 13:06:47 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Session: started get request to: https://github.com/search?q=Ruby%20Web%20Scraping
D, [2018-08-04 13:06:47 +0400#24700] [Main: 47383751083520] DEBUG -- github_crawler: Session builder: enabled native headless mode for selenium_chrome
D, [2018-08-04 13:06:47 +0400#24700] [Main: 47383751083520] DEBUG -- github_crawler: Session builder: created driver instance (selenium_chrome)
I, [2018-08-04 13:06:48 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Session: a new session driver has been created: driver name: selenium_chrome, pid: 24734, port: 9515
I, [2018-08-04 13:07:00 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Session: finished get request to: https://github.com/search?q=Ruby%20Web%20Scraping
I, [2018-08-04 13:07:00 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Stats visits: requests: 1, responses: 1
D, [2018-08-04 13:07:00 +0400#24700] [Main: 47383751083520] DEBUG -- github_crawler: Session: current_memory: 163832
I, [2018-08-04 13:07:01 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Session: started get request to: https://github.com/lorien/awesome-web-scraping
I, [2018-08-04 13:07:05 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Session: finished get request to: https://github.com/lorien/awesome-web-scraping
I, [2018-08-04 13:07:05 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Stats visits: requests: 2, responses: 2
D, [2018-08-04 13:07:05 +0400#24700] [Main: 47383751083520] DEBUG -- github_crawler: Session: current_memory: 270462
I, [2018-08-04 13:07:05 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Session: started get request to: https://github.com/jaimeiniesta/metainspector
...
I, [2018-08-04 13:09:23 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Session: started get request to: https://github.com/preston/idclight
I, [2018-08-04 13:09:23 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Session: finished get request to: https://github.com/preston/idclight
I, [2018-08-04 13:09:23 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Stats visits: requests: 137, responses: 137
D, [2018-08-04 13:09:23 +0400#24700] [Main: 47383751083520] DEBUG -- github_crawler: Session: current_memory: 280797
I, [2018-08-04 13:09:23 +0400#24700] [Main: 47383751083520]  INFO -- github_crawler: Crawler: stopped: {:crawler_name=>"github_crawler", :status=>:completed, :environment=>"development", :start_time=>2018-08-04 13:06:47 +0400, :stop_time=>2018-08-04 13:09:23 +0400, :running_time=>"2m, 36s", :session_id=>nil, :visits=>{:requests=>137, :responses=>137, :requests_errors=>{}}, :error=>nil, :server=>{:hostname=>"my-pc", :ipv4=>"192.168.0.2", :process_pid=>24700}}

results.json

[
  {
    "owner": "lorien",
    "repo_name": "awesome-web-scraping",
    "repo_url": "https://github.com/lorien/awesome-web-scraping",
    "description": "List of libraries, tools and APIs for web scraping and data processing.",
    "tags": [
      "awesome",
      "awesome-list",
      "web-scraping",
      "data-processing",
      "python",
      "javascript",
      "php",
      "ruby"
    ],
    "watch_count": "161",
    "star_count": "2,400",
    "fork_count": "348",
    "last_commit": "19 days ago",
    "position": 1
  },
  ...
  {
    "owner": "preston",
    "repo_name": "idclight",
    "repo_url": "https://github.com/preston/idclight",
    "description": "A Ruby gem for accessing the freely available IDClight (IDConverter Light) web service, which convert between different types of gene IDs such as Hugo and Entrez. Queries are screen scraped from http://idclight.bioinfo.cnio.es.",
    "tags": [

    ],
    "watch_count": "6",
    "star_count": "1",
    "fork_count": "0",
    "last_commit": "on Apr 12, 2012",
    "position": 124
  }
]

Okay, that was easy. How about javascript rendered websites with dynamic HTML? Lets scrape a page with infinite scroll:

# infinite_scroll_crawler.rb

require 'kimurai'
require 'kimurai/all'

class InfiniteScrollCrawler < Kimurai::Base
  @name = "infinite_scroll_crawler"
  @driver = :selenium_chrome
  @start_urls = ["https://infinite-scroll.com/demo/full-page/"]

  def parse(response, url:, data: {})
    posts_headers_path = "//article/h2"
    count = response.xpath(posts_headers_path).count

    loop do
      browser.execute_script("window.scrollBy(0,10000)") ; sleep 2
      response = browser.current_response

      new_count = response.xpath(posts_headers_path).count
      if count == new_count
        logger.info "> Pagination is done" and break
      else
        count = new_count
        logger.info "> Continue scrolling, current count is #{count}..."
      end
    end

    posts_headers = response.xpath(posts_headers_path).map(&:text)
    logger.info "> All posts from page: #{posts_headers.join('; ')}"
  end
end

InfiniteScrollCrawler.start!

Run: $ ruby infinite_scroll_crawler.rb

D, [2018-08-04 17:54:14 +0400#29308] [Main: 47115312711160] DEBUG -- infinite_scroll_crawler: Session builder: driver gem required: selenium
D, [2018-08-04 17:54:14 +0400#29308] [Main: 47115312711160] DEBUG -- infinite_scroll_crawler: Session builder: created session instance
I, [2018-08-04 17:54:14 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: Session: started get request to: https://infinite-scroll.com/demo/full-page/
D, [2018-08-04 17:54:14 +0400#29308] [Main: 47115312711160] DEBUG -- infinite_scroll_crawler: Session builder: enabled native headless mode for selenium_chrome
D, [2018-08-04 17:54:14 +0400#29308] [Main: 47115312711160] DEBUG -- infinite_scroll_crawler: Session builder: created driver instance (selenium_chrome)
I, [2018-08-04 17:54:14 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: Session: a new session driver has been created: driver name: selenium_chrome, pid: 29342, port: 9515
I, [2018-08-04 17:54:18 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: Session: finished get request to: https://infinite-scroll.com/demo/full-page/
I, [2018-08-04 17:54:18 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: Stats visits: requests: 1, responses: 1
D, [2018-08-04 17:54:18 +0400#29308] [Main: 47115312711160] DEBUG -- infinite_scroll_crawler: Session: current_memory: 145957
I, [2018-08-04 17:54:21 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: > Continue scrolling, current count is 5...
I, [2018-08-04 17:54:28 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: > Continue scrolling, current count is 9...
I, [2018-08-04 17:54:34 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: > Continue scrolling, current count is 11...
I, [2018-08-04 17:54:40 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: > Continue scrolling, current count is 13...
I, [2018-08-04 17:54:43 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: > Continue scrolling, current count is 15...
I, [2018-08-04 17:54:45 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: > Pagination is done
I, [2018-08-04 17:54:45 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: > All posts from page: 1a - Infinite Scroll full page demo; 1b - RGB Schemes logo in Computer Arts; 2a - RGB Schemes logo; 2b - Masonry gets horizontalOrder; 2c - Every vector 2016; 3a - Logo Pizza delivered; 3b - Some CodePens; 3c - 365daysofmusic.com; 3d - Holograms; 4a - Huebee: 1-click color picker; 4b - Word is Flickity is good; Flickity v2 released: groupCells, adaptiveHeight, parallax; New tech gets chatter; Isotope v3 released: stagger in, IE8 out; Packery v2 released
I, [2018-08-04 17:54:45 +0400#29308] [Main: 47115312711160]  INFO -- infinite_scroll_crawler: Crawler: stopped: {:crawler_name=>"infinite_scroll_crawler", :status=>:completed, :environment=>"development", :start_time=>2018-08-04 17:54:14 +0400, :stop_time=>2018-08-04 17:54:45 +0400, :running_time=>"31s", :session_id=>nil, :visits=>{:requests=>1, :responses=>1, :requests_errors=>{}}, :error=>nil, :server=>{:hostname=>"my-pc", :ipv4=>"192.168.0.2", :process_pid=>29308}}

Features

• Scrape javascript rendered websites out of box
• Supported drivers: Headless Chrome, Headless Firefox, PhantomJS or simple HTTP requests (mechanize gem)
• Write crawler code once, and use it with any supported driver later
• All the power of Capybara: use methods like click_on, fill_in, select, choose, set, go_back, etc. to interact with web pages
• Rich configuration: set default headers, cookies, delay between requests, enable proxy/user-agents rotation
• Built-in helpers to make scraping easy, like save_to (save items to JSON, JSON lines, CSV or YAML formats) or unique? to skip duplicates
• Automatically retry failed requests with delay
• Automatically restart browsers when reaching memory limit (memory control) or requests limit
• Easily schedule crawlers within cron using Whenever (no need to know cron syntax)
• Parallel crawling using simple method in_parallel
• Two modes: use single file for a simple crawler, or generate Scrapy-like project
• Convenient development mode with console, colorized logger and debugger (Pry, Byebug)
• Automated server environment setup (for ubuntu 18.04) and deploy using commands kimurai setup and kimurai deploy (Ansible under the hood)
• Command-line runner to run all project crawlers one by one or in parallel
• Stats database with web dashboard

Table of Contents

• Kimurai
  • Features
  • Table of Contents
  • Installation
  • Getting to Know
    • Interactive console
    • Available drivers
    • Minimum required crawler structure
    • Method arguments response, url and data
    • browser object
    • request_to method
    • save_to helper
    • Skip duplicates, unique? helper
    • at_start and at_stop callbacks
    • KIMURAI_ENV
    • Parallel crawling using in_parallel
    • Active Support included
    • Schedule crawlers using Cron
    • Configuration options
    • Automated sever setup and deployment
      • Setup
      • Deploy
  • Crawler @config
    • All available @config options
    • @config settings inheritance
  • Project mode
    • Generate new crawler
    • Start
    • List
    • Parse
    • Pipelines, send_item method
    • Runner
      • Runner (session) callbacks
    • Stats database + dashboard
  • Chat Support and Feedback
  • Author
  • License

Installation

Kimurai requires Ruby version >= 2.5.0. Supported platforms: Linux and Mac OS X.

