Capybara、Selenium、无头 Chrome、Ubuntu Net::ReadTimeout答案

【问题标题】：Capybara, Selenium, headless Chrome, Ubuntu Net::ReadTimeoutCapybara、Selenium、无头 Chrome、Ubuntu Net::ReadTimeout
【发布时间】：2017-09-11 20:17:53
【问题描述】：

我看到了一个与我非常相似的问题。在 OS X 上一切正常，但在 ubuntu 14.04 上抛出错误。回溯那篇文章，我得到了同样的错误。最初的海报放弃了，改用 Poltergeist / PhantomJS。既然 PhantomJS 不再维护，我想在 Chrome 上进行这项工作。

Net::ReadTimeout: Net::ReadTimeout and Selenium::WebDriver::Error::UnknownError: unknown error: Chrome failed to start on Rails 5.1.beta System Test

这是我在 Ubuntu 上的安装步骤：

apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 40976EAF437D05B5
wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add - 
cat <<EOF > /etc/apt/sources.list.d/google-chrome.list
deb http://dl.google.com/linux/chrome/deb/ stable main
EOF
apt-get update
apt-get install --force-yes -y google-chrome-stable
cd /root/ && curl -O "http://chromedriver.storage.googleapis.com/2.32/chromedriver_linux64.zip"
cd /root/ && unzip chromedriver_linux64.zip && cp chromedriver /usr/bin

一步一步，我确认 google-chrome、chromedriver 安装正确并且工作正常。 Selenium 驱动程序也可以正常工作。

link = ENV['LINK'] || "https://www.amazon.com"
#https://stackoverflow.com/questions/44424200/how-do-i-use-selenium-webdriver-on-headless-chrome
Selenium::WebDriver::Chrome.driver_path="/usr/bin/chromedriver" if RUBY_PLATFORM.include? "linux"
options = %w[--headless --disable-gpu]
options +=  %w[--binary='/usr/bin/google-chrome'] if RUBY_PLATFORM.include? "linux"
driver = Selenium::WebDriver.for :chrome, switches: options
driver.navigate.to "#{link}"
driver.save_screenshot("./screen.png")
driver.quit

访问 url 时 Capybara 测试超时。

require 'capybara'
include Capybara::DSL

link = ENV['LINK'] || "https://www.amazon.com"
options = %w[--headless --disable-gpu]
options +=  %w[--binary='/usr/bin/google-chrome'] if RUBY_PLATFORM.include? "linux"
Selenium::WebDriver::Chrome.driver_path="/usr/bin/chromedriver" if RUBY_PLATFORM.include? "linux"
Capybara.register_driver(:headless_chrome) do |app|
    capabilities = Selenium::WebDriver::Remote::Capabilities.chrome( chromeOptions: { args: options } )
    Capybara::Selenium::Driver.new(app, browser: :chrome, desired_capabilities: capabilities )
end
Capybara.javascript_driver = :headless_chrome
session = Capybara::Session.new(:headless_chrome)
session.visit "#{link}"

错误是以下消息：

session.visit "#{link}"

Net::ReadTimeout: Net::ReadTimeout
    from /usr/lib/ruby/2.3.0/net/protocol.rb:158:in `rbuf_fill'
    from /usr/lib/ruby/2.3.0/net/protocol.rb:136:in `readuntil'
    from /usr/lib/ruby/2.3.0/net/protocol.rb:146:in `readline'
    from /usr/lib/ruby/2.3.0/net/http/response.rb:40:in `read_status_line'
    from /usr/lib/ruby/2.3.0/net/http/response.rb:29:in `read_new'
    from /usr/lib/ruby/2.3.0/net/http.rb:1437:in `block in transport_request'
    from /usr/lib/ruby/2.3.0/net/http.rb:1434:in `catch'
    from /usr/lib/ruby/2.3.0/net/http.rb:1434:in `transport_request'
    from /usr/lib/ruby/2.3.0/net/http.rb:1407:in `request'
    from /usr/lib/ruby/2.3.0/net/http.rb:1400:in `block in request'
    from /usr/lib/ruby/2.3.0/net/http.rb:853:in `start'
    from /usr/lib/ruby/2.3.0/net/http.rb:1398:in `request'
    from /var/www/railsapp/vendor/bundle/ruby/2.3.0/gems/selenium-webdriver-2.53.4/lib/selenium/webdriver/remote/http/default.rb:107:in `response_for'
    from /var/www/railsapp/vendor/bundle/ruby/2.3.0/gems/selenium-webdriver-2.53.4/lib/selenium/webdriver/remote/http/default.rb:58:in `request'
    from /var/www/railsapp/vendor/bundle/ruby/2.3.0/gems/selenium-webdriver-2.53.4/lib/selenium/webdriver/remote/http/common.rb:59:in `call'
    from /var/www/railsapp/vendor/bundle/ruby/2.3.0/gems/selenium-webdriver-2.53.4/lib/selenium/webdriver/remote/bridge.rb:649:in `raw_execute'
... 10 levels...
    from /usr/bin/irb:11:in `<top (required)>'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/lib/bundler/cli/exec.rb:74:in `load'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/lib/bundler/cli/exec.rb:74:in `kernel_load'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/lib/bundler/cli/exec.rb:27:in `run'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/lib/bundler/cli.rb:332:in `exec'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/lib/bundler/vendor/thor/lib/thor/invocation.rb:126:in `invoke_command'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/lib/bundler/vendor/thor/lib/thor.rb:359:in `dispatch'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/lib/bundler/cli.rb:20:in `dispatch'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/lib/bundler/vendor/thor/lib/thor/base.rb:440:in `start'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/lib/bundler/cli.rb:11:in `start'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/exe/bundle:34:in `block in <top (required)>'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/lib/bundler/friendly_errors.rb:100:in `with_friendly_errors'
    from /usr/lib/ruby/gems/2.3.0/gems/bundler-1.13.6/exe/bundle:26:in `<top (required)>'
    from /usr/bin/bundle:23:in `load'
    from /usr/bin/bundle:23:in `<main>'

【问题讨论】：

你为什么在你的 Selenium only 测试和 Capybara 的 Selenium 测试中传递不同的选项给 Selenium？除了 :browser 之外的所有选项基本上都直接传递给 Selenium - 所以要使测试等效，您需要在驱动程序注册中执行 Capybara::Selenium::Driver.new(app, browser: :chrome, switches: options)。此外，这不是您实际运行的唯一代码，因为您需要“capybara/dsl”和“selenium-webdriver”才能使该代码实际运行。
另外，你的 selenium 已经过时了（2.53.4 可能无法正常使用 headless chrome）
我将 selenium-webdriver 更新到 3.5.2 并在注册驱动程序时使用您的建议传递选项。有效！ :) 将您的 cmets 放入答案中，我会选择它。
添加为答案

标签： google-chrome selenium ubuntu capybara selenium-chromedriver

【解决方案1】：

Headless Chrome 和支持它的 chromedriver 相对较新。将您的 selenium-webdriver 更新到最新版本（截至本答案为 3.5.2）以获得对它的支持。完成后，如果您使用的是最新的 Capybara，您也可以尝试仅使用 Capybara 提供的注册驱动程序，使用

if RUBY_PLATFORM.include? "linux"
  Selenium::WebDriver::Chrome.driver_path = "/usr/bin/chromedriver"
  Selenium::WebDriver::Chrome.path = "/usr/bin/google-chrome"
end
Capybara.javascript_driver = :selenium_chrome_headless

而不是需要注册自己的驱动程序。

【讨论】：