changedetection.io/changedetectionio/content_fetcher.py

from abc import ABC, abstractmethod
import chardet
import os
import requests
import time
import urllib3.exceptions
import sys


class EmptyReply(Exception):
    def __init__(self, status_code, url):
        # Set this so we can use it in other parts of the app
        self.status_code = status_code
        self.url = url
        return

    pass


class Fetcher():
    error = None
    status_code = None
    content = None
    headers = None
    # Will be needed in the future by the VisualSelector, always get this where possible.
    screenshot = False
    fetcher_description = "No description"
    system_http_proxy = os.getenv('HTTP_PROXY')
    system_https_proxy = os.getenv('HTTPS_PROXY')

    @abstractmethod
    def get_error(self):
        return self.error

    @abstractmethod
    def run(self,
            url,
            timeout,
            request_headers,
            request_body,
            request_method,
            ignore_status_codes=False):
        # Should set self.error, self.status_code and self.content
        pass

    @abstractmethod
    def quit(self):
        return

    @abstractmethod
    def get_last_status_code(self):
        return self.status_code

    @abstractmethod
    # Return true/false if this checker is ready to run, in the case it needs todo some special config check etc
    def is_ready(self):
        return True


#   Maybe for the future, each fetcher provides its own diff output, could be used for text, image
#   the current one would return javascript output (as we use JS to generate the diff)
#
def available_fetchers():
    # See the if statement at the bottom of this file for how we switch between playwright and webdriver
    import inspect
    p = []
    for name, obj in inspect.getmembers(sys.modules[__name__], inspect.isclass):
        if inspect.isclass(obj):
            # @todo html_ is maybe better as fetcher_ or something
            # In this case, make sure to edit the default one in store.py and fetch_site_status.py
            if name.startswith('html_'):
                t = tuple([name, obj.fetcher_description])
                p.append(t)

    return p


class base_html_playwright(Fetcher):
    fetcher_description = "Playwright {}/Javascript".format(
        os.getenv("PLAYWRIGHT_BROWSER_TYPE", 'chromium').capitalize()
    )
    if os.getenv("PLAYWRIGHT_DRIVER_URL"):
        fetcher_description += " via '{}'".format(os.getenv("PLAYWRIGHT_DRIVER_URL"))

    browser_type = ''
    command_executor = ''

    # Configs for Proxy setup
    # In the ENV vars, is prefixed with "playwright_proxy_", so it is for example "playwright_proxy_server"
    playwright_proxy_settings_mappings = ['bypass', 'server', 'username', 'password']

    proxy = None

    def __init__(self, proxy_override=None):

        # .strip('"') is going to save someone a lot of time when they accidently wrap the env value
        self.browser_type = os.getenv("PLAYWRIGHT_BROWSER_TYPE", 'chromium').strip('"')
        self.command_executor = os.getenv(
            "PLAYWRIGHT_DRIVER_URL",
            'ws://playwright-chrome:3000/playwright'
        ).strip('"')

        # If any proxy settings are enabled, then we should setup the proxy object
        proxy_args = {}
        for k in self.playwright_proxy_settings_mappings:
            v = os.getenv('playwright_proxy_' + k, False)
            if v:
                proxy_args[k] = v.strip('"')

        if proxy_args:
            self.proxy = proxy_args

        # allow per-watch proxy selection override
        if proxy_override:
            self.proxy = {'server': proxy_override}

    def run(self,
            url,
            timeout,
            request_headers,
            request_body,
            request_method,
            ignore_status_codes=False):

        from playwright.sync_api import sync_playwright
        import playwright._impl._api_types
        from playwright._impl._api_types import Error, TimeoutError

        with sync_playwright() as p:
            browser_type = getattr(p, self.browser_type)

            # Seemed to cause a connection Exception even tho I can see it connect
            # self.browser = browser_type.connect(self.command_executor, timeout=timeout*1000)
            browser = browser_type.connect_over_cdp(self.command_executor, timeout=timeout * 1000)

            # Set user agent to prevent Cloudflare from blocking the browser
            # Use the default one configured in the App.py model that's passed from fetch_site_status.py
            context = browser.new_context(
                user_agent=request_headers['User-Agent'] if request_headers.get('User-Agent') else 'Mozilla/5.0',
                proxy=self.proxy
            )
            page = context.new_page()
            page.set_viewport_size({"width": 1280, "height": 1024})
            try:
                response = page.goto(url, timeout=timeout * 1000, wait_until='commit')
                # Wait_until = commit
                # - `'commit'` - consider operation to be finished when network response is received and the document started loading.
                # Better to not use any smarts from Playwright and just wait an arbitrary number of seconds
                # This seemed to solve nearly all 'TimeoutErrors'
                extra_wait = int(os.getenv("WEBDRIVER_DELAY_BEFORE_CONTENT_READY", 5))
                page.wait_for_timeout(extra_wait * 1000)
            except playwright._impl._api_types.TimeoutError as e:
                raise EmptyReply(url=url, status_code=None)

            if response is None:
                raise EmptyReply(url=url, status_code=None)

            self.status_code = response.status
            self.content = page.content()
            self.headers = response.all_headers()

            # Some bug where it gives the wrong screenshot size, but making a request with the clip set first seems to solve it
            # JPEG is better here because the screenshots can be very very large
            page.screenshot(type='jpeg', clip={'x': 1.0, 'y': 1.0, 'width': 1280, 'height': 1024})
            self.screenshot = page.screenshot(type='jpeg', full_page=True, quality=90)
            context.close()
            browser.close()


class base_html_webdriver(Fetcher):
    if os.getenv("WEBDRIVER_URL"):
        fetcher_description = "WebDriver Chrome/Javascript via '{}'".format(os.getenv("WEBDRIVER_URL"))
    else:
        fetcher_description = "WebDriver Chrome/Javascript"

    command_executor = ''