1. If your system doesn't have appropriate Ruby version, install it:

Ubuntu 18.04

# Install required packages for ruby-build
sudo apt update
sudo apt install git-core curl zlib1g-dev build-essential libssl-dev libreadline-dev libreadline6-dev libyaml-dev libxml2-dev libxslt1-dev libcurl4-openssl-dev libffi-dev

# Install rbenv and ruby-build
cd && git clone https://github.com/rbenv/rbenv.git ~/.rbenv
echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(rbenv init -)"' >> ~/.bashrc
exec $SHELL

git clone https://github.com/rbenv/ruby-build.git ~/.rbenv/plugins/ruby-build
echo 'export PATH="$HOME/.rbenv/plugins/ruby-build/bin:$PATH"' >> ~/.bashrc
exec $SHELL

# Install latest Ruby
rbenv install 2.5.1
rbenv global 2.5.1

gem install bundler

Mac OS X

# Install homebrew if you don't have it https://brew.sh/
# Install rbenv and ruby-build:
brew install rbenv ruby-build

# Add rbenv to bash so that it loads every time you open a terminal
echo 'if which rbenv > /dev/null; then eval "$(rbenv init -)"; fi' >> ~/.bash_profile
source ~/.bash_profile

# Install latest Ruby
rbenv install 2.5.1
rbenv global 2.5.1

gem install bundler

2. Install Kimurai gem: $ gem install kimurai

3. Install browsers with webdrivers:

Ubuntu 18.04

Note: for Ubuntu 16.04-18.04 there is available automatic installation using setup command:

$ kimurai setup localhost --local --ask-sudo

It works using Ansible so you need to install it first: $ sudo apt install ansible. You can check using playbooks here.

If you chose automatic installation, you can skip following and go to "Getting To Know" part. In case if you want to install everything manually:

# Install basic tools
sudo apt install -q -y unzip wget tar openssl

# Install xvfb (for virtual_display headless mode, in additional to native)
sudo apt install -q -y xvfb

# Install chromium-browser and firefox
sudo apt install -q -y chromium-browser firefox

# Instal chromedriver (2.39 version)
# All versions located here https://sites.google.com/a/chromium.org/chromedriver/downloads
cd /tmp && wget https://chromedriver.storage.googleapis.com/2.39/chromedriver_linux64.zip
sudo unzip chromedriver_linux64.zip -d /usr/local/bin
rm -f chromedriver_linux64.zip

# Install geckodriver (0.21.0 version)
# All versions located here https://github.com/mozilla/geckodriver/releases/
cd /tmp && wget https://github.com/mozilla/geckodriver/releases/download/v0.21.0/geckodriver-v0.21.0-linux64.tar.gz
sudo tar -xvzf geckodriver-v0.21.0-linux64.tar.gz -C /usr/local/bin
rm -f geckodriver-v0.21.0-linux64.tar.gz

# Install PhantomJS (2.1.1)
# All versions located here http://phantomjs.org/download.html
sudo apt install -q -y chrpath libxft-dev libfreetype6 libfreetype6-dev libfontconfig1 libfontconfig1-dev
cd /tmp && wget https://bitbucket.org/ariya/phantomjs/downloads/phantomjs-2.1.1-linux-x86_64.tar.bz2
tar -xvjf phantomjs-2.1.1-linux-x86_64.tar.bz2
sudo mv phantomjs-2.1.1-linux-x86_64 /usr/local/lib
sudo ln -s /usr/local/lib/phantomjs-2.1.1-linux-x86_64/bin/phantomjs /usr/local/bin
rm -f phantomjs-2.1.1-linux-x86_64.tar.bz2

Mac OS X

# Install chrome and firefox
brew cask install google-chrome firefox

# Install chromedriver (latest)
brew cask install chromedriver

# Install geckodriver (latest)
brew install geckodriver

# Install PhantomJS (latest)
brew install phantomjs

Also, you'll probably want to save scraped items to the database (using ActiveRecord, Sequel or MongoDB Ruby Driver/Mongoid). For this you need to install database clients/servers:

Ubuntu 18.04

SQlite: $ sudo apt -q -y install libsqlite3-dev sqlite3.

If you want to connect to a remote database, you don't need database server on local machine, only client:

# Install MySQL client
sudo apt -q -y install mysql-client libmysqlclient-dev

# Install Postgres client
sudo apt install -q -y postgresql-client libpq-dev

# Install MongoDB client
sudo apt install -q -y mongodb-clients

But if you want to save items to a local database, server required as well:

# Install MySQL client and server
sudo apt -q -y install mysql-server mysql-client libmysqlclient-dev

# Install  Postgres client and server
sudo apt install -q -y postgresql postgresql-contrib libpq-dev

# Install MongoDB client and server
# version 4.0 (check here https://docs.mongodb.com/manual/tutorial/install-mongodb-on-ubuntu/)
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 9DA31620334BD75D9DCB49F368818C72E52529D4
# for 16.04:
# echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/4.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.0.list
# for 18.04:
echo "deb [ arch=amd64 ] https://repo.mongodb.org/apt/ubuntu bionic/mongodb-org/4.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.0.list
sudo apt update
sudo apt install -q -y mongodb-org
sudo service mongod start

Mac OS X

SQlite: $ brew install sqlite3

# Install MySQL client and server
brew install mysql
# Start server if you need it: brew services start mysql

# Install Postgres client and server
brew install postgresql
# Start server if you need it: brew services start postgresql

# Install MongoDB client and server
brew install mongodb
# Start server if you need it: brew services start mongodb

Getting to Know

Interactive console

Before you get to know all Kimurai features, there is $ kimurai console command which is an interactive console where you can try and debug your scraping code very quickly, without having to run any crawler (yes, it's like Scrapy shell).

$ kimurai console --driver selenium_chrome --url https://github.com/vfreefly/kimurai

Show output

$ kimurai console --driver selenium_chrome --url https://github.com/vfreefly/kimurai

D, [2018-08-07 22:55:39 +0400#28225] [Main: 46928107103740] DEBUG -- : Session builder: driver gem required: selenium
D, [2018-08-07 22:55:39 +0400#28225] [Main: 46928107103740] DEBUG -- : Session builder: created session instance
I, [2018-08-07 22:55:39 +0400#28225] [Main: 46928107103740]  INFO -- : Session: started get request to: https://github.com/vfreefly/kimurai
D, [2018-08-07 22:55:39 +0400#28225] [Main: 46928107103740] DEBUG -- : Session builder: enabled native headless mode for selenium_chrome
D, [2018-08-07 22:55:39 +0400#28225] [Main: 46928107103740] DEBUG -- : Session builder: created driver instance (selenium_chrome)
I, [2018-08-07 22:55:39 +0400#28225] [Main: 46928107103740]  INFO -- : Session: a new session driver has been created: driver name: selenium_chrome, pid: 28261, port: 9515
I, [2018-08-07 22:55:42 +0400#28225] [Main: 46928107103740]  INFO -- : Session: finished get request to: https://github.com/vfreefly/kimurai
I, [2018-08-07 22:55:42 +0400#28225] [Main: 46928107103740]  INFO -- : Stats visits: requests: 1, responses: 1
D, [2018-08-07 22:55:42 +0400#28225] [Main: 46928107103740] DEBUG -- : Session: current_memory: 258068

    181: def console(response = nil, url: nil, data: {})
 => 182:   binding.pry
    183: end

[1] pry(#<Kimurai::Base>)> response.xpath("//title").text
=> "GitHub - vfreefly/kimurai: Kimurai is a modern web scraping framework written in Ruby which works out of box with headless chromium/firefox, phantomjs, or simple HTTP requests and allows to scrape and interact with javascript rendered websites"

[2] pry(#<Kimurai::Base>)> ls
Kimurai::Base#methods: browser  console  request_to
instance variables: @browser  @config  @driver  @pipelines
locals: _  __  _dir_  _ex_  _file_  _in_  _out_  _pry_  data  response  url

[3] pry(#<Kimurai::Base>)> ls response
Nokogiri::XML::PP::Node#methods: inspect  pretty_print
Nokogiri::XML::Searchable#methods: %  /  at  at_css  at_xpath  css  search  xpath
Enumerable#methods:
  all?         collect         drop        each_with_index   find_all    grep_v    lazy    member?    none?      reject        slice_when  take_while  without
  any?         collect_concat  drop_while  each_with_object  find_index  group_by  many?   min        one?       reverse_each  sort        to_a        zip
  as_json      count           each_cons   entries           first       include?  map     min_by     partition  select        sort_by     to_h
  chunk        cycle           each_entry  exclude?          flat_map    index_by  max     minmax     pluck      slice_after   sum         to_set
  chunk_while  detect          each_slice  find              grep        inject    max_by  minmax_by  reduce     slice_before  take        uniq
Nokogiri::XML::Node#methods:
  <=>                   append_class       classes                 document?             has_attribute?      matches?          node_name=        processing_instruction?  to_str
  ==                    attr               comment?                each                  html?               name=             node_type         read_only?               to_xhtml
  >                     attribute          content                 elem?                 inner_html          namespace=        parent=           remove                   traverse
  []                    attribute_nodes    content=                element?              inner_html=         namespace_scopes  parse             remove_attribute         unlink
  []=                   attribute_with_ns  create_external_subset  element_children      inner_text          namespaced_key?   path              remove_class             values
  accept                before             create_internal_subset  elements              internal_subset     native_content=   pointer_id        replace                  write_html_to
  add_class             blank?             css_path                encode_special_chars  key?                next              prepend_child     set_attribute            write_to
  add_next_sibling      cdata?             decorate!               external_subset       keys                next=             previous          text                     write_xhtml_to
  add_previous_sibling  child              delete                  first_element_child   lang                next_element      previous=         text?                    write_xml_to
  after                 children           description             fragment?             lang=               next_sibling      previous_element  to_html                  xml?
  ancestors             children=          do_xinclude             get_attribute         last_element_child  node_name         previous_sibling  to_s
Nokogiri::XML::Document#methods:
  <<         canonicalize  collect_namespaces  create_comment  create_entity     decorate    document  encoding   errors   name        remove_namespaces!  root=  to_java  url       version
  add_child  clone         create_cdata        create_element  create_text_node  decorators  dup       encoding=  errors=  namespaces  root                slop!  to_xml   validate
Nokogiri::HTML::Document#methods: fragment  meta_encoding  meta_encoding=  meta_robots  nofollow?  noindex?  serialize  title  title=  type
instance variables: @decorators  @errors  @node_cache

[4] pry(#<Kimurai::Base>)> exit
$

CLI options:

• --driver (optional) driver to use. Default is mechanize
• --url (optional) url to process. If url omitted, response and url objects inside the console will be nil (use browser object to navigate to any webpage).

