Class: Staticizer::Crawler

Inherits:
Object
  • Object
show all
Defined in:
lib/staticizer/crawler.rb

Instance Method Summary collapse

Constructor Details

#initialize(initial_page, opts = {}) ⇒ Crawler

Returns a new instance of Crawler.



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# File 'lib/staticizer/crawler.rb', line 9

def initialize(initial_page, opts = {})
  if initial_page.nil?
    raise ArgumentError, "Initial page required"
  end

  @opts = opts.dup
  @url_queue = []
  @processed_urls = []
  @opts[:output_dir] ||= File.expand_path("crawl/")
  @log = @opts[:logger] || Logger.new(STDOUT)
  @log.level = @opts[:log_level] || Logger::INFO

  if @opts[:aws]
    bucket_name = @opts[:aws].delete(:bucket_name)
    AWS.config(opts[:aws])
    @s3_bucket = AWS::S3.new.buckets[bucket_name]
    @s3_bucket.acl = :public_read
  end

  if @opts[:valid_domains].nil?
    uri = URI.parse(initial_page)
    @opts[:valid_domains] ||= [uri.host]
  end
  add_url(initial_page)
end

Instance Method Details

#add_url(url, info = {}) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 75

def add_url(url, info = {})
  if @opts[:filter_url]
    url = @opts[:filter_url].call(url, info)
    return if url.nil?
  else
    regex = "(#{@opts[:valid_domains].join(")|(")})"
    return if url !~ %r{^https?://#{regex}}
  end

  url = url.sub(/#.*$/,'') # strip off any fragments
  return if @url_queue.index {|u| u[0] == url } || @processed_urls.include?(url)
  @url_queue << [url, info]
end

#add_urls(urls, info = {}) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 65

def add_urls(urls, info = {})
  urls.compact.uniq.each {|url| add_url(url, info.dup) }
end

#crawl ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 35

def crawl
  @log.info("Starting crawl")
  while(@url_queue.length > 0)
    url, info = @url_queue.shift
    @processed_urls << url
    process_url(url, info)
  end
  @log.info("Finished crawl")
end

#extract_css_urls(css, base_uri) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 61

def extract_css_urls(css, base_uri)
  css.scan(/url\(([^)]+)\)/).map {|src| make_absolute(base_uri, src[0]) }
end

#extract_hrefs(doc, base_uri) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 45

def extract_hrefs(doc, base_uri)
  doc.xpath("//a/@href").map {|href| make_absolute(base_uri, href) }
end

#extract_images(doc, base_uri) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 49

def extract_images(doc, base_uri)
  doc.xpath("//img/@src").map {|src| make_absolute(base_uri, src) }
end

#extract_links(doc, base_uri) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 53

def extract_links(doc, base_uri)
  doc.xpath("//link/@href").map {|href| make_absolute(base_uri, href) }
end

#extract_scripts(doc, base_uri) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 57

def extract_scripts(doc, base_uri)
  doc.xpath("//script/@src").map {|src| make_absolute(base_uri, src) }
end

#make_absolute(base_uri, href) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 69

def make_absolute(base_uri, href)
  URI::join(base_uri, href).to_s
rescue StandardError => e
  @log.error "Could not make absolute #{base_uri} - #{href}"
end

#process_redirect(url, destination_url) ⇒ Object

If we hit a redirect we save the redirect as a meta refresh page TODO: for AWS S3 hosting we could instead create a redirect?



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# File 'lib/staticizer/crawler.rb', line 176

def process_redirect(url, destination_url)
  body = "<html><head><META http-equiv='refresh' content='0;URL=\"#{destination_url}\"'></head><body>You are being redirected to <a href='#{destination_url}'>#{destination_url}</a>.</body></html>"
  save_page_to_aws(body, url)
end