    # Configs for Proxy setup
    # In the ENV vars, is prefixed with "webdriver_", so it is for example "webdriver_sslProxy"
    selenium_proxy_settings_mappings = ['proxyType', 'ftpProxy', 'httpProxy', 'noProxy',
                                        'proxyAutoconfigUrl', 'sslProxy', 'autodetect',
                                        'socksProxy', 'socksVersion', 'socksUsername', 'socksPassword']
    proxy = None

    def __init__(self, proxy_override=None):
        from selenium.webdriver.common.proxy import Proxy as SeleniumProxy

        # .strip('"') is going to save someone a lot of time when they accidently wrap the env value
        self.command_executor = os.getenv("WEBDRIVER_URL", 'http://browser-chrome:4444/wd/hub').strip('"')

        # If any proxy settings are enabled, then we should setup the proxy object
        proxy_args = {}
        for k in self.selenium_proxy_settings_mappings:
            v = os.getenv('webdriver_' + k, False)
            if v:
                proxy_args[k] = v.strip('"')

        # Map back standard HTTP_ and HTTPS_PROXY to webDriver httpProxy/sslProxy
        if not proxy_args.get('webdriver_httpProxy') and self.system_http_proxy:
            proxy_args['httpProxy'] = self.system_http_proxy
        if not proxy_args.get('webdriver_sslProxy') and self.system_https_proxy:
            proxy_args['httpsProxy'] = self.system_https_proxy

        # Allows override the proxy on a per-request basis
        if proxy_override is not None:
            proxy_args['httpProxy'] = proxy_override

        if proxy_args:
            self.proxy = SeleniumProxy(raw=proxy_args)

    def run(self,
            url,
            timeout,
            request_headers,
            request_body,
            request_method,
            ignore_status_codes=False):

        from selenium import webdriver
        from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
        from selenium.common.exceptions import WebDriverException
        # request_body, request_method unused for now, until some magic in the future happens.

        # check env for WEBDRIVER_URL
        self.driver = webdriver.Remote(
            command_executor=self.command_executor,
            desired_capabilities=DesiredCapabilities.CHROME,
            proxy=self.proxy)

        try:
            self.driver.get(url)
        except WebDriverException as e:
            # Be sure we close the session window
            self.quit()
            raise

        # @todo - how to check this? is it possible?
        self.status_code = 200
        # @todo somehow we should try to get this working for WebDriver
        # raise EmptyReply(url=url, status_code=r.status_code)

        # @todo - dom wait loaded?
        time.sleep(int(os.getenv("WEBDRIVER_DELAY_BEFORE_CONTENT_READY", 5)))
        self.content = self.driver.page_source
        self.headers = {}
        self.screenshot = self.driver.get_screenshot_as_png()
        self.quit()

    # Does the connection to the webdriver work? run a test connection.
    def is_ready(self):
        from selenium import webdriver
        from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
        from selenium.common.exceptions import WebDriverException

        self.driver = webdriver.Remote(
            command_executor=self.command_executor,
            desired_capabilities=DesiredCapabilities.CHROME)

        # driver.quit() seems to cause better exceptions
        self.quit()
        return True

    def quit(self):
        if self.driver:
            try:
                self.driver.quit()
            except Exception as e:
                print("Exception in chrome shutdown/quit" + str(e))


# "html_requests" is listed as the default fetcher in store.py!
class html_requests(Fetcher):
    fetcher_description = "Basic fast Plaintext/HTTP Client"

    def __init__(self, proxy_override=None):
        self.proxy_override = proxy_override

    def run(self,
            url,
            timeout,
            request_headers,
            request_body,
            request_method,
            ignore_status_codes=False):

        proxies={}

        # Allows override the proxy on a per-request basis
        if self.proxy_override:
            proxies = {'http': self.proxy_override, 'https': self.proxy_override, 'ftp': self.proxy_override}
        else:
            if self.system_http_proxy:
                proxies['http'] = self.system_http_proxy
            if self.system_https_proxy:
                proxies['https'] = self.system_https_proxy

        r = requests.request(method=request_method,
                             data=request_body,
                             url=url,
                             headers=request_headers,
                             timeout=timeout,
                             proxies=proxies,
                             verify=False)

        # If the response did not tell us what encoding format to expect, Then use chardet to override what `requests` thinks.
        # For example - some sites don't tell us it's utf-8, but return utf-8 content
        # This seems to not occur when using webdriver/selenium, it seems to detect the text encoding more reliably.
        # https://github.com/psf/requests/issues/1604 good info about requests encoding detection
        if not r.headers.get('content-type') or not 'charset=' in r.headers.get('content-type'):
            encoding = chardet.detect(r.content)['encoding']
            if encoding:
                r.encoding = encoding

        # @todo test this
        # @todo maybe you really want to test zero-byte return pages?
        if (not ignore_status_codes and not r) or not r.content or not len(r.content):
            raise EmptyReply(url=url, status_code=r.status_code)

        self.status_code = r.status_code
        self.content = r.text
        self.headers = r.headers


# Decide which is the 'real' HTML webdriver, this is more a system wide config
# rather than site-specific.
use_playwright_as_chrome_fetcher = os.getenv('PLAYWRIGHT_DRIVER_URL', False)
if use_playwright_as_chrome_fetcher:
    html_webdriver = base_html_playwright
else:
    html_webdriver = base_html_webdriver