Available drivers

Kimurai has support for following drivers and mostly can switch between them without need to rewrite any code:

• :mechanize - pure Ruby fake http browser. Mechanize can't render javascript and don't know what DOM is it. It only can parse original HTML code of a page. Because of it, mechanize much faster, takes much less memory and in general much more stable than any real browser. Use mechanize if you can do it, and the website doesn't use javascript to render any meaningful parts of its structure. Still, because mechanize trying to mimic a real browser, it supports almost all Capybara's methods to interact with a web page (filling forms, clicking buttons, checkboxes, etc).
• :poltergeist_phantomjs - PhantomJS headless browser, can render javascript. In general, PhantomJS still faster than Headless Chrome (and headless firefox). PhantomJS has memory leakage, but Kimurai has memory control feature so you shouldn't consider it as a problem. Also, some websites can recognize PhantomJS and block access to them. Like mechanize (and unlike selenium drivers) :poltergeist_phantomjs can freely rotate proxies and change headers on the fly (see config section).
• :selenium_chrome Chrome in headless mode driven by selenium. Modern headless browser solution with proper javascript rendering.
• :selenium_firefox Firefox in headless mode driven by selenium. Usually takes more memory than other drivers, but sometimes can be useful.

Tip: add HEADLESS=false env variable before command ($ HEADLESS=false ruby crawler.rb) to run browser in normal (not headless) mode and see it's window (only for selenium-like drivers). It works for console command as well.

Minimum required crawler structure

require 'kimurai'
require 'kimurai/all'

class SimpleCrawler < Kimurai::Base
  @name = "simple_crawler"
  @driver = :selenium_chrome
  @start_urls = ["https://example.com/"]

  def parse(response, url:, data: {})
  end
end

SimpleCrawler.start!

Where:

• @name name of crawler. You can omit name if use single file crawler
• @driver driver for crawler
• @start_urls array of start urls to process one by one inside parse method
• Method parse is the start method, should be always present in crawler class

Method arguments response, url and data

def parse(response, url:, data: {})
end

• response (Nokogiri::HTML::Document object) Contains parsed HTML code of processed webpage
• url (String) url of processed webpage
• data (Hash) uses to pass data between requests

Example how to use data

Imagine that there is a product page which doesn't contain product category. Category name present only on category page with pagination. This is the case where we can use data to pass category name from parse to parse_product method:

class ProductsCrawler < Kimurai::Base
  @driver = :selenium_chrome
  @start_urls = ["https://example-shop.com/example-product-category"]

  def parse(response, url:, data: {})
    category_name = response.xpath("//path/to/category/name").text

    response.xpath("//path/to/products/urls").each do |product_url|
      # merge category_name with current data hash and pass it next to parse_product method
      request_to(:parse_product, url: product_url[:href], data: data.merge(category_name: category_name))
    end

    # ...
  end

  def parse_product(response, url:, data: {})
    item = {}
    # assign item's category_name from data[:category_name]
    item[:category_name] = data[:category_name]

    # ...
  end
end

You can query response using XPath or CSS selectors. Check Nokogiri tutorials to understand how to work with response:

• Parsing HTML with Nokogiri - ruby.bastardsbook.com
• HOWTO parse HTML with Ruby & Nokogiri - readysteadycode.com
• Class: Nokogiri::HTML::Document (documentation) - rubydoc.info

browser object

From any crawler instance method there is available browser object, which is Capybara::Session object and uses to process requests and get page response (current_response method). Usually you don't need to touch it directly, because there is response (see above) which contains page response after it was loaded.

But if you need to interact with a page (like filling form fields, clicking elements, checkboxes, etc) browser is ready for you:

class GoogleCrawler < Kimurai::Base
  @name = "google_crawler"
  @driver = :selenium_chrome
  @start_urls = ["https://www.google.com/"]

  def parse(response, url:, data: {})
    browser.fill_in "q", with: "Kimurai web scraping framework"
    browser.click_button "Google Search"

    # Update response to current response after interaction with browser
    response = browser.current_response

    # collect results
    results = response.xpath("//div[@class='g']//h3/a").map do |a|
      { title: a.text, url: a[:href] }
    end

    # ...
  end
end

Check out Capybara cheat sheets where you can see all available methods to interact with browser:

• UI Testing with RSpec and Capybara [cheat sheet] - cheatrags.com
• Capybara Cheatsheet PDF - thoughtbot.com
• Class: Capybara::Session (documentation) - rubydoc.info

request_to method

For making requests to a particular method there is request_to. It requires minimum two arguments: :method_name and url:. An optional argument is data: (see above what for is it). Example:

class Crawler < Kimurai::Base
  @driver = :selenium_chrome
  @start_urls = ["https://example.com/"]

  def parse(response, url:, data: {})
    request_to :parse_product, url: "https://example.com/some_product"
  end

  def parse_product(response, url:, data: {})
    puts "from page https://example.com/some_product !"
  end
end

Under the hood request_to simply call #visit (browser.visit(url)) and then required method with arguments:

request_to

def request_to(handler, url:, data: {})
  request_data = { url: url, data: data }

  browser.visit(url)
  public_send(handler, browser.current_response, request_data)
end

request_to just makes things simpler, and without it we could do something like:

Check the code

class Crawler < Kimurai::Base
  @driver = :selenium_chrome
  @start_urls = ["https://example.com/"]

  def parse(response, url:, data: {})
    url_to_process = "https://example.com/some_product"

    browser.visit(url_to_process)
    parse_product(browser.current_response, url: url_to_process)
  end

  def parse_product(response, url:, data: {})
    puts "from page https://example.com/some_product !"
  end
end

save_to helper

Sometimes all that you need is to simply save scraped data to a file format, like JSON or CSV. You can use save_to for it:

class ProductsCrawler < Kimurai::Base
  @driver = :selenium_chrome
  @start_urls = ["https://example-shop.com/"]

  # ...

  def parse_product(response, url:, data: {})
    item = {}

    item[:title] = response.xpath("//title/path").text
    item[:description] = response.xpath("//desc/path").text.squish
    item[:price] = response.xpath("//price/path").text[/\d+/]&.to_f

    # add each new item to `scraped_products.json` file
    save_to "scraped_products.json", item, format: :json
  end
end

Supported formats:

• :yaml YAML
• :json JSON
• :pretty_json "pretty" JSON (JSON.pretty_generate)
• :jsonlines JSON Lines
• :csv CSV

Note: save_to requires data (item to save) to be a Hash.

By default save_to add position key to an item hash. You can disable it with position: false: save_to "scraped_products.json", item, format: :json, position: false.

How helper works:

Until crawler stops, each new item will be appended to a file. At the next run, helper will clear the content of a file first, and then start again appending items to it.

Skip duplicates, unique? helper

It's pretty common when websites have duplicated pages. For example when an e-commerce shop has the same products in different categories. To skip duplicates, there is unique? helper:

class ProductsCrawler < Kimurai::Base
  @driver = :selenium_chrome
  @start_urls = ["https://example-shop.com/"]

  def parse(response, url:, data: {})
    response.xpath("//categories/path").each do |category|
      request_to :parse_category, url: category[:href]
    end
  end

  # check products for uniqueness using product url inside of parse_category
  def parse_category(response, url:, data: {})
    response.xpath("//products/path").each do |product|
      # skip url if it's not unique
      next unless unique?(product_url: product[:href])
      # otherwise process it
      request_to :parse_product, url: product[:href]
    end
  end

  # or/and check products for uniqueness using product stock number inside of parse_product
  def parse_product(response, url:, data: {})
    item = {}
    item[:stock_number] = response.xpath("//product/stock_number/path").text.strip.upcase
    # don't save product and return from method if there is already saved item with same stock_number
    return unless unique?(stock_number: item[:stock_number])

    # ...
    save_to "results.json", item, format: :json
  end
end

unique? helper works pretty simple:

# check string "http://example.com" in scope `url` for a first time:
unique?(url: "http://example.com")
# => true

# try again:
unique?(url: "http://example.com")
# => false

To check something for uniqueness, you need to provide a scope:

# `product_url` scope
unique?(product_url: "http://example.com/product_1")

# `id` scope
unique?(id: 324234232)

# `custom` scope
unique?(custom: "Lorem Ipsum")

at_start and at_stop callbacks

You can define .at_start and .at_stop callbacks (class methods) to perform some action before crawler started or after crawler has been stopped:

require 'kimurai'
require 'kimurai/all'

class Crawler < Kimurai::Base
  @name = "example_crawler"
  @driver = :selenium_chrome
  @start_urls = ["https://example.com/"]

  def self.at_start
    logger.info "> Starting..."
  end

  def self.at_stop
    logger.info "> Stopped!"
  end

  def parse(response, url:, data: {})
    logger.info "> Scraping..."
  end
end

Crawler.start!

