ソースコード

だいぶはしょってますが、クロールするための、Crawlerクラスです。

require 'selenium-webdriver'

class Crawler
  def execute
    driver.navigate.to start_url
    driver.find_elements(:xpath, '//*[@id="tabular-buybox"]/div[1]/div[4]/div/span/a')
    # 以下略
  end
    
  private

  def driver
    @driver ||= begin
      options = Selenium::WebDriver::Chrome::Options.new
      options.add_argument('--headless')
      Selenium::WebDriver.for(:chrome , options: options).tap do |driver|
        driver.manage.timeouts.implicit_wait = 2
      end
    end
  end
end

問題

Dockerコンテナ内で、上記を動かすと以下のエラーが発生

Selenium::WebDriver::Error::UnknownError
"unknown error: Chrome failed to start: exited abnormally.\n  (unknown error: DevToolsActivePort file doesn't exist)\n  (The process started from chrome location /usr/bin/google-chrome is no longer running, so ChromeDriver is assuming that Chrome has crashed.)"

解決策

--no-sandboxと、--disable-dev-shm-usageオプションを追加しましょう！

  def driver
    @driver ||= begin
      options = Selenium::WebDriver::Chrome::Options.new
      options.add_argument('--headless')
      options.add_argument('--no-sandbox') # 追加
      options.add_argument('--disable-dev-shm-usage') # 追加
      Selenium::WebDriver.for(:chrome , options: options).tap do |driver|
        driver.manage.timeouts.implicit_wait = 2
      end
    end
  end