Cannot Overwrite Headers for Python's `Route.continue_`

Hi all! I first want to say that I love Playwright – it is incredibly seamless and lightning fast. From my experience so far, it has a simple yet powerful API, and is a lot less clunky than Selenium.

My team is trying to use it to render PDFs, and we need to set the Origin header to avoid CORS issues. I have found an issue that has plagued me on Ubuntu and MacOS Big Sur, with Python 3.9.5 and Playwright (Python) 1.12.1.

Using a modified Spec example, here is our issue:

from playwright.sync_api import sync_playwright

def handle(route, request):
    headers = {
        **request.headers,
        'foo': 'bar', # set 'foo' header
        'origin': 'literally_anywhere'
    }
    route.continue_(headers=headers)

with sync_playwright() as pw:
    browser = pw.chromium.launch()
    page = browser.new_page()
    page.route("**/*", handle)
    page.on('request', lambda request: print(f'====request headers: ({request.url})====\n{request.headers}\n'))
    browser.close()

'foo' is being set erratically – only on two of the page requests that are logged. 'origin' is never set. In addition, the spec example cites being able to set 'origin': None, but for me it throws

playwright._impl._api_types.Error: headers[4].value: expected string, got object

Installation procedure was as follows:

# (in a python3 venv virtual environment)
pip install playwright
PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD=1 python -m playwright install
playwright install chromium

Thank you in advance for any help! Please let me know if this is just a configuration issue.

[mxschmitt]

I digged into it. The reason is at least in the reproducible, that it’s based on redirects which is currently an upstream limitation. When you are using https://www.google.com it works. Their redirect chain is: http://google.com -> https://google.com -> https://www.google.com.

PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD=1 python -m playwright install this will like result in doing nothing. You are saying basically, hey install browsers but the skip env var is set, so its not installing anything at all.

[mxschmitt]

Closed for now, lets reopen if the problem is still persistent.