Output

I, [2018-08-05 23:14:55 +0400#15800] [Main: 47044281271800]  INFO -- example_crawler: > Starting...
D, [2018-08-05 23:14:55 +0400#15800] [Main: 47044281271800] DEBUG -- example_crawler: Session builder: driver gem required: selenium
D, [2018-08-05 23:14:55 +0400#15800] [Main: 47044281271800] DEBUG -- example_crawler: Session builder: created session instance
I, [2018-08-05 23:14:55 +0400#15800] [Main: 47044281271800]  INFO -- example_crawler: Session: started get request to: https://example.com/
D, [2018-08-05 23:14:55 +0400#15800] [Main: 47044281271800] DEBUG -- example_crawler: Session builder: enabled native headless mode for selenium_chrome
D, [2018-08-05 23:14:55 +0400#15800] [Main: 47044281271800] DEBUG -- example_crawler: Session builder: created driver instance (selenium_chrome)
I, [2018-08-05 23:14:55 +0400#15800] [Main: 47044281271800]  INFO -- example_crawler: Session: a new session driver has been created: driver name: selenium_chrome, pid: 15840, port: 9515
I, [2018-08-05 23:14:56 +0400#15800] [Main: 47044281271800]  INFO -- example_crawler: Session: finished get request to: https://example.com/
I, [2018-08-05 23:14:56 +0400#15800] [Main: 47044281271800]  INFO -- example_crawler: Stats visits: requests: 1, responses: 1
D, [2018-08-05 23:14:56 +0400#15800] [Main: 47044281271800] DEBUG -- example_crawler: Session: current_memory: 129448
I, [2018-08-05 23:14:56 +0400#15800] [Main: 47044281271800]  INFO -- example_crawler: > Scraping...
I, [2018-08-05 23:14:56 +0400#15800] [Main: 47044281271800]  INFO -- example_crawler: Crawler: stopped: {:crawler_name=>"example_crawler", :status=>:completed, :environment=>"development", :start_time=>2018-08-05 23:14:55 +0400, :stop_time=>2018-08-05 23:14:56 +0400, :running_time=>"1s", :session_id=>nil, :visits=>{:requests=>1, :responses=>1, :requests_errors=>{}}, :error=>nil, :server=>{:hostname=>"my-pc", :ipv4=>"192.168.0.2", :process_pid=>15800}}
I, [2018-08-05 23:14:56 +0400#15800] [Main: 47044281271800]  INFO -- example_crawler: > Stopped!

Inside at_start and at_stop class methods there is available run_info method which contains useful information about crawler state:

    11: def self.at_start
 => 12:   binding.pry
    13: end

[1] pry(example_crawler)> run_info
=> {
  :crawler_name=>"example_crawler",
  :status=>:running,
  :environment=>"development",
  :start_time=>2018-08-05 23:32:00 +0400,
  :stop_time=>nil,
  :running_time=>nil,
  :session_id=>nil,
  :visits=>{:requests=>0, :responses=>0, :requests_errors=>{}},
  :error=>nil,
  :server=>{:hostname=>"my-pc", :ipv4=>"192.168.0.2", :process_pid=>20814}
}

Inside at_stop, run_info will be updated:

    15: def self.at_stop
 => 16:   binding.pry
    17: end

[1] pry(example_crawler)> run_info
=> {
  :crawler_name=>"example_crawler",
  :status=>:completed,
  :environment=>"development",
  :start_time=>2018-08-05 23:32:00 +0400,
  :stop_time=>2018-08-05 23:32:06 +0400,
  :running_time=>6.214,
  :session_id=>nil,
  :visits=>{:requests=>1, :responses=>1, :requests_errors=>{}},
  :error=>nil,
  :server=>{:hostname=>"my-pc", :ipv4=>"192.168.0.2", :process_pid=>20814}
}

run_info[:status] helps to determine if crawler was finished successfully or failed (possible values: :completed, :failed):

class Crawler < Kimurai::Base
  @name = "example_crawler"
  @driver = :selenium_chrome
  @start_urls = ["https://example.com/"]

  def self.at_stop
    puts ">>> run info: #{run_info}"
  end

  def parse(response, url:, data: {})
    logger.info "> Scraping..."
    # Let's try to strip nil:
    nil.strip
  end
end

Output

D, [2018-08-05 23:52:54 +0400#26484] [Main: 47111535224320] DEBUG -- example_crawler: Session builder: driver gem required: selenium
D, [2018-08-05 23:52:54 +0400#26484] [Main: 47111535224320] DEBUG -- example_crawler: Session builder: created session instance
I, [2018-08-05 23:52:54 +0400#26484] [Main: 47111535224320]  INFO -- example_crawler: Session: started get request to: https://example.com/
D, [2018-08-05 23:52:54 +0400#26484] [Main: 47111535224320] DEBUG -- example_crawler: Session builder: enabled native headless mode for selenium_chrome
D, [2018-08-05 23:52:54 +0400#26484] [Main: 47111535224320] DEBUG -- example_crawler: Session builder: created driver instance (selenium_chrome)
I, [2018-08-05 23:52:54 +0400#26484] [Main: 47111535224320]  INFO -- example_crawler: Session: a new session driver has been created: driver name: selenium_chrome, pid: 26516, port: 9515
I, [2018-08-05 23:52:55 +0400#26484] [Main: 47111535224320]  INFO -- example_crawler: Session: finished get request to: https://example.com/
I, [2018-08-05 23:52:55 +0400#26484] [Main: 47111535224320]  INFO -- example_crawler: Stats visits: requests: 1, responses: 1
D, [2018-08-05 23:52:55 +0400#26484] [Main: 47111535224320] DEBUG -- example_crawler: Session: current_memory: 129015
I, [2018-08-05 23:52:55 +0400#26484] [Main: 47111535224320]  INFO -- example_crawler: > Scraping...
F, [2018-08-05 23:52:55 +0400#26484] [Main: 47111535224320] FATAL -- example_crawler: Crawler: stopped: {:crawler_name=>"example_crawler", :status=>:failed, :environment=>"development", :start_time=>2018-08-05 23:52:54 +0400, :stop_time=>2018-08-05 23:52:55 +0400, :running_time=>"1s", :session_id=>nil, :visits=>{:requests=>1, :responses=>1, :requests_errors=>{}}, :error=>"#<NoMethodError: undefined method `strip' for nil:NilClass>", :server=>{:hostname=>"my-pc", :ipv4=>"192.168.0.2", :process_pid=>26484}}

>>> run info: {:crawler_name=>"example_crawler", :status=>:failed, :environment=>"development", :start_time=>2018-08-05 23:52:54 +0400, :stop_time=>2018-08-05 23:52:55 +0400, :running_time=>1.445, :session_id=>nil, :visits=>{:requests=>1, :responses=>1, :requests_errors=>{}}, :error=>"#<NoMethodError: undefined method `strip' for nil:NilClass>", :server=>{:hostname=>"my-pc", :ipv4=>"192.168.0.2", :process_pid=>26484}}

Traceback (most recent call last):
        6: from crawler.rb:22:in `<main>'
        5: from /home/victor/code/kimurai/lib/kimurai/base.rb:135:in `start!'
        4: from /home/victor/code/kimurai/lib/kimurai/base.rb:135:in `each'
        3: from /home/victor/code/kimurai/lib/kimurai/base.rb:136:in `block in start!'
        2: from /home/victor/code/kimurai/lib/kimurai/base.rb:178:in `request_to'
        1: from /home/victor/code/kimurai/lib/kimurai/base.rb:178:in `public_send'
crawler.rb:18:in `parse': undefined method `strip' for nil:NilClass (NoMethodError)

Usage example: if crawler finished successfully, send JSON file with scraped items to a remote FTP location, otherwise (if crawler failed), skip incompleted results and send email/notification to slack about it:

Show example

Also you can use additional methods completed? or failed?

class Crawler < Kimurai::Base
  @driver = :selenium_chrome
  @start_urls = ["https://example.com/"]

  def self.at_stop
    if completed?
      send_file_to_ftp("results.json")
    else
      send_error_notification(run_info[:error])
    end
  end

  def self.send_file_to_ftp(file_path)
    # ...
  end

  def self.send_error_notification(error)
    # ...
  end

  # ...

  def parse_item(response, url:, data: {})
    item = {}
    # ...

    save_to "results.json", item, format: :json
  end
end

KIMURAI_ENV

Kimurai has environments, default is development. To provide custom environment pass KIMURAI_ENV env variable before command: $ KIMURAI_ENV=production ruby crawler.rb. To access current environment from Ruby there is Kimurai.env method.

Usage example:

class Crawler < Kimurai::Base
  @driver = :selenium_chrome
  @start_urls = ["https://example.com/"]

  def self.at_stop
    if failed? && Kimurai.env == "production"
      send_error_notification(run_info[:error])
    else
      # do nothing
    end
  end

  # ...
end

Parallel crawling using in_parallel

Kimurai can process web pages concurrently in one single line: in_parallel(:parse_product, 3, urls: urls), where :parse_product is a method to process, 3 is count of threads and urls: is array of urls to crawl.

# amazon_crawler.rb

require 'kimurai'
require 'kimurai/all'

class AmazonCrawler < Kimurai::Base
  @name = "amazon_crawler"
  @driver = :mechanize
  @start_urls = ["https://www.amazon.com/"]

  def parse(response, url:, data: {})
    browser.fill_in "field-keywords", with: "Web Scraping Books"
    browser.click_on "Go"

    # walk through pagination and collect products urls:
    urls = []
    loop do
      response = browser.current_response
      response.xpath("//li//a[contains(@class, 's-access-detail-page')]").each do |a|
        urls << a[:href].sub(/ref=.+/, "")
      end

      browser.find(:xpath, "//a[@id='pagnNextLink']", wait: 1).click rescue break
    end

    # process all collected urls concurrently within 3 threads:
    in_parallel(:parse_book_page, 3, urls: urls)
  end

  def parse_book_page(response, url:, data: {})
    item = {}

    item[:title] = response.xpath("//h1/span[@id]").text.squish
    item[:url] = url
    item[:price] = response.xpath("(//span[contains(@class, 'a-color-price')])[1]").text.squish.presence
    item[:publisher] = response.xpath("//h2[text()='Product details']/following::b[text()='Publisher:']/following-sibling::text()[1]").text.squish.presence

    save_to "books.json", item, format: :pretty_json
  end
end

AmazonCrawler.start!

