Headless Chrome is coming soon | Hacker News Reader

Headless Chrome is coming soon

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293 pointsAnbeSivam45 comments

That would be so awesome. The current alternatives:

1. Use PhantomJS: It easy to script, but it lags over real browser by few years and development is stagnant. Many real website doesn't work in PhantomJS.

2. Use Chrome/Firefox xvfb. You have real browser, but scripting is hard. E.g. even hello world examples like make a thumbnail of a website takes a lot of time to get right.

According to some rumors, headless Chrome existed before even Chrome was released to the public. Google use it to do web scraping. However, though headless browsers are great for developers, they are also great for spammers and ad fraud. So the main developer likely has conflict of interests whether to invest resources into making headless Chrome public.

What about Selenium? Is it already covered in point 2?

Yes you can do it with Selenium (I mean that in point 2), but IMO it is hard to setup and resource consuming. E.g. You need separate VM or Docket to have browser with virtual frame buffer. Using Web Driver also got a steep learning curve.

Well, some people also ask why world ever need Ruby with Rails or Python with Django? You can write any website in Enterprise Java since late 1990s. Same Docker vs. Virtual Machines or Atom vs. Vim/Emacs. Even if capability is there, there is room for improvement. Especially if you can make it easier to use and make developers more productive by an order of magnitude.

As someone with a horrible internet connection, I've often resorted to using a VPS, Selenium + Firefox+ xvfb is definitely resourcee-intensive and a pain.

No functional need for a separate VM: xvfb-run -a will automatically pick the next free display number and set up the environment pointing to xvfb's $DISPLAY. Of course container/vm isolation is still a good idea for security and repeatability reasons.

> Using Web Driver also got a steep learning curve.

I would recommend not working with WebDriver directly. There are many projects that wrap it in a sane API and make it very easy to use. For example if you're using Javascript then use http://webdriver.io instead of directly using the Selenium WebDriver API.

> IMO it is hard to setup and resource consuming

What issues have you had? It's always been very easy to setup in my experience.

The only two 'issues' I've had are correct management of the Selenium server within a task running context and odd interactions with some browsers when they are driven by selenium (e.g. safari considering `window.open()` to always be a popup from selenium triggered actions).

I used http://nightwatchjs.org/ as a library talk to selenium, but plethora of WebDriver wrapper rather confused me, than added value.

Btw, can you point me to some tutorial that teach you in 15 minutes from zero how to setup something that can change any url into a thumbnail screen shoot. You can do that with phantomjs:

brew install phantomjs

http://phantomjs.org/screen-capture.html

Maybe a selenium pro can do it quickly, but for me:

1. How to install selenium? It took me few attempts until I realized that Docker containers are the best way.

2. Install Docker on MacOS and start container.

3. Find some toolkit that talks to selenium. There are tons of libraries, but just some have reasonable docs and are well maintained.

4. Configure this toolkit so it can talk to Selenium.

5. Beware if your container die. Also figuring out that website is loaded is also non-trivial in Selenium and default are worse than in PhantomJS.

6. Etc.

I'm kind of curious how you came to Docker and PhantomJS being the easiest way, that sounds like the worst possible way to me.

To get things started simply with JS just follow instructions here: http://webdriver.io/guide.html

The only major diversions from that are to use Mocha or Jasmine for your test framework (instructions on the same site) and to automate starting / stopping the selenium server for which there are grunt/gulp plugins.

Another good option is Scrapy combined with Splash.

Another downside to the selenium API is that there is no way to get any upstream HTTP status or network error. That includes redirects unfortunately.

I'm using a Chrome plugin for that purpose, which complicates the whole setup even further.

You could use a proxy like browsermob, which you can connect via the selenium API.

That's yet another moving part with its own error modes.

And I'm not quite sure (without having it thought through) how I would do something like get the URL of the last permanent redirect and correlate it with the original request. I'm sure it's possible somehow, but it doesn't seem exactly straightforward.

There's also Nightmare, which is built off Atom. We ported all of our PhantomJS-backed headless tests to Nightmare recently, and it's paid in dividends: http://www.nightmarejs.org

Mozilla Servo has a headless mode, but PITA to get it working.

Option 3: SlimerJS[1]. We evaluated it for testing CSP2 functionality which WebKit doesn’t yet support.

[1] http://slimerjs.org/

If this would benefit you - please star this issue: https://bugs.chromium.org/p/chromium/issues/detail?id=546953

From the bug comments:

  headless: Implement screenshot capturing
  
  (based on patch from skyostil@, also sets default window 
  size to 800x600 to enable basic snapshot support)
  
  With the --screenshot option, headless shell will save a 
  PNG screenshot of the loaded page.

Just out of curiosity - when does Chrome consider a page "loaded"? Is it the classic window.onload or something fancier?