#process_success(response, parsed_uri) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 156

def process_success(response, parsed_uri)
  url = parsed_uri.to_s
  case response['content-type']
  when /css/
    save_page(response, parsed_uri)
    add_urls(extract_css_urls(response.body, url), {:type_hint => "css_url"})
  when /html/
    save_page(response, parsed_uri)
    doc = Nokogiri::HTML(response.body)
    add_urls(extract_links(doc, url), {:type_hint => "link"})
    add_urls(extract_scripts(doc, url), {:type_hint => "script"})
    add_urls(extract_images(doc, url), {:type_hint => "image"})
    add_urls(extract_hrefs(doc, url), {:type_hint => "href"})
  else
    save_page(response, parsed_uri)
  end
end

#process_url(url, info) ⇒ Object

Fetch a URI and save it to disk



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# File 'lib/staticizer/crawler.rb', line 182

def process_url(url, info)
  @http_connections ||= {}
  parsed_uri = URI(url)

  @log.debug "Fetching #{parsed_uri}"

  # Attempt to use an already open Net::HTTP connection
  key = parsed_uri.host + parsed_uri.port.to_s
  connection = @http_connections[key]
  if connection.nil?
    connection = Net::HTTP.new(parsed_uri.host, parsed_uri.port)
    @http_connections[key] = connection
  end

  request = Net::HTTP::Get.new(parsed_uri.request_uri)
  connection.request(request) do |response|
    case response
    when Net::HTTPSuccess
      process_success(response, parsed_uri)
    when Net::HTTPRedirection
      redirect_url = response['location']
      @log.debug "Processing redirect to #{redirect_url}"
      process_redirect(parsed_uri, redirect_url)
      add_url(redirect_url)
    else
      @log.error "Error #{response.code}:#{response.message} fetching url #{url}"
    end
  end
end

#save_page(response, uri) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 89

def save_page(response, uri)
  if @opts[:aws]
    save_page_to_aws(response, uri)
  else
    save_page_to_disk(response, uri)
  end
end

#save_page_to_aws(response, uri) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 140

def save_page_to_aws(response, uri)
  key = uri.path
  key += "?#{uri.query}" if uri.query
  key = key.gsub(%r{^/},"")
  key = "index.html" if key == ""
  # Upload this file directly to AWS::S3
  opts = {:acl => :public_read}
  opts[:content_type] = response['content-type'] rescue "text/html"
  @log.info "Uploading #{key} to s3 with content type #{opts[:content_type]}"
  if response.respond_to?(:read_body)
    @s3_bucket.objects[key].write(response.read_body, opts)
  else
    @s3_bucket.objects[key].write(response, opts)  
  end      
end

#save_page_to_disk(response, uri) ⇒ Object 



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# File 'lib/staticizer/crawler.rb', line 97

def save_page_to_disk(response, uri)
  path = uri.path
  path += "?#{uri.query}" if uri.query

  path_segments = path.scan(%r{[^/]*/})
  filename = path.include?("/") ? path[path.rindex("/")+1..-1] : path

  current = @opts[:output_dir]
  FileUtils.mkdir_p(current) unless File.exist?(current)

  # Create all the directories necessary for this file
  path_segments.each do |segment|
    current = File.join(current, "#{segment}").sub(%r{/$},'')
    if File.file?(current)
      # If we are trying to create a directory and there already is a file
      # with the same name add a .d to the file since we can't create
      # a directory and file with the same name in the file system
      dirfile = current + ".d"
      FileUtils.mv(current, dirfile)
      FileUtils.mkdir(current)
      FileUtils.cp(dirfile, File.join(current, "/index.html"))
    elsif !File.exists?(current)
      FileUtils.mkdir(current)
    end
  end

  body = response.respond_to?(:read_body) ? response.read_body : response
  outfile = File.join(current, "/#{filename}")
  if filename == ""
    indexfile = File.join(outfile, "/index.html")
    @log.info "Saving #{indexfile}"
    File.open(indexfile, "wb") {|f| f << body }
  elsif File.directory?(outfile)
    dirfile = outfile + ".d"
    @log.info "Saving #{dirfile}"
    File.open(dirfile, "wb") {|f| f << body }
    FileUtils.cp(dirfile, File.join(outfile, "/index.html"))
  else
    @log.info "Saving #{outfile}"
    File.open(outfile, "wb") {|f| f << body }
  end
end