Run: $ ruby amazon_crawler.rb

D, [2018-08-06 12:21:48 +0400#1686] [Main: 47180432147960] DEBUG -- amazon_crawler: Session builder: driver gem required: mechanize
D, [2018-08-06 12:21:48 +0400#1686] [Main: 47180432147960] DEBUG -- amazon_crawler: Session builder: created session instance
I, [2018-08-06 12:21:48 +0400#1686] [Main: 47180432147960]  INFO -- amazon_crawler: Session: started get request to: https://www.amazon.com/
D, [2018-08-06 12:21:48 +0400#1686] [Main: 47180432147960] DEBUG -- amazon_crawler: Session builder: created driver instance (mechanize)
D, [2018-08-06 12:21:48 +0400#1686] [Main: 47180432147960] DEBUG -- amazon_crawler: Session: can't define driver_pid and driver_port for mechanize, not supported
I, [2018-08-06 12:21:48 +0400#1686] [Main: 47180432147960]  INFO -- amazon_crawler: Session: a new session driver has been created: driver name: mechanize, pid: , port:
I, [2018-08-06 12:21:54 +0400#1686] [Main: 47180432147960]  INFO -- amazon_crawler: Session: finished get request to: https://www.amazon.com/
I, [2018-08-06 12:21:54 +0400#1686] [Main: 47180432147960]  INFO -- amazon_crawler: Stats visits: requests: 1, responses: 1

I, [2018-08-06 12:21:58 +0400#1686] [Main: 47180432147960]  INFO -- amazon_crawler: Crawler: in_parallel: starting processing 53 urls within 3 threads
D, [2018-08-06 12:21:58 +0400#1686] [Child: 47180448490460] DEBUG -- amazon_crawler: Session builder: driver gem required: mechanize
D, [2018-08-06 12:21:58 +0400#1686] [Child: 47180448490460] DEBUG -- amazon_crawler: Session builder: created session instance
I, [2018-08-06 12:21:58 +0400#1686] [Child: 47180448490460]  INFO -- amazon_crawler: Session: started get request to: https://www.amazon.com/Web-Scraping-Python-Collecting-Modern/dp/1491985577/
D, [2018-08-06 12:21:58 +0400#1686] [Child: 47180448490460] DEBUG -- amazon_crawler: Session builder: created driver instance (mechanize)
D, [2018-08-06 12:21:58 +0400#1686] [Child: 47180448490460] DEBUG -- amazon_crawler: Session: can't define driver_pid and driver_port for mechanize, not supported
I, [2018-08-06 12:21:58 +0400#1686] [Child: 47180448490460]  INFO -- amazon_crawler: Session: a new session driver has been created: driver name: mechanize, pid: , port:
D, [2018-08-06 12:21:59 +0400#1686] [Child: 47180448535660] DEBUG -- amazon_crawler: Session builder: driver gem required: mechanize
D, [2018-08-06 12:21:59 +0400#1686] [Child: 47180448535660] DEBUG -- amazon_crawler: Session builder: created session instance
I, [2018-08-06 12:21:59 +0400#1686] [Child: 47180448535660]  INFO -- amazon_crawler: Session: started get request to: https://www.amazon.com/Python-Web-Scraping-Cookbook-scraping/dp/1787285219/
D, [2018-08-06 12:21:59 +0400#1686] [Child: 47180448535660] DEBUG -- amazon_crawler: Session builder: created driver instance (mechanize)
D, [2018-08-06 12:21:59 +0400#1686] [Child: 47180448535660] DEBUG -- amazon_crawler: Session: can't define driver_pid and driver_port for mechanize, not supported
I, [2018-08-06 12:21:59 +0400#1686] [Child: 47180448535660]  INFO -- amazon_crawler: Session: a new session driver has been created: driver name: mechanize, pid: , port:
D, [2018-08-06 12:22:00 +0400#1686] [Child: 47180448251660] DEBUG -- amazon_crawler: Session builder: driver gem required: mechanize
D, [2018-08-06 12:22:00 +0400#1686] [Child: 47180448251660] DEBUG -- amazon_crawler: Session builder: created session instance
I, [2018-08-06 12:22:00 +0400#1686] [Child: 47180448251660]  INFO -- amazon_crawler: Session: started get request to: https://www.amazon.com/Practical-Web-Scraping-Data-Science/dp/1484235819/
D, [2018-08-06 12:22:00 +0400#1686] [Child: 47180448251660] DEBUG -- amazon_crawler: Session builder: created driver instance (mechanize)
D, [2018-08-06 12:22:00 +0400#1686] [Child: 47180448251660] DEBUG -- amazon_crawler: Session: can't define driver_pid and driver_port for mechanize, not supported
I, [2018-08-06 12:22:00 +0400#1686] [Child: 47180448251660]  INFO -- amazon_crawler: Session: a new session driver has been created: driver name: mechanize, pid: , port:
I, [2018-08-06 12:22:00 +0400#1686] [Child: 47180448490460]  INFO -- amazon_crawler: Session: finished get request to: https://www.amazon.com/Web-Scraping-Python-Collecting-Modern/dp/1491985577/
I, [2018-08-06 12:22:00 +0400#1686] [Child: 47180448490460]  INFO -- amazon_crawler: Stats visits: requests: 4, responses: 2
I, [2018-08-06 12:22:01 +0400#1686] [Child: 47180448490460]  INFO -- amazon_crawler: Session: started get request to: https://www.amazon.com/Web-Scraping-Python-Collecting-Modern/dp/1491910291/
I, [2018-08-06 12:22:01 +0400#1686] [Child: 47180448535660]  INFO -- amazon_crawler: Session: finished get request to: https://www.amazon.com/Python-Web-Scraping-Cookbook-scraping/dp/1787285219/
I, [2018-08-06 12:22:01 +0400#1686] [Child: 47180448535660]  INFO -- amazon_crawler: Stats visits: requests: 5, responses: 3
I, [2018-08-06 12:22:01 +0400#1686] [Child: 47180448535660]  INFO -- amazon_crawler: Session: started get request to: https://www.amazon.com/Scraping-Python-Community-Experience-Distilled/dp/1782164367/
I, [2018-08-06 12:22:02 +0400#1686] [Child: 47180448490460]  INFO -- amazon_crawler: Session: finished get request to: https://www.amazon.com/Web-Scraping-Python-Collecting-Modern/dp/1491910291/

...

I, [2018-08-06 12:22:29 +0400#1686] [Main: 47180432147960]  INFO -- amazon_crawler: Crawler: in_parallel: stopped processing 53 urls within 3 threads, total time: 30s
I, [2018-08-06 12:22:29 +0400#1686] [Main: 47180432147960]  INFO -- amazon_crawler: Crawler: stopped: {:crawler_name=>"amazon_crawler", :status=>:completed, :environment=>"development", :start_time=>2018-08-06 12:21:48 +0400, :stop_time=>2018-08-06 12:22:29 +0400, :running_time=>"40s", :session_id=>nil, :visits=>{:requests=>54, :responses=>54, :requests_errors=>{}}, :error=>nil, :server=>{:hostname=>"my-pc", :ipv4=>"192.168.0.2", :process_pid=>1686}}

books.json

[
  {
    "title": "Web Scraping with Python: Collecting More Data from the Modern Web2nd Edition",
    "url": "https://www.amazon.com/Web-Scraping-Python-Collecting-Modern/dp/1491985577/",
    "price": "$26.94",
    "publisher": "O'Reilly Media; 2 edition (April 14, 2018)",
    "position": 1
  },
  {
    "title": "Python Web Scraping Cookbook: Over 90 proven recipes to get you scraping with Python, micro services, Docker and AWS",
    "url": "https://www.amazon.com/Python-Web-Scraping-Cookbook-scraping/dp/1787285219/",
    "price": "$39.99",
    "publisher": "Packt Publishing - ebooks Account (February 9, 2018)",
    "position": 2
  },
  {
    "title": "Web Scraping with Python: Collecting Data from the Modern Web1st Edition",
    "url": "https://www.amazon.com/Web-Scraping-Python-Collecting-Modern/dp/1491910291/",
    "price": "$15.75",
    "publisher": "O'Reilly Media; 1 edition (July 24, 2015)",
    "position": 3
  },

  ...

  {
    "title": "Instant Web Scraping with Java by Ryan Mitchell (2013-08-26)",
    "url": "https://www.amazon.com/Instant-Scraping-Java-Mitchell-2013-08-26/dp/B01FEM76X2/",
    "price": "$35.82",
    "publisher": "Packt Publishing (2013-08-26) (1896)",
    "position": 53
  }
]

Note that save_to and unique? helpers are thread-safe (protected by Mutex) and can be freely used inside threads.

in_parallel can take additional options:

• data: pass with urls custom data hash: in_parallel(:method, 3, urls: urls, data: { category: "Scraping" })
• delay: set delay between requests: in_parallel(:method, 3, urls: urls, delay: 2). Delay can be Integer, Float or Range (2..5). In case of a range, delay number will be chosen randomly for each request: rand (2..5) # => 3
• driver: set custom driver than a default one: in_parallel(:method, 3, urls: urls, driver: :poltergeist_phantomjs)
• config: pass custom options to config (see config section)

Active Support included

You can use all the power of familiar Rails core-ext methods for scraping inside Kimurai. Especially take a look at squish, truncate_words, titleize, remove, present? and presence.

