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https://github.com/chazkii/chromewhip

Scriptable Google Chrome™ as a HTTP service + asyncio driver
https://github.com/chazkii/chromewhip

asyncio-driver chrome-process devtools-protocol google-chrome

Last synced: 2 months ago
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Scriptable Google Chrome™ as a HTTP service + asyncio driver

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README 

        
# Chromewhip - Google Chrome™ as a web service



[![Build Status](https://travis-ci.org/chuckus/chromewhip.svg?branch=master)](https://travis-ci.org/chuckus/chromewhip)

[![Docker Hub Status](https://img.shields.io/docker/build/chuckus/chromewhip.svg)](https://img.shields.io/docker/build/chuckus/chromewhip.svg)

[![PyPi version](https://img.shields.io/pypi/v/chromewhip.svg)](https://img.shields.io/pypi/v/chromewhip.svg)



### Chrome browser as an HTTP service with an splash compatible HTTP API



Chromewhip is an easily deployable service that runs headless Chrome process 

wrapped with an HTTP API. Inspired by the [`splash`](https://github.com/scrapinghub/splash) 

project, we aim to provide a drop-in replacement for the `splash` service by adhering to their documented API.



It is currently in early **alpha** and still being heavily developed. Please use the issue tracker 

to track the progress towards **beta**. For now, the required milestone can be summarised as 

**implementing the entire Splash API**.



## How to use as a service



One can simply deploy as a Docker container and use the API that is served on port `8080`.



```

docker run --init -it --rm --shm-size=1024m -p=127.0.0.1:8080:8080 --cap-add=SYS_ADMIN \

  chuckus/chromewhip

```



Refer to the HTTP API reference at the bottom of the README for what features are available.



## How to use the low-level driver



As part of the Chromewhip service, a Python 3.6 asyncio compatible driver for Chrome devtools protocol was 

developed and can be leveraged without having to run the HTTP server. The advantages of 

our devtools driver are:



* Typed Python bindings for devtools protocol through templated generation - get autocomplete with your code editor.

* Can bind events to concurrent commands, which is required for providing a robust HTTP service.



### Prerequisites



Before executing the code below, please have the following:



* Google Chrome Canary running with flag `--remote-debugging-port=9222`



### Example driver code



```python

import asyncio

import logging



from chromewhip import Chrome

from chromewhip.protocol import browser, page, dom



# see logging from chromewhip

logging.basicConfig(level=logging.DEBUG)



HOST = '127.0.0.1'

PORT = 9222



loop = asyncio.get_event_loop()

c = Chrome(host=HOST, port=PORT)



loop.run_until_complete(c.connect())



    

# use the startup tab or create a new one

tab = c.tabs[0]

tab = loop.run_until_complete(c.create_tab())



loop.run_until_complete(tab.enable_page_events())



def sync_cmd(*args, **kwargs):

    return loop.run_until_complete(tab.send_command(*args, **kwargs))

    

# send_command will return once the frameStoppedLoading event is received THAT matches

# the frameId that it is in the returned command payload.

result = sync_cmd(page.Page.navigate(url='http://nzherald.co.nz'), 

                  await_on_event_type=page.FrameStoppedLoadingEvent)



# send_command always returns a dict with keys `ack` and `event`

# `ack` contains the payload on response of a command

# `event` contains the payload of the awaited event if `await_on_event_type` is provided

ack = result['ack']['result']

event = result['event']

assert ack['frameId'] == event.frameId



sync_cmd(page.Page.setDeviceMetricsOverride(width=800,

                                            height=600,

                                            deviceScaleFactor=0.0,

                                            mobile=False))



result = sync_cmd(dom.DOM.getDocument())



dom_obj = result['ack']['result']['root']



# Python types are determined by the `types` fields in the JSON reference for the

# devtools protocol, and `send_command` will convert if possible.

assert isinstance(dom_obj, dom.Node)



print(dom_obj.nodeId)

print(dom_obj.nodeName)



# close the tab

loop.run_until_complete(c.close_tab(tab))



# or close the browser via Devtools API

tab = c.tabs[0]

sync_cmd(browser.Browser.close())

```



## Implemented HTTP API



### /render.html



Query params:



* url : string : required

  * The url to render (required)



* js : string : optional

  Javascript profile name.

  

* js_source : string : optional

   * JavaScript code to be executed in page context



* viewport : string : optional

  * View width and height (in pixels) of the browser viewport to render the web

    page. Format is "x", e.g. 800x600.  Default value is 1024x768.



    'viewport' parameter is more important for PNG and JPEG rendering; it is supported for

    all rendering endpoints because javascript code execution can depend on

    viewport size. 

 

### /render.png



Query params (including render.html):



* render_all : int : optional

  * Possible values are `1` and `0`.  When `render_all=1`, extend the

    viewport to include the whole webpage (possibly very tall) before rendering.

   

### Why not just use Selenium?

* chromewhip uses the devtools protocol instead of the json wire protocol, where the devtools protocol has 

greater flexibility, especially when it comes to subscribing to granular events from the browser.



## Bug reports and requests

Please simply file one using the Github tracker



## Contributing

Please :)



### How to regenerate the Python protocol files



In `scripts`, you can run `regenerate_protocol.sh`, which downloads HEAD of offical devtools specs, regenerates, 

runs some sanity tests and creates a commit with the message of official devtools specs HEAD.



From time to time, it will fail, due to desynchronization of the `chromewhip` patch with the json specs, or 

mistakes in the protocol.



Under `data`, there are `*_patch` files, which follow the [RFC 6902 JSON Patch notation](https://tools.ietf.org/html/rfc6902). 

You will see that there are some checks to see whether particular items in arrays exist before patching. If you get 

a `jsonpatch.JsonPatchTestFailed` exception, it's likely to desynchronization, so check the official spec and adjust 

the patch json file.



## Implementation



Developed to run on Python 3.6, it leverages both `aiohttp` and `asyncio` for the implementation of the 

asynchronous HTTP server that wraps `chrome`.