Not an answer to your question, but somewhat related:

I recently worked on an automated thumbnail generator which used PhantomJS (headless Webkit browser) to load some 20000 pages and screenshot them. The problem was that these pages had javascript code that would start loading resources long after `onload` and friends had fired. So the way I implemented onload was to monitor all resources and if there was delay of few seconds after the last one had finished, I'd consider the page loaded. It turned out to be quite robust.

There are a few events that get fired during a page load. DOMCotentLoaded is fired when the page and all its assets are loaded, so that's usually considered the point at which it's finished loading. With modern JS based pages that sometimes isn't enough though, so new browsers have documentRequestIdleCallback which fires a callback when the browser isn't busy, which is quite useful.

Are you not confusing DOMContentLoaded with window.load? DCL doesn't wait for assets last time I checked, it only waits until the page is parsed and a tree has been created. .load waits for assets https://developer.mozilla.org/en-US/docs/Web/Events/DOMConte...

To add to what oxplot and onion2k said, with both PhantomJS and Electron (when using xvfb) I have found that waiting for the DOMCotentLoaded or with PhantomJS the onLoadFinished event (I think this is similar to documentRequestIdleCallback) usually works.

However sometimes the page still hasn't finished drawing and so I do a couple of requestAnimationFrame's after the DOMCotentLoaded to ensure that everything is drawn to the screen buffer.

I just use XVFB.

  xvfb-run --server-args='-screen 0 1024x768x24 -ac' chromium-browser --user-data-dir <url>

I do to, but not for testing (we don't actually do any scripted UI tests, we should, but they are time consuming to write). We have a Python service that uses Firefox, Selenium and XVFB (through the awesome PyVirtualDisplay library, check it out) to log into a website that uses an annoying Java applet + scripting for authentication. This ended up cutting off a huge headache where previously we were doing this in a Windows scheduled task that needed an active console session to do anything.

Could this be used for Selenium tests too? And with visual diff testing tools?

I don't see why not. You can do it today with headless options like PhantomJS (headless WebKit), and this seems to be intended for similar uses.

You can also do it with my project which is based only on Java, https://github.com/machinepublishers/jbrowserdriver

I haven't started using it but it looks like a great project (learned about it from ghostdriver homepage). There is a dearth of actively maintained projects that is compatible with selenium. While headless is not a requirement for us, having the node start and connect to selenium hub instead of selenium hub starting it on demand was extremely important. Phantomjs was the only other project which did that but it has not been very stable. Thank you for your work on this :)

The required work for Selenium compatibility is tracked here: https://bugs.chromium.org/p/chromium/issues/detail?id=604324 (And yes, it is a blocking issue).

This is great news. In general I'm hoping this makes it easier to do browser testing in more CI services, rather than isolating this type of testing to services that have to specialize in it just to get it to to work.

One (minor?) benefit over Phantom is having working file uploads, though it would be awesome to have that in Phantom too.

We upload files in our integration tests using PhantomJS. At least, I'm pretty sure we do (we use Capybara to drive PhantomJS). Am I missing something?

Another way to solve this problem is to have Chrome in a docker container that you can start up: https://github.com/SeleniumHQ/docker-selenium

I use the Chrome and Firefox docker-selenium containers in Testcontainers [1][2], my project for running containers to support JUnit tests.

I created this after numerous issues with PhantomJS compatibility and debuggability; Testcontainers instead uses the real browsers, and also offers automatic video recording of test sessions and VNC access for debugging.

Headless chrome support sounds like a good step forward, but if visibility into what's going on is limited then I feel there's going to be some way to go. Perhaps chrome remote debugging support?

[1]: http://testcontainers.viewdocs.io/testcontainers-java/ [2]: https://rnorth.org/26/better-junit-selenium-testing-with-doc...

Just because it is headless doesn't mean it can't render to a serializable format (like a pdf)

Thanks for noticing, I upgraded the "Alternatives" section at https://github.com/elgalu/docker-selenium#alternatives

This is awesome. I've been using Electron for browser tests which has been a big improvement over Phantom, but setting up xvfb can be a pain.

Please link the source and not twitter next time.

Great news! I hope this will allow to change the hard-coded limit of the maximum number of connection per server in Chrome [1].

[1] https://bugs.chromium.org/p/chromium/issues/detail?id=85323

Isn't chromium already bundled with chromedriver? Or at least it is on arch linux. (fyi, chromedriver conflicts chromium in aur because of this)

I believe the difference is that chromedriver still spins up all the normal chrome interface, which wouldn't be needed for the headless chrome. I think the stated deliverables help discern the intention:

1. A library which headless applications can link to to. 2. A sample application which demonstrates the use of headless APIs.

I wanted this 10 years ago. It is fascinating that it took so long already.

There was no Chrome browser 10 years ago.

It does not matter which browser. All of them please.

Even IE and Edge sarcastic voice

I'm most excited about integration testing on sites with http/2 deployed.

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