Schedule crawlers using Cron

1. Inside crawler directory generate Whenever config: $ kimurai generate schedule.

schedule.rb

### Settings ###
require 'tzinfo'

# Export current PATH to the cron
env :PATH, ENV["PATH"]

# Use 24 hour format when using `at:` option
set :chronic_options, hours24: true

# Use local_to_utc helper to setup execution time using your local timezone instead
# of server's timezone (which is probably and should be UTC, to check run `$ timedatectl`).
# Also maybe you'll want to set same timezone in kimurai as well (`Kimurai.configuration.time_zone =`)
# to have crawlers logs in specific time zone format
# Example usage of helper:
# every 1.day, at: local_to_utc("7:00", zone: "Europe/Moscow") do
#   start "google_crawler.com", output: "log/google_crawler.com.log"
# end
def local_to_utc(time_string, zone:)
  TZInfo::Timezone.get(zone).local_to_utc(Time.parse(time))
end

# Note: by default Whenever exports cron commands with :environment == "production".
# Note: Whenever can only append log data to a log file (>>). If you want
# to overwrite (>) log file before each run, pass lambda:
# start "google_crawler.com", output: -> { "> log/google_crawler.com.log 2>&1" }

# project job types
job_type :start,  "cd :path && KIMURAI_ENV=:environment bundle exec kimurai start :task :output"
job_type :runner, "cd :path && KIMURAI_ENV=:environment bundle exec kimurai runner --jobs :task :output"

# single file job type
job_type :single, "cd :path && KIMURAI_ENV=:environment ruby :task :output"
# single with bundle exec
job_type :single_bundle, "cd :path && KIMURAI_ENV=:environment bundle exec ruby :task :output"

### Schedule ###
# Usage (check examples here https://github.com/javan/whenever#example-schedulerb-file):
# every 1.day do
  # Example to schedule single crawler in the project:
  # start "google_crawler.com", output: "log/google_crawler.com.log"

  # Example to schedule all crawlers in the project using runner. Each crawler will write
  # it's own output to the `log/crawler_name.log` file (handled by runner itself).
  # Runner output will be written to log/runner.log file.
  # Argument number it's a count of concurrent jobs:
  # runner 3, output:"log/runner.log"

  # Example to schedule single crawler file (without project)
  # single "single_crawler.rb", output: "single_crawler.log"
# end

### How to set cron schedule ###
# Run: `$ whenever --update-crontab --load-file config/schedule.rb`.
# If you don't have whenever command, install gem: `$ gem install whenever`.

### How to cancel schedule ###
# Run: `$ whenever --clear-crontab --load-file config/schedule.rb`.

2. Add at the bottom of file schedule.rb following code:

every 1.day, at: "7:00" do
  single "example_crawler.rb", output: "example_crawler.log"
end

3. Run: $ whenever --update-crontab --load-file schedule.rb. Done!

You can check Whenever examples here. To cancel schedule, run: $ whenever --clear-crontab --load-file schedule.rb.

Configuration options

You can configure several options using configure block:

Kimurai.configure do |config|
  # Don't colorize default logger in development mode:
  # config.colorize_logger = false

  # Logger level for default logger:
  # config.log_level = :info

  # custom logger (you can use logstash for example with multiple sources):
  # config.logger = Logger.new(STDOUT)

  # Define custom time zone for logs:
  # config.time_zone = "UTC"
  # config.time_zone = "Europe/Moscow"

  # Add custom request errors to retry:
  # config.retry_request_errors += [Net::HTTPBadGateway]
end

Automated sever setup and deployment

EXPERIMENTAL

Setup

You can automatically setup required environment for Kimurai on the remote server (currently there is only Ubuntu Server 18.04 support) using $ kimurai setup command. setup will perform installation of: latest Ruby with Rbenv, browsers with webdrivers and in additional databases clients (only clients) for MySQL, Postgres and MongoDB (so you can connect to a remote database from ruby).

To perform remote server setup, Ansible is required on the desktop machine (to install: Ubuntu: $ sudo apt install ansible, Mac OS X: $ brew install ansible)

Example:

$ kimurai setup deploy@123.123.123.123 --ask-sudo --ssh-key-path path/to/private_key

CLI options:

• --ask-sudo pass this option to ask sudo (user) password for system-wide installation of packages (apt install)
• --ssh-key-path path/to/private_key authorization on the server using private ssh key. You can omit it if required key already added to keychain on your desktop (Ansible uses SSH agent forwarding)
• --ask-auth-pass authorization on the server using user password, alternative option to --ssh-key-path.
• -p port_number custom port for ssh connection (-p 2222)

You can check setup playbook here

Deploy

After successful setup you can deploy a crawler to the server using $ kimurai deploy command. On each deploy there are performing several tasks: 1) pull repo from remote origin to ~/repo_name user directory 2) run bundle install 3) Update crontab whenever --update-crontab (to update crawler schedule from schedule.rb file).

Before deploy make sure that inside crawler directory you have: 1) git repository with remote origin (bitbucket, github, etc.) 2) Gemfile 3) schedule.rb inside subfolder config (config/schedule.rb).

Example:

$ kimurai deploy deploy@123.123.123.123 --ssh-key-path path/to/private_key --repo-key-path path/to/repo_private_key

CLI options: same like for setup command (except --ask-sudo), plus

• --repo-url provide custom repo url (--repo-url git@bitbucket.org:username/repo_name.git), otherwise current origin/master will be taken (output from $ git remote get-url origin)
• --repo-key-path if git repository is private, authorization is required to pull the code on the remote server. Use this option to provide a private repository SSH key. You can omit it if required key already added to keychain on your desktop (same like with --ssh-key-path option)

You can check deploy playbook here

Crawler @config

Using @config you can set several options for crawler, like proxy, user-agent, default cookies/headers, delay between requests, browser memory control and so on:

class Crawler < Kimurai::Base
  USER_AGENTS = ["Chrome", "Firefox", "Safari", "Opera"]
  PROXIES = ["http:2.3.4.5:8080:username:password", "http:3.4.5.6:3128", "socks5:1.2.3.4:3000"]

  @driver = :poltergeist_phantomjs
  @start_urls = ["https://example.com/"]
  @config = {
    headers: { "custom_header" => "custom_value" },
    cookies: [{ name: "cookie_name", value: "cookie_value", domain: ".example.com" }],
    user_agent: -> { USER_AGENTS.sample },
    proxy: -> { PROXIES.sample },
    window_size: [1366, 768],
    disable_images: true,
    session: {
      recreate_driver_if: {
        # Restart browser if provided memory limit (in kilobytes) is exceeded:
        memory_size: 350_000
      },
      before_request: {
        # Change user agent before each request:
        change_user_agent: true,
        # Change proxy before each request:
        change_proxy: true,
        clear_and_set_cookies: true,
        delay: 1..3
      }
    }
  }

  def parse(response, url:, data: {})
    # ...
  end
end

All available @config options

@config = {
  # Custom headers, format: hash. Example: { "some header" => "some value", "another header" => "another value" }
  # Works only for :mechanize and :poltergeist_phantomjs drivers (Selenium don't allow to set/get headers)
  headers: {},

  # Custom user agent, format: string or lambda.
  # Use lambda if you want to rotate user agents before each run:
  # user_agent: -> { ARRAY_OF_USER_AGENTS.sample }
  # Works for all drivers
  user_agent: "Mozilla/5.0 Firefox/61.0",

  # Custom cookies, format: array of hashes.
  # Format for a single cookie: { name: "cookie name", value: "cookie value", domain: ".example.com" }
  # Works for all drivers
  cookies: [],

  # Selenium drivers only: start url to visit to set custom cookies. Selenium doesn't
  # allow to set custom cookies if current browser url is empty (start page).
  # To set cookies browser needs to visit some webpage first (and domain of this
  # webpage should be the same as the domain of cookie).
  selenium_url_to_set_cookies: "http://example.com/",

  # Proxy, format: string or lambda. Format of proxy string: "protocol:ip:port:user:password"
  # `protocol` can be http or socks5. User and password are optional.
  # Use lambda if you want to rotate proxies before each run:
  # proxy: -> { ARRAY_OF_PROXIES.sample }
  # Works for all drivers, but keep in mind that Selenium drivers doesn't support proxies
  # with authorization. Also, Mechanize driver doesn't support socks5 proxy format (only http)
  proxy: "http:3.4.5.6:3128:user:pass",

  # If enabled, browser will ignore any https errors. It's handy while using a proxy
  # with self-signed SSL cert (for example Crawlera or Mitmproxy)
  # Also, it will allow to visit webpages with expires SSL certificate.
  # Works for all drivers
  ignore_ssl_errors: true,

  # Custom window size, works for all drivers
  window_size: [1366, 768],

  # Skip images downloading if true, works for all drivers
  disable_images: true,

  # Selenium drivers only: headless mode, `:native` or `:virtual_display` (default is :native)
  # Although native mode has a better performance, virtual display mode
  # sometimes can be useful. For example, some websites can detect (and block)
  # headless chrome, so you can use virtual_display mode instead
  headless_mode: :native,

  # This option tells the browser not to use a proxy for the provided list of domains or IP addresses.
  # Format: array of strings. Works only for :selenium_firefox and selenium_chrome
  proxy_bypass_list: [],

  # Option to provide custom SSL certificate. Works only for :poltergeist_phantomjs and :mechanize
  ssl_cert_path: "path/to/ssl_cert",

  # Session (browser) options
  session: {
    recreate_driver_if: {
      # Restart browser if provided memory limit (in kilobytes) is exceeded (works for all drivers)
      memory_size: 350_000,

      # Restart browser if provided requests count is exceeded (works for all drivers)
      requests_count: 100
    },
    before_request: {
      # Change proxy before each request. The `proxy:` option above should be presented
      # and has lambda format. Works only for poltergeist and mechanize drivers
      # (selenium doesn't support proxy rotation).
      change_proxy: true,

      # Change user agent before each request. The `user_agent:` option above should be presented
      # and has lambda format. Works only for poltergeist and mechanize drivers
      # (selenium doesn't support to get/set headers).
      change_user_agent: true,

      # Clear all cookies before each request, works for all drivers
      clear_cookies: true,

      # If you want to clear all cookies + set custom cookies (`cookies:` option above should be presented)
      # use this option instead (works for all drivers)
      clear_and_set_cookies: true,

      # Global option to set delay between requests.
      # Delay can be `Integer`, `Float` or `Range` (`2..5`). In case of a range,
      # delay number will be chosen randomly for each request: `rand (2..5) # => 3`
      delay: 1..3,
    }
  }
}

As you can see, most of the options are universal for any driver.

@config settings inheritance

Settings can be inherited:

class ApplicationCrawler < Kimurai::Base
  @driver = :poltergeist_phantomjs
  @config = {
    user_agent: "Firefox",
    disable_images: true,
    session: {
      recreate_driver_if: { memory_size: 350_000 },
      before_request: { delay: 1..2 }
    }
  }
end

class CustomCrawler < ApplicationCrawler
  @name = "custom_crawler"
  @start_urls = ["https://example.com/"]
  @config = {
    session: { before_request: { delay: 4..6 }}
  }

  def parse(response, url:, data: {})
    # ...
  end
end

Here, @config of CustomCrawler will be deep merged with ApplicationCrawler config, so CustomCrawler will keep all inherited options with only delay updated.

Project mode

Kimurai can work in project mode (Like Scrapy). To generate a new project, run: $ kimurai new web_crawlers (where web_crawlers is name of project).

Structure of the project:

.
├── config/
│   ├── initializers/
│   ├── application.rb
│   ├── automation.yml
│   ├── boot.rb
│   └── schedule.rb
├── crawlers/
│   └── application_crawler.rb
├── db/
├── helpers/
│   └── application_helper.rb
├── lib/
├── log/
├── pipelines/
│   ├── validator.rb
│   └── saver.rb
├── tmp/
├── .env
├── Gemfile
├── Gemfile.lock
└── README.md

Description

• config/ folder for configutation files
  • config/initializers Rails-like initializers to load custom code at start of framework
  • config/application.rb configuration settings for Kimurai (Kimurai.configure do block)
  • config/automation.yml specify some settings for setup and deploy
  • config/boot.rb loads framework and project
  • config/schedule.rb Cron schedule for crawlers
• crawlers/ folder for crawlers
  • crawlers/application_crawler.rb Base parent class for crawlers
• db/ store here all database files (sqlite, json, csv, etc.)
• helpers/ Rails-like helpers for crawlers
  • helpers/application_helper.rb all methods inside ApplicationHelper module will be available for all crawlers
• lib/ put here custom Ruby code
• log/ folder for logs
• pipelines/ folder for Scrapy-like pipelines. One file = one pipeline
  • pipelines/validator.rb example pipeline to validate item
  • pipelines/saver.rb example pipeline to save item
• tmp/ folder for temp. files
• .env file to store env variables for project and load them using Dotenv
• Gemfile dependency file
• Readme.md example project readme

Generate new crawler

To generate a new crawler in the project run:

$ kimurai generate crawler example_crawler
      create  crawlers/example_crawler.rb

Command will generate a new crawler class inherited from ApplicationCrawler:

class ExampleCrawler < ApplicationCrawler
  @name = "example_crawler"
  @start_urls = []
  @config = {}

  def parse(response, url:, data: {})
  end
end

Start

To run a particular crawler in the project, run: $ bundle exec kimurai start example_crawler. Don't forget to add bundle exec before command to load required environment.

List

To list all project crawlers, run: $ bundle exec kimurai list

Parse

For project crawlers you can use $ kimurai parse command which helps to debug crawlers:

$ bundle exec kimurai parse example_crawler parse_product --url https://example-shop.com/product-1

where example_crawler is crawler to start, parse_product is crawler method to process and --url is url to open inside processing method.

Pipelines, send_item method

You can use item pipelines to organize and store in one place item processing logic for all project crawlers (also check Scrapy description of pipelines).

Imagine if you have three crawlers where each of them crawls different e-commerce shop and saves only shoe positions. For each crawler, you want to save items only with "shoe" category, unique stock number, valid title/price and with existing images. To avoid code duplication between crawlers, use pipelines:

Show example

pipelines/validator.rb

class Validator < Kimurai::Pipeline
  def process_item(item, options: {})
    # Here you can validate item and raise `DropItemError`
    # if one of the validations failed. Examples:

    # drop item if it's category is not "shoe"
    unless item[:category] == "shoe"
      raise DropItemError, "Category is wrong"
    end

    # Check item stock number for uniqueness using buit-in unique? helper:
    unless unique?(stock_number: item[:stock_number])
      raise DropItemError, "Item is not unique"
    end

    # Drop item if title length shorter than 5 symbols:
    if item[:title].size < 5
      raise DropItemError, "Item title is too short"
    end

    # Drop item if price is nil
    unless item[:price]
      raise DropItemError, "Price is not present"
    end

    # Drop item if it doesn't contains any images:
    unless item[:images].present?
      raise DropItemError, "Images are not present"
    end

    # Pass item to the next pipeline (if it wasn't dropped):
    item
  end
end

pipelines/saver.rb

class Saver < Kimurai::Pipeline
  def process_item(item, options: {})
    # Here you can save item to the database, send it to a remote API or
    # simply save item to a file format using `save_to` helper:

    # to get the name of current crawler: `self.class.crawler.name`
    save_to "db/#{self.class.crawler.name}.json", format: :json

    item
  end
end

crawlers/application_crawler.rb

class ApplicationCrawler < Kimurai::Base
  @driver = :selenium_chrome
  # Define pipelines (by order) for all crawlers:
  @pipelines = [:validator, :saver]
end

crawlers/shop_crawler_1.rb

class ShopCrawlerOne < ApplicationCrawler
  @name = "shop_crawler_1"
  @start_urls = ["https://shop-1.com"]

  # ...

  def parse_product(response, url:, data: {})
    item = {}

    item[:title] = response.xpath("//path/to/title").text.squish
    item[:category] = response.xpath("//path/to/category").text.squish.downcase
    item[:stock_number] = response.xpath("//path/to/stock_number").text.squish.downcase
    item[:price] = response.xpath("//path/to/price").text.squish[/\d+/]&.to_i
    item[:images] = response.xpath("//path/to/images").map { |image| image[:src] }

    # Send item to pipelines:
    send_item item
  end
end

 

crawlers/shop_crawler_2.rb

class ShopCrawlerTwo < ApplicationCrawler
  @name = "shop_crawler_2"
  @start_urls = ["https://shop-2.com"]

  # ...

  def parse_product(response, url:, data: {})
    item = {}

    item[:title] = response.xpath("//path/to/title").text.squish
    item[:category] = response.xpath("//path/to/category").text.squish.downcase
    item[:stock_number] = response.xpath("//path/to/stock_number").text.squish.downcase
    item[:price] = response.xpath("//path/to/price").text.squish[/\d+/]&.to_i
    item[:images] = response.xpath("//path/to/images").map { |image| image[:src] }

    # Send item to pipelines:
    send_item item
  end
end

crawlers/shop_crawler_3.rb

class ShopCrawlerThree < ApplicationCrawler
  @name = "shop_crawler_3"
  @start_urls = ["https://shop-3.com"]

  # ...

  def parse_product(response, url:, data: {})
    item = {}

    item[:title] = response.xpath("//path/to/title").text.squish
    item[:category] = response.xpath("//path/to/category").text.squish.downcase
    item[:stock_number] = response.xpath("//path/to/stock_number").text.squish.downcase
    item[:price] = response.xpath("//path/to/price").text.squish[/\d+/]&.to_i
    item[:images] = response.xpath("//path/to/images").map { |image| image[:src] }

    # Send item to pipelines:
    send_item item
  end
end

When you start using pipelines, there are additional stats for items appears: item counts (send/processed) + dropped items errors:

Show example

pipelines/validator.rb

class Validator < Kimurai::Pipeline
  def process_item(item, options: {})
    if item[:star_count] < 10
      raise DropItemError, "Repository doesn't have enough stars"
    end

    item
  end
end

crawlers/github_crawler.rb

class GithubCrawler < ApplicationCrawler
  @name = "github_crawler"
  @driver = :mechanize
  @pipelines = [:validator]
  @start_urls = ["https://github.com/search?q=Ruby%20Web%20Scraping"]
  @config = {
    user_agent: "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.84 Safari/537.36"
  }

  def parse(response, url:, data: {})
    response.xpath("//ul[@class='repo-list']/div//h3/a").each do |a|
      request_to :parse_repo_page, url: absolute_url(a[:href], base: url)
    end

    if next_page = response.at_xpath("//a[@class='next_page']")
      request_to :parse, url: absolute_url(next_page[:href], base: url)
    end
  end

  def parse_repo_page(response, url:, data: {})
    item = {}

    item[:owner] = response.xpath("//h1//a[@rel='author']").text
    item[:repo_name] = response.xpath("//h1/strong[@itemprop='name']/a").text
    item[:repo_url] = url
    item[:description] = response.xpath("//span[@itemprop='about']").text.squish
    item[:tags] = response.xpath("//div[@id='topics-list-container']/div/a").map { |a| a.text.squish }
    item[:watch_count] = response.xpath("//ul[@class='pagehead-actions']/li[contains(., 'Watch')]/a[2]").text.squish.delete(",").to_i
    item[:star_count] = response.xpath("//ul[@class='pagehead-actions']/li[contains(., 'Star')]/a[2]").text.squish.delete(",").to_i
    item[:fork_count] = response.xpath("//ul[@class='pagehead-actions']/li[contains(., 'Fork')]/a[2]").text.squish.delete(",").to_i
    item[:last_commit] = response.xpath("//span[@itemprop='dateModified']/*").text

    send_item item
  end
end

$ bundle exec kimurai start github_crawler

D, [2018-08-08 14:49:17 +0400#20515] [Main: 47341785277920] DEBUG -- github_crawler: Session builder: driver gem required: mechanize
D, [2018-08-08 14:49:17 +0400#20515] [Main: 47341785277920] DEBUG -- github_crawler: Session builder: created session instance
D, [2018-08-08 14:49:17 +0400#20515] [Main: 47341785277920] DEBUG -- github_crawler: Session builder: created driver instance (mechanize)
D, [2018-08-08 14:49:17 +0400#20515] [Main: 47341785277920] DEBUG -- github_crawler: Session: can't define driver_pid and driver_port for mechanize, not supported
I, [2018-08-08 14:49:17 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: a new session driver has been created: driver name: mechanize, pid: , port:
D, [2018-08-08 14:49:17 +0400#20515] [Main: 47341785277920] DEBUG -- github_crawler: Session builder: enabled custom useragent for mechanize
I, [2018-08-08 14:49:17 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: started get request to: https://github.com/search?q=Ruby%20Web%20Scraping
I, [2018-08-08 14:49:19 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: finished get request to: https://github.com/search?q=Ruby%20Web%20Scraping
I, [2018-08-08 14:49:19 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Stats visits: requests: 1, responses: 1
I, [2018-08-08 14:49:19 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: started get request to: https://github.com/lorien/awesome-web-scraping
I, [2018-08-08 14:49:19 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: finished get request to: https://github.com/lorien/awesome-web-scraping
I, [2018-08-08 14:49:19 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Stats visits: requests: 2, responses: 2
D, [2018-08-08 14:49:19 +0400#20515] [Main: 47341785277920] DEBUG -- github_crawler: Pipeline: starting processing item through 1 pipeline...
I, [2018-08-08 14:49:19 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Pipeline: processed item: {"owner":"lorien","repo_name":"awesome-web-scraping","repo_url":"https://github.com/lorien/awesome-web-scraping","description":"List of libraries, tools and APIs for web scraping and data processing.","tags":["awesome","awesome-list","web-scraping","data-processing","python","javascript","php","ruby"],"watch_count":161,"star_count":2403,"fork_count":349,"last_commit":"Jul 16, 2018"}
I, [2018-08-08 14:49:19 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Stats items: sent: 1, processed: 1
I, [2018-08-08 14:49:19 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: started get request to: https://github.com/jaimeiniesta/metainspector
I, [2018-08-08 14:49:20 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: finished get request to: https://github.com/jaimeiniesta/metainspector
I, [2018-08-08 14:49:20 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Stats visits: requests: 3, responses: 3
D, [2018-08-08 14:49:20 +0400#20515] [Main: 47341785277920] DEBUG -- github_crawler: Pipeline: starting processing item through 1 pipeline...
I, [2018-08-08 14:49:20 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Pipeline: processed item: {"owner":"jaimeiniesta","repo_name":"metainspector","repo_url":"https://github.com/jaimeiniesta/metainspector","description":"Ruby gem for web scraping purposes. It scrapes a given URL, and returns you its title, meta description, meta keywords, links, images...","tags":[],"watch_count":21,"star_count":805,"fork_count":137,"last_commit":"May 15, 2018"}
I, [2018-08-08 14:49:20 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Stats items: sent: 2, processed: 2

...

I, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: started get request to: https://github.com/yomete/scrapertutorial
I, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: finished get request to: https://github.com/yomete/scrapertutorial
I, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Stats visits: requests: 13, responses: 13
D, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920] DEBUG -- github_crawler: Pipeline: starting processing item through 1 pipeline...
E, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920] ERROR -- github_crawler: Pipeline: dropped item: #<Kimurai::Pipeline::DropItemError: Repository doesn't have enough stars>: {:owner=>"yomete", :repo_name=>"scrapertutorial", :repo_url=>"https://github.com/yomete/scrapertutorial", :description=>"Code Repository for a tutorial on web scraping with Rails", :tags=>["rails", "ruby", "nokogiri", "scraping-websites"], :watch_count=>1, :star_count=>4, :fork_count=>2, :last_commit=>"Feb 25, 2017"}
E, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920] ERROR -- github_crawler: Pipeline: full error: Traceback (most recent call last):
...
/home/victor/code/web_crawlers/pipelines/validator.rb:4:in `process_item': Repository doesn't have enough stars (Kimurai::Pipeline::DropItemError)

I, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Stats items: sent: 11, processed: 10
I, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: started get request to: https://github.com/jonstokes/stretched.io
I, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: finished get request to: https://github.com/jonstokes/stretched.io
I, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Stats visits: requests: 14, responses: 14
D, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920] DEBUG -- github_crawler: Pipeline: starting processing item through 1 pipeline...
E, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920] ERROR -- github_crawler: Pipeline: dropped item: #<Kimurai::Pipeline::DropItemError: Repository doesn't have enough stars>: {:owner=>"jonstokes", :repo_name=>"stretched.io", :repo_url=>"https://github.com/jonstokes/stretched.io", :description=>"a JSON/Ruby web scraping PaaS", :tags=>[], :watch_count=>1, :star_count=>8, :fork_count=>0, :last_commit=>"Aug 27, 2015"}
E, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920] ERROR -- github_crawler: Pipeline: full error: Traceback (most recent call last):
...
/home/victor/code/web_crawlers/pipelines/validator.rb:4:in `process_item': Repository doesn't have enough stars (Kimurai::Pipeline::DropItemError)

I, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Stats items: sent: 12, processed: 10
I, [2018-08-08 14:49:24 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Session: started get request to: https://github.com/albertobraschi/ronin-web

...

I, [2018-08-08 14:50:42 +0400#20515] [Main: 47341785277920]  INFO -- github_crawler: Crawler: stopped: {:crawler_name=>"github_crawler", :status=>:completed, :environment=>"development", :start_time=>2018-08-08 14:49:17 +0400, :stop_time=>2018-08-08 14:50:42 +0400, :running_time=>"1m, 24s", :session_id=>nil, :visits=>{:requests=>138, :responses=>138, :requests_errors=>{}, :items=>{:sent=>125, :processed=>11, :drop_errors=>{"#<Kimurai::Pipeline::DropItemError: Repository doesn't have enough stars>"=>114}}, :error=>nil, :server=>{:hostname=>"my-pc", :ipv4=>"192.168.0.2", :process_pid=>20515}}

Also, you can pass custom options to pipeline from a particular crawler if you want to change pipeline behavior for this crawler:

Show example

crawlers/custom_crawler.rb

class CustomCrawler < ApplicationCrawler
  @name = "custom_crawler"
  @start_urls = ["https://example.com"]
  @pipelines = [:validator]

  # ...

  def parse_item(response, url:, data: {})
    item = {}

    # ...

    # Pass custom option `skip_uniq_checking` for Validator pipeline:
    send_item item, validator: { skip_uniq_checking: true }
  end
end

pipelines/validator.rb

class Validator < Kimurai::Pipeline
  def process_item(item, options: {})

    # Do not check item stock number for uniqueness if options[:skip_uniq_checking] == true
    unless options[:skip_uniq_checking] == true
      raise DropItemError, "Item is not unique" unless unique?(stock_number: item[:stock_number])
    end
  end
end

Runner

EXPERIMENTAL

You can run project crawlers one by one or in parallel using $ kimurai runner command:

$ bundle exec kimurai list
custom_crawler
example_crawler
github_crawler

$ bundle exec kimurai runner -j 3
>> Runner: started session: {:id=>1533727423, :status=>:processing, :start_time=>2018-08-08 15:23:43 +0400, :stop_time=>nil, :environment=>"development", :concurrent_jobs=>3, :crawlers=>["custom_crawler", "github_crawler", "example_crawler"]}
> Runner: started crawler: custom_crawler, index: 0
> Runner: started crawler: github_crawler, index: 1
> Runner: started crawler: example_crawler, index: 2
< Runner: stopped crawler: custom_crawler, index: 0
< Runner: stopped crawler: example_crawler, index: 2
< Runner: stopped crawler: github_crawler, index: 1
>> Runner: stopped session: {:id=>1533727423, :status=>:completed, :start_time=>2018-08-08 15:23:43 +0400, :stop_time=>2018-08-08 15:25:11 +0400, :environment=>"development", :concurrent_jobs=>3, :crawlers=>["custom_crawler", "github_crawler", "example_crawler"]}

Each crawler runs in separate process. Crawlers logs available at log/ folder. Pass -j option to specify how many crawlers should be processed at the same time (default is 1).

Runner (session) callbacks

You can perform custom actions before runner starts and after runner stops using config.runner_at_start_callback and config.runner_at_stop_callback. Check config/application.rb to see example.

Stats database + dashboard

EXPERIMENTAL

Kimurai can save info about crawlers runs and runner sessions to a database (project mode only). To enable this feature you need to set config.stats_database_url in config/application.rb. Stats can be saved to an SQlite, MySQL or Postgres database.

To check stats you can run simple Kimurai dashboard:

$ bundle exec kimurai dashboard
[2018-08-08 16:11:40] INFO  WEBrick 1.4.2
[2018-08-08 16:11:40] INFO  ruby 2.5.1 (2018-03-29) [x86_64-linux]
== Sinatra (v2.0.3) has taken the stage on 4567 for development with backup from WEBrick
[2018-08-08 16:11:40] INFO  WEBrick::HTTPServer#start: pid=12903 port=4567

# you can see dashboard at http://localhost:4567

See config/application.rb for an additional info.

Chat Support and Feedback

Join Kimurai community on Gitter

Author

Victor Afanasev - https://victorafanasev.info/

License

The gem is available as open source under the terms of the